BD7F205EFJ-C (新产品)

Datasheet

Isolated DC/DC Converter IC

Isolated Type Fly-back Converter IC

with Integrated Switching MOSFET

for Automotive

BD7F205EFJ-C

General Description

Key Specifications

◼ Input Voltage Range:

VIN Pin

BD7F205EFJ-C is an opto-coupler-less isolated flyback

converter. Feedback circuit by optocouplers or the

auxiliary winding of transformers becomes unnecessary,

contributing to reduction of set parts. Furthermore, the

adoption of original adapted ON-time control technology

enables fast load response. In addition, the various

protection function realizes the designs of isolated power

supply application for high reliability.

3.4 V to 42.0 V

60 V (Max)

363 kHz (Typ)

± 2.8 % (Typ)

0 μA (Typ)

SW Pin

◼ Switching Frequency:

◼ Reference Voltage Precision:

◼ Shutdown Current:

◼ Operating Ambient Temperature Range

-40 °C to +125 °C

Features

Package

HTSOP-J8

W (Typ) x D (Typ) x H (Max)

◼ AEC-Q100 Qualified ^{(Note 1)}

4.9 mm x 6.0 mm x 1.0 mm

◼ No Need for Optocoupler and Third Winding of

Transformer

◼ Set Output Voltage with Two External Resistors and

Ratio of Transformer Turns

◼ Adopt of Original Adapted ON-Time Control Technology

Fast Load Response

◼ High Efficiency at Light Load Mode (PFM Operation)

◼ Shutdown Function / Enable Control

◼ Built-in 60 V Switching MOSFET

◼ Frequency Spectrum Spread

◼ Soft Start Function

◼ Load Compensation Function

◼ Various Protection Function

Input Low Voltage Lockout (UVLO)

Over Current Protection (OCP)

Thermal Shutdown (TSD)

Applications

◼

Automotive Isolated Power Supplies

(E-Comp, Inverter etc)

◼

Industrial Isolated Power Supplies

REF Pin Open Protection (REFOPEN)

Short Circuit Protection (SCP)

Battery Short Protection (BSP)

◼ HTSOP-J8 Package

(Note 1) Grade 1

Typical Application Circuit

VF

VOUT+

VIN

NS

NP

SDX/EN

VOUT-

SW

FB

REF GND

L_COMP

RFB

RREF

〇Product structure : Silicon integrated circuit 〇This product has no designed protection against radioactive rays.

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Contents

General Description........................................................................................................................................................................1

Features..........................................................................................................................................................................................1

Key Specifications ..........................................................................................................................................................................1

Package..........................................................................................................................................................................................1

Applications ....................................................................................................................................................................................1

Typical Application Circuit...............................................................................................................................................................1

Contents .........................................................................................................................................................................................2

Pin Configuration ............................................................................................................................................................................3

Pin Descriptions..............................................................................................................................................................................3

Block Diagram ................................................................................................................................................................................3

Description of Blocks ......................................................................................................................................................................4

1

2

3

4

5

6

7

8

INTERNAL REGULATOR.................................................................................................................................................4

Input Low Voltage Lock Out (UVLO).................................................................................................................................4

Thermal Shutdown (TSD).................................................................................................................................................5

SW VOLTAGE DETECTION.............................................................................................................................................5

SOFT START....................................................................................................................................................................5

PWM COMPARATOR.......................................................................................................................................................5

ADAPTIVE ON TIME CONTROLLER ..............................................................................................................................5

Maximum Frequency Limit Function (MAX FREQ)...........................................................................................................5

DRIVER............................................................................................................................................................................5

Nch MOSFET...................................................................................................................................................................5

LOAD COMPENSATION..................................................................................................................................................6

Frequency Spectrum Spread (SPECTRUM SPREAD).....................................................................................................6

Over Current Protection (OCP), Battery Short Protection (BSP) ......................................................................................6

Short Circuit Protection (SCP), REF Pin Open Protection (REFOPEN) ...........................................................................7

9

10

11

12

13

14

Absolute Maximum Ratings ............................................................................................................................................................8

Thermal Resistance........................................................................................................................................................................8

Recommended Operating Conditions.............................................................................................................................................8

Electrical Characteristics.................................................................................................................................................................9

Typical Performance Curves.........................................................................................................................................................10

Application Examples ...................................................................................................................................................................18

1

2

3

4

5

6

7

8

Output Voltage................................................................................................................................................................18

Transformer....................................................................................................................................................................20

Output Capacitor ............................................................................................................................................................22

Input Capacitor...............................................................................................................................................................22

Secondary Output Diode ................................................................................................................................................23

Output Resistor and Output Zener Diode (Minimum Load Current)................................................................................23

Snubber Circuit...............................................................................................................................................................24

Setting of SDX/EN Pin Resistor......................................................................................................................................24

The Output Voltage Compensation Function by L_COMP Pin Resistor .........................................................................25

The Influence on Frequency and Output Voltage for Each Load ....................................................................................26

9

10

I/O Equivalence Circuits................................................................................................................................................................27

Operational Notes.........................................................................................................................................................................28

Ordering Information.....................................................................................................................................................................30

Marking Diagram ..........................................................................................................................................................................30

Physical Dimension and Packing Information...............................................................................................................................31

Revision History............................................................................................................................................................................32

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Pin Configuration

Pin Descriptions

Pin No.

Pin Name

GND

Function

1

2

3

4

5

6

7

8

-

GND pin

SDX/EN

L_COMP

REF

Shutdown/Enable control pin

Setting pin of load current compensation value pin

Output voltage setting pin

FB

Output voltage setting pin

No Connect ^{(Note 1)}

N.C.

SW

Switching output pin

VIN

Power supply input pin

EXP-PAD

Connect EXP-PAD to GND on PCB ^{(Note 2)}

(Note 1) The N.C pin does not have internal connection. Open the pin when mounting board.

(Note 2) The EXP-Pad pin is connected to GND on the mounting board.

Block Diagram

VIN

FB

SW

SPECTRUM

SPREAD

SW

VOLTAGE

DETECTION

SCP

INTERNAL

REGULATOR

REFOPEN

PWM

COMPARATOR

Nch

MOSFET

ADAPTIVE

ON-TIME

V_INTREF

DRIVER

CONTROLLER

SOFT

START

UVLO

TSD

SDX/EN

OCP

BSP

MAXFREQ

LOAD

COMPENSATION

REF

L_COMP

GND

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Description of Blocks

1

INTERNAL REGULATOR

This is regulator block for internal circuits.

This block shuts itself down at the shutdown status of SDX/EN pin voltage V_SDXor less.

When SDX/EN pin voltage rises V_SDXor above, IC consumption current increases.

When SDX/EN pin voltage is V_EN1or above, IC enters the enable status and starts switching operation.

The soft start function operates for t_SSperiod from switching start, and the output voltage rises slowly.

When SDX/EN pin voltage falls V_EN2or below, IC enters the disables status and the switching operation is stopped.

VIN

pin voltage

VEN1

VEN2

VSDX

SDX/EN

pin voltage

tss

Output

voltage

Switching

ON

Figure 1. Startup and Stop Timing Chart

2

Input Low Voltage Lock Out (UVLO)

This is the protection function for the low input voltage of the VIN pin.

When VIN pin voltage falls V_UVLO1or below, IC detects UVLO and stops switching operation.

When VIN pin voltage rises V_UVLO2or above, IC starts switching operation and a soft start function operates during the

period of t_SS

.

VUVLO2

VUVLO1

VIN

pin voltage

0 V

tss

Output

voltage

ON

Switching

ON

Figure 2. VIN UVLO Timing Chart

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Description of Blocks – continued

3

4

5

Thermal Shutdown (TSD)

This block is the thermal shutdown circuit that prevents heat damage to the IC. When IC junction temperature rises

more than 175 °C (Typ), IC stops switching operation. After that When IC junction temperature falls IC restarts. The

temperature hysteresis is 25 °C (Typ). The TSD function aims to protect itself. So IC junction temperature should be

designed less than Tjmax = 150 °C. For that, it should not use as over temperature protection function of application.

SW VOLTAGE DETECTION

This block detects the flyback voltage generated in the SW pin. In turn-off of the transformer, this block converts

current to flow from the FB pin into voltage by the resistance of the REF pin and the flyback voltage is detected by this

REF pin voltage.

The IC controls REF pin voltage to be equivalent to V_INTREF

.

SOFT START

When IC turns to enable status that SDX/EN pin voltage is V_EN1or above, the comparison voltage of the PWM

COMPARATOR block increases gradually from 0 V to V_INTREF. PWM comparator voltage is constantly V_INTREFafter

soft start time passed.

This operation prevents from the output voltage overshooting. The soft start time is fixed to t_SSin the IC.

And SCP protection is invalid for t_MASKSCPperiod from start-up.

6

7

PWM COMPARATOR

This block compares REF pin voltage equivalent to feedback voltage of the output voltage with soft start voltage or

reference voltage V_INTREF. This comparator output decides the ON timing.

Since it does not have error amplifier and constitutes a feedback loop by the comparator, IC enables fast control to

load response during PWM operation.

ADAPTIVE ON TIME CONTROLLER

This block is ON time control block which uses original adapted ON-time control technology.

Stable load current:

Fluctuating load current:

IC operates in PWM operation by constant ON time control.

IC operates in the constant ON time control and fluctuate the switching

frequency. It results from fast response.

Light load:

The switching frequency decreases and realizes a high efficiency by PFM

operation during discontinuous mode.

When the load current fluctuates, IC operates f_{SW_MAX}or below. IC raises the primary average current by shortening

the off time. It results from increasing the secondary current and secondary output voltage is quickly stable.

Output current

Output voltage

Primary coil current

SW pin voltage

High

Frequency

Stabilize gradually

Stable operation

Switching Frequency

Stable operation at light load

Figure 3. Load Response Timing Chart

8

9

Maximum Frequency Limit Function (MAX FREQ)

This function limits the maximum frequency. The switching frequency is instantly high at ON width control in start-up

or load response. It may influence to EMI. For that, IC limits max frequency less than f_{SW_MAX}

.

DRIVER

This is the block which drives Nch MOSFET for switching.

10 Nch MOSFET

This is Nch MOSFET for switching.

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Description of Blocks – continued

11 LOAD COMPENSATION

This block compensates the decrease of output voltage caused by the change of V_Fcharacteristic in the secondary

output diode which is proportional to load current. It monitors the current flown to the switching MOSFET and a part of

the current flows to the REF pin. The quantity of compensation determines by the external resistor and capacitor at

the L_COMP pin and K_{L_COMP}which is coefficient for SW current. For that, as the current flown from the FB pin to the

external resistor of the REF pin decreases, the output voltage decrease is compensated.

12 Frequency Spectrum Spread (SPECTRUM SPREAD)

This is the function to spread switching frequency.

The frequency spreading in the range of ±5 % contributes to low EMI.

13 Over Current Protection (OCP), Battery Short Protection (BSP)

This function is over current protection of the MOSFET.

13.1 Over Current Protection (OCP)

When the switching MOSFET is on, as the primary transformer peak current becomes I_LIMITor more, IC detects

the over current and the switching MOSFET is turned off. Because IC detects OCP per switching cycles, ON duty

is limited and the output voltage drops. In addition, to prevent miss detection by turn ON surge, the detection of

OCP is invalid for t_{ON_MIN}after the switching MOSFET is turned on.

After IC detects OCP, switching MOSFET is turn off after a delay time. When VIN voltage is increased, I_LIMITis

higher by the rise of current slope. ΔI_LIMITdepends on L_Pvalue of transformer.

∆퐼_{퐿ꢀ푀ꢀ푇}= 푉퐼푁 × 푡_{퐷퐸퐿퐴푌}/ ꢁ_푃

푡_{퐷퐸퐿퐴푌}

ꢁ_푃

:

OCP detection delay time

Primary inductance

푡_{퐷퐸퐿퐴푌}is always 0.2 µs or less.

Output voltage

I_LIMIT

Primary coil current

SW pin voltage

t_{ON_MIN}

OCP

Normal

IC status

Figure 4. OCP Timing Chart

13.2 Battery Short Protection (BSP)

In the case of increasing peak current by CCM (Continuous Conduction Mode) operation such as the short of the

transformer winding or output short of secondary, large current over I_LIMITis flown to the switching MOSFET. To

prevent this phenomenon, IC is built-in BSP function. When SW pin current becomes I_BSPor more at the

switching MOSFET ON, the IC detects BSP. By this function, the switching operation is stopped in the period of

t_BSP. After it passes t_BSP, IC recovers switching operation without soft-start function. When BSP state continues,

IC stops switching operation by SCP protection because output voltage is low. BSP is affected by the delay time

(t_DELAY) the same as OCP, and I_BSPincreases according to VIN voltage. Also, when primary transformer is short,

the function is operated.

Battery short is happened

I_BSP

Primary Coil

current

SW pin voltage

ON

t_BSP

Switching

t_BSP

Output voltage

Figure 5. BSP Timing Chart

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Description of Blocks – continued

14 Short Circuit Protection (SCP), REF Pin Open Protection (REFOPEN)

This is the block of the short protection and the open protection of the REF pin.

14.1 Short Circuit Protection (SCP)

As IC converts the primary flyback voltage to REF pin voltage, IC detects secondary output status. When

secondary output voltage drops, REF pin voltage also drops. When REF pin voltage is V_SCPor below, IC detects

SCP. When the detection continues for t_MASK, the switching operation is stopped. After the time of t_RESTARTpasses

from the stop, IC restarts with soft start function. To prevent SCP miss detection, the detection of SCP is invalid

for t_MASKSCPat start-up. When REF voltage is V_SCPor below for t_MASKSCPfrom start-up, IC stops switching for

t_RESTART

.

t_SS

tMASK

Output voltage

SW pin voltage

V_SCP

REF pin voltage

Switching

ON

t_RESTART

SCP status

ON

Figure 6. SCP Timing Chart

14.2 REF Pin Open Protection (REFOPEN)

The REF pin detects the secondary output voltage status from the primary flyback voltage. When the REF pin is

open, output status is not detected, and switching MOSFET may occur malfunction. Therefore, when the REF

pin voltage is V_REFOPor above, the IC detects REFOPEN protection. When the detection continues for t_MASK, the

switching operation is stopped. After the time of t_RESTARTfrom the stop, IC restarts with soft start function.

When auto recovery, IC operates for t_MASKfrom start-up. When REF pin voltage is V_REFOPor above for t_MASK, IC

stops switching for t_RESTART

.

t_SS

Output voltage

SW pin voltage

V_REFOP

REF pin voltage

t_MASK

t_RESTART

ON

Switching

ON

REFOPEN

status

Figure 7. REFOPEN Protection Timing Chart

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Absolute Maximum Ratings （Ta = 25 °C）

Parameter

VIN Pin Voltage

Symbol

Rating

Unit

V_IN

V_SW

-0.3 to +45

-0.3 to +62

-0.3 to +45

-0.3 to +7

150

V

SW Pin Voltage

SDX/EN Pin Voltage

FB Pin Voltage

V_SDX/EN

V_FB

V

REF Pin Voltage

V_REF

V

L_COMP Pin Voltage

Maximum Junction Temperature

Storage Temperature Range

V_{L_COMP}

Tjmax

Tstg

V

°C

-55 to +150

°C

Caution 1: Operating the IC over the absolute maximum ratings may damage the IC. The damage can either be a short circuit between pins or an open circuit

between pins and the internal circuitry. Therefore, it is important to consider circuit protection measures, such as adding a fuse, in case the IC is

operated over the absolute maximum ratings.

Caution 2: Should by any chance the maximum junction temperature rating be exceeded the rise in temperature of the chip may result in deterioration of the

properties of the chip. In case of exceeding this absolute maximum rating, design a PCB with thermal resistance taken into consideration by

increasing board size and copper area so as not to exceed the maximum junction temperature rating.

Thermal Resistance^{(Note 1)}

Thermal Resistance (Typ)

Parameter

Symbol

Unit

1s ^{(Note 3)}

2s2p ^{(Note 4)}

HTSOP-J8

Junction to Ambient

Junction to Top Characterization Parameter ^{(Note 2)}

θ_JA

206.4

21

45.2

13

°C/W

Ψ_JT

(Note 1) Based on JESD51-2 A (Still-Air).

(Note 2) The thermal characterization parameter to report the difference between junction temperature and the temperature at the top center of the outside

surface of the component package.

(Note 3) Using a PCB board based on JESD51-3.

(Note 4) Using a PCB board based on JESD51-5, 7.

Layer Number of

Measurement Board

Material

Board Size

Single

FR-4

114.3 mm x 76.2 mm x 1.57 mmt

Top

Copper Pattern

Thickness

70 μm

Footprints and Traces

Layer Number of

Measurement Board

Thermal Via ^{(Note 5)}

Material

Board Size

114.3 mm x 76.2 mm x 1.6 mmt

2 Internal Layers

Pitch

Diameter

4 Layers

FR-4

1.20 mm

Φ0.30 mm

Top

Copper Pattern

Bottom

Thickness

70 μm

Copper Pattern

Thickness

Copper Pattern

Thickness

Footprints and Traces

74.2 mm x 74.2 mm

35 μm

74.2 mm x 74.2 mm

70 μm

(Note 5) This thermal via connect with the copper pattern of layers 1,2, and 4. The placement and dimensions obey a land pattern.

Recommended Operating Conditions

Parameter

Symbol

Min

Typ

Max

Unit

Conditions

Operation Power Supply Voltage Range

Operation Voltage Range

Operation Temperature

REF Pin Resistor

V_IN

V_SW

3.4

-

12.0

42.0

60

V

VIN pin voltage

SW pin Voltage

-

Topr

-40

-

2.7

-

+125

-

°C

R_REF

V_{L_COMP}

C_VIN

kΩ External resistor value ^{(Note 6)}

L_COMP Voltage Range

-

1.00

V

L_COMP pin voltage

VIN-GND Capacitor

10

-

µF

(Note 6) Set the REF resistor value of 2.7 kΩ (Typ). Choose the resistance accuracy for an output voltage accuracy.

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Electrical Characteristics (Unless otherwise Tj = -40 °C to +150 °C, V_IN= 12 V, V_SDX/EN= 2.5 V)

Parameter

Symbol

Min

Typ

Max

Unit

Conditions

Power Supply Block

SDX/EN = 0.3 V

Tj ≤ 125 °C

Current at Shutdown

I_ST

-

0

10

μA

REF = 0.6 V

Operating Current at No Switching

UVLO Detection Voltage 1

UVLO Detection Voltage 2

UVLO Voltage Hysteresis

I_CC

0.43

3.00

3.20

0.12

1.00

3.20

3.40

0.20

1.70

3.40

3.60

0.28

mA

V

V_UVLO1

At the VIN pin falling

At the VIN pin rising

V_UVLO2

V

V_{UVLO_HYS}

V

Shutdown and Enable Control Block

Shutdown Voltage at the SDX/EN Pin

Enable Voltage 1

V_SDX

V_EN1

-

0.3

2.10

2.00

0.26

2.00

3750

V

1.90

1.60

0.14

0.50

1250

2.00

1.80

0.20

1.00

2500

At the SDX/EN pin rising

At the SDX/EN pin falling

Enable Voltage 2

V_EN2

V

Enable Voltage Hysteresis

SDX/EN Pin Current

V_{EN_HYS}

I_SDX/EN

R_SDX/EN

V

μA

kΩ

SDX/EN = 2.5 V

SDX/EN Pin Pull-down Resistance

Reference Voltage Block

Reference Voltage

REF Pin Current

V_INTREF

I_REF

0.525

140

0.540

200

0.555

260

V

μA

R_REF= 2.7 kΩ

Switching Block

On Resistance

R_ON

I_LIMIT

I_BSP

-

0.18

3.80

4.94

0.36

4.56

6.61

Ω

A

SW-GND I_SW= 50 mA

Over Current Detection Current

BSP Detection Current

3.04

3.50

At PWM operation

(Duty = 40 %)

Averaging Switching Frequency

Maximum Switching Frequency

On Time

f_SW

f_{SW_MAX}

t_ON

300

-

363

-

430

498

kHz

μs

At PWM operation

(Duty = 40 %)

0.962

1.102

1.270

Minimum ON Time

Maximum OFF Time

t_{ON_MIN}

120

25

250

35

380

45

ns

μs

t_{OFF_MAX}

From switching start to V_INTREF

x 90 %

Soft Start Time

t_SS

6.0

10.0

14.0

ms

Protection Function Block

Short Protection Detection Voltage

REFOPEN Protection Detection Voltage

SCP/REFOPEN Detection Mask Time

SCP Mask Time at Start-up

V_SCP

V_REFOP

t_MASK

0.20

0.60

1.05

10.5

262

0.30

0.70

1.50

15.0

375

0.40

0.80

1.95

19.5

488

V

ms

µs

ms

t_MASKSCP

t_BSP

BSP Stop Time at Detection

Restart Time

t_RESTART

36.0

48.0

60.0

Load Compensation Block

KL_COMP (Compensation Coefficient of

REF Current for SW Current)

(Note 1)

K_{L_COMP}0.0480 0.0686 0.0892 %/MΩ

(Note 1) Load compensation current coefficient is the coefficient which compensates output voltage decrease for output current.

It sets by L_COMP pin resistor. It is tested at R_{L_COMP}= 10 kΩ.

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Typical Performance Curves

(Reference Data)

10

9

8

7

6

5

4

3

2

1

0

1.7

1.5

1.3

1.1

0.9

0.7

0.5

0.3

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 8. Current at Shutdown vs Temperature

Figure 9. Operating Current at No Switching vs Temperature

3.40

3.60

3.55

3.50

3.45

3.40

3.35

3.30

3.25

3.20

3.35

3.30

3.25

3.20

3.15

3.10

3.05

3.00

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 10. UVLO Detection Voltage1 vs Temperature

Figure 11. UVLO Detection Voltage2 vs Temperature

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Typical Performance Curves – continued

(Reference Data)

0.28

0.26

0.24

0.22

0.20

0.18

0.16

0.14

0.12

1.5

1.3

1.1

0.9

0.7

0.5

0.3

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 12. UVLO Voltage Hysteresis vs Temperature

Figure 13. Shutdown Voltage at the SDX/EN Pin vs

Temperature

2.10

2.00

1.95

1.90

1.85

1.80

1.75

1.70

1.65

1.60

2.05

2.00

1.95

1.90

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 14. Enable Voltage1 vs Temperature

Figure 15. Enable Voltage2 vs Temperature

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Typical Performance Curves – continued

(Reference Data)

0.26

0.24

0.22

0.20

0.18

0.16

0.14

2.00

1.80

1.60

1.40

1.20

1.00

0.80

0.60

0.40

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 16. Enable Voltage Hysteresis vs Temperature

Figure 17. SDX/EN Pin Current vs Temperature

3,750

0.555

0.550

0.545

0.540

0.535

0.530

0.525

3,250

2,750

2,250

1,750

1,250

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 18. SDX/EN Pin Pull-down Resistance vs Temperature

Figure 19. Reference Voltage vs Temperature

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Typical Performance Curves – continued

(Reference Data)

260

240

220

200

180

160

140

0.50

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0.00

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 20. REF Pin Current vs Temperature

Figure 21. On Resistance vs Temperature

4.6

6.9

6.4

5.9

5.4

4.9

4.4

3.9

3.4

4.4

4.2

4.0

3.8

3.6

3.4

3.2

3.0

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 22. Over Current Detection Current vs Temperature

Figure 23. BSP Detection Current vs Temperature

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Typical Performance Curves – continued

(Reference Data)

440

420

400

380

360

340

320

300

500

490

480

470

460

450

440

430

420

410

400

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 24. Averaging Switching Frequency vs Temperature

Figure 25. Maximum Switching Frequency vs Temperature

1.30

1.25

1.20

1.15

1.10

1.05

1.00

0.95

400

350

300

250

200

150

100

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 26. On Time vs Temperature

(Duty = 40 %, f_SW= 363 kHz)

Figure 27. Minimum ON Time vs Temperature

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Typical Performance Curves – continued

(Reference Data)

45

43

41

39

37

35

33

31

29

27

25

13.0

12.0

11.0

10.0

9.0

8.0

7.0

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 28. Maximum OFF Time vs Temperature

Figure 29. Soft Start Time vs Temperature

0.40

0.38

0.36

0.34

0.32

0.30

0.28

0.26

0.24

0.22

0.20

0.80

0.78

0.76

0.74

0.72

0.70

0.68

0.66

0.64

0.62

0.60

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 30. Short Protection Detection Voltage

vs Temperature

Figure 31. REFOPEN Protection Detection Voltage

vs Temperature

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Typical Performance Curves – continued

(Reference Data)

2.0

1.9

1.8

1.7

1.6

1.5

1.4

1.3

1.2

1.1

1.0

20

19

18

17

16

15

14

13

12

11

10

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 32. SCP/REFOPEN Detection Mask Time

vs Temperature

Figure 33. SCP Mask Time at Start-up vs Temperature

500

450

400

350

300

250

60.0

55.0

50.0

45.0

40.0

35.0

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 34. BSP Stop Time at Detection vs Temperature

Figure 35. Restart Time vs Temperature

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Typical Performance Curves – continued

(Reference Data)

0.100

0.090

0.080

0.070

0.060

0.050

0.040

-40 -20

0

20 40 60 80 100 120 140 160

Temperature [°C]

Figure 36. KL_COMP vs Temperature

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Application Examples

1

Output Voltage

When the internal switching MOSFET is off, SW pin voltage ”V_SW” is higher than VIN pin voltage. The secondary

output voltage is calculated by the primary flyback voltage, which is described by the difference between this SW pin

voltage and VIN pin voltage. The SW pin voltage at turn off is calculated by the following formula.

푁_푃

( )

× 푉_푂푈푇+ 푉_퐹

푉

푆푊

= 푉 +

[V]

ꢀꢂ

푁_푆

where:

푉

ꢀꢂ

is SW pin voltage.

is VIN pin voltage.

푆푊

푁_푃is the number of winding at the primary transformer.

푁_푆is the number of winding at the secondary transformer.

푉_푂푈푇is the Output voltage.

푉_퐹is the forward voltage of the secondary output diode.

VF

VOUT+

VOUT-

VIN

NS

NP

SDX/EN

SW

FB

REF GND

L_COMP

RFB

RREF

Figure 37. Application Block Diagram

The external resistor R_FBbetween the FB pin and the SW pin converts the primary flyback voltage into the FB pin

inflow current I_FB. I_FBis calculated by the formula below because the FB pin voltage is nearly equal to the VIN pin

voltage by IC’s internal circuit.

푁_푃

푁_푆

푁_푃

푁_푆

(

)

(

)

푉 +

ꢀꢂ

× 푉_푂푈푇+ 푉_퐹− 푉_퐹퐵

× 푉_푂푈푇+ 푉_퐹

푉

푆푊

− 푉_퐹퐵

퐼_퐹퐵

=

[A]

푅_퐹퐵

where:

퐼_퐹퐵is FB the pin inflow current.

푉_퐹퐵is FB pin voltage.

푅_퐹퐵is the external resistor between the FB pin and the SW pin.

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1

Output Voltage – continued

FB current I_RFBflows to the REF pin and the external resistor R_REFbetween the REF pin and the GND pin.

REF pin voltage is calculated by below equation.

푅_ꢃ퐸퐹푁_푃

( )

× 푉_푂푈푇+ 푉_퐹

푉_ꢃ퐸퐹

=

×

[V]

푅_퐹퐵

푁_푆

where:

푉_ꢃ퐸퐹is REF pin voltage.

푅_ꢃ퐸퐹is the external resistor between the REF pin and the GND pin.

R_REFresistor is necessary to set 2.7 kΩ because REF pin current is equivalent to I_REFand REF pin voltage is

equivalent to V_INTREF

.

0.54 ꢄ

푅_ꢃ퐸퐹

=

= ꢅ .7 푘훺

200 µ퐴

Therefore, the REF pin resistor is always needed to set R_REF= 2.7 kΩ .

The REF pin voltage is input to the comparator with the reference voltage V_INTREFin the IC. By the internal circuit, the

REF pin voltage is equal to the reference voltage. Therefore, the output voltage and the REF pin voltage is calculated

by the formula below.

푅_퐹퐵

푁_푆

[V]

푉_푂푈푇

=

×

× 푉

− 푉_퐹

ꢀꢂ푇ꢃ퐸퐹

푅_ꢃ퐸퐹푁_푃

To be shown to the equation, the output voltage is set by the number of winding ratio of the primary and secondary

transformer (N_P/N_S) and the resistance ratio of R_FBand R_REF. According to the relational expression in above, the

external resistor R_FBbetween the FB pin and the SW pin is calculated by the formula below.

푅_ꢃ퐸퐹

푁_푃

푁_푆

(

)

푅_퐹퐵

=

×

× 푉_푂푈푇+ 푉_퐹

[Ω]

푉

ꢀꢂ푇ꢃ퐸퐹

The ESR of the transformer on the secondary side as well as V_Fcauses the output voltage drop.

And, when transformer coupling is low, the N_P/ N_Sturns ratio changes and output voltage is lower than the setting

voltage. Therefore, adjust the output voltage by actual evaluation of power supply.

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Application Examples – continued

2

Transformer

2.1 The Determine of Winding Ratio N_P/ N_S

The winding ratio is the parameter for setting output voltage, Max output power, Duty, SW pin voltage.

The duty of flyback converter is calculated by the following equation:

푁_푃

푁_푆

(

)

× 푉_푂푈푇+ 푉_퐹

[%]

ꢆ푢푡푦 =

푁_푃

푁_푆

( )

× 푉_푂푈푇+ 푉_퐹

푉 +

ꢀꢂ

푁_푃is the Primary transformer winding

푁_푆is the Secondary transformer winding

푉_푂푈푇is the Output voltage

푉_퐹is the forward voltage of secondary output diode

푉

ꢀꢂ

is VIN pin voltage

The winding ratio is calculated by below equation.

푁_푃

ꢆ_푇푌푃

푉

ꢀꢂ

=

×

푁_푆1 − ꢆ_푇푌푃푉_푂푈푇+ 푉_퐹

ꢆ_푇푌푃is the Duty of VIN voltage (Typ)

In the middle VIN voltage of usual operating range, it recommends that D_TYPis set from 30 % to 50 %.

First, it recommends to set D_TYP= 40 %. The winding ratio is limited by the maximum duty(D_MAX) in minimum

input voltage condition. D_MAXgiven by the formula below must be not over 70 %. When duty is over 70 %,

change D_TYPto be lower. If Duty is over 70 %, OFF time is short and the output voltage may change due to the

shift in flyback voltage detection.

푉

푁_푃

ꢆ_푀퐴푋

ꢀꢂ(푀푖푛)

=

×

푁_푆1 − ꢆ_푀퐴푋푉_{푂푈푇(푀푎푥)}+ 푉_{퐹(푀푎푥)}

where:

ꢆ_푀퐴푋is the Maximum duty of minimum VIN voltage condition

푉_{푂푈푇(푀푎푥)}is the Maximum output voltage

푉_{퐹(푀푎푥)}is the Maximum forward voltage (V_F) of Secondary diode

Flyback voltage is calculated by below calculation.

푁_푃

[V]

(

)

푉_푂ꢃ= 푉_푂푈푇+ 푉_퐹×

푁_푆

SW pin voltage calculated below must be set so that the withstand voltage is not exceeded.

푉

푆푊

= 푉

+ 푉_푂ꢃ+ 푉

푆푈ꢃ퐺퐸

[V]

ꢀꢂ(푀푎푥)

For example, when it has the delating of 90 % for SW pin voltage, SW pin voltage is needed to be the value

which calculated 54 V or less.

( )

= 6ꢇ 푉 × 1ꢇꢇ % − 1ꢇ % = ꢈꢉ 푉

푉

푆푊

In the case of V_IN(Max)= 30 V and V_OR= 10 V, V_SURGEvoltage is needed to be 14 V or less. This value is calculated

below.

(

)

ꢈꢉ 푉 − 3ꢇ 푉 + 1ꢇ 푉 = 1ꢉ 푉

V_SURGEis occurred by the leakage of transformer. If V_SURGEis higher, it needs to decrease the voltage by

re-designing transformation structure or snubber circuit adjustment.

Voltage

V_SW

VSURGE

VOR

V_IN

Time

Figure 38. SW Waveform

When designed transformer, temporarily set winding ratio to satisfy above. When the winding ratio is decided,

R_FBcan be set and V_OUTalso can be set.

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2. Transformer – continued

2.2 The Calculation of L_P, L_S

The transformer should be set L_Pand L_Svalue that power supply works CCM operation.

For that, L_Pand Ls is determined to use “k” which is the indicator of CCM operation.

k is expressed from Figure 39 I_SPK, I_SBby the following equation.

푘 = (퐼_푆푃퐾− 퐼_푆퐵)/퐼_푆푃퐾

where:

퐼_푆푃퐾is the Secondary transformer peak current

퐼_푆퐵is the Secondary transformer bottom current

푘 is the Indicator of CCM ratio (It guides that it sets k = 0.25 when designing at first.)

I_PEAK

Primary

current

I_PPK

Secondary

current

I_PB

I_SPK

I_SB

time

Figure 39. The Waveform Example of Primary and Secondary Current of Transformer

where:

퐼_푃푃퐾is the Primary transformer peak current

퐼_푃퐵is the Primary transformer bottom current

I_LIMITshown in electric characteristics determines maximum primary peak current.

It enables to decide capable secondary minimum peak current from minimum I_LIMIT

.

푁_푃

[A]

퐼_{푆푃퐾ꢊ(푀푖푛)}= 퐼_{퐿ꢀ푀ꢀ푇(푀푖푛)}

×

푁_푆

Next, Ispk2(Max) is calculated from secondary maximum output current (I_OUT(Max)).

ꢅ × 퐼_{푂푈푇 푀푎푥}

1

휂

(

)

[A]

퐼_{푆푃퐾2 푀푎푥}

=

)

×

(

)

(

)

1 − ꢆ_푀퐴푋× ꢅ − 푘

휂 is the Efficiency of power supply, it recommends to set to about 70 %

In order to output I_OUT(Max), the condition of I_SPK2(Max)< I_SPK1(Min)must be satisfied.

If not satisfied, re-design to change k value. The higher the k value, the wider the load area of DCM

(Discontinuous Conduction Mode) operation. k = 1 means that the operation is DCM at all loads. IC has

advantage of fast response and low EMI characteristics in CCM operation. For that, k is recommended lower

value. Even if k value is high, there is no problem to output voltage regulation operation.

The secondary inductance L_S(Max)is calculated by the following equation.

2

(

)

(

)

ꢅ − 푘 × 푉_푂푈푇+ 푉_퐹× (1 − ꢆ_푀퐴푋

)

ꢁ_{푆(푀푎푥)}

=

[µH]

ꢅ × 퐼_{푂푈푇(푀푎푥)}× 푓

× 푘

푆푊(푀푎푥)

is the Switching frequency (f_SW(Max)is set to 430 kHz in IC)

)

where:

푓

(

푆푊 푀푎푥

퐼_{푂푈푇 푀푎푥}is the Maximum secondary output current

(

)

Primary inductance L_Pis calculated by below.

푁_푃

푁_푆

2

ꢁ_푃= ꢁ_푆× (

)

[µH]

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2. Transformer – continued

2.3 The Calculation of I_PRMSand I_SRMS

Maximum primary RMS current (I_PRMS) and Maximum secondary RMS current (I_SRMS) are calculated below.

(퐼_푃푃퐾²+ 퐼_푃푃퐾× 퐼_푃퐵+ 퐼_푃퐵²) × ꢆ_푀퐴푋

[A]

√

=

퐼_푃ꢃ푀푆

3

2

ꢋ퐼_푆푃퐾+ 퐼_푆푃퐾× 퐼_푆퐵+ 퐼_푆퐵²ꢌ × (1 − ꢆ_푀퐴푋

)

[A]

√

=

퐼_푆ꢃ푀푆

3

When selecting the wire diameter of transformer, refer to this RMS current.

3

Output Capacitor

The output capacitor place as close to the secondary diode as possible. Output capacitor value C_OUTis needed to set

from the output ripple voltage (ΔV_O) and start-up time. The output ripple voltage which occurs by switching is

calculated by below equation.

퐼_{푂푈푇(푀푎푥)}× ꢆ_푀퐴푋

훥푉_푂=

[V]

푓_{푆푊(푀푎푥)}× 퐶_푂푈푇

On the other hand, when output capacitor is large, start-up time is long.

When SCP detection mask time (t_MASKSCP) in start-up is passed, if REF voltage is lower than V_SCP, power supply

cannot output. Therefore, C_OUTmust be satisfied below condition.

푁_푃

푁_푆

( )

ꢏ × 1 − ꢆ푢푡푦 − 퐼_{푂푈푇 푀푎푥}}

( )

푡_{푀퐴푆퐾푆ꢍ푃(푀푖푛)}× {ꢎ퐼_{퐿ꢀ푀ꢀ푇 푀푖푛}

×

푉

(

)

1

퐶_푂푈푇≤ ×

ꢅ

푉

[µF]

푆ꢍ푃(푀푎푥)

푉_푂푈푇× (

)

ꢀꢂ푇ꢃ퐸퐹(푀푖푛)

푽

푺푪푷(푴풂풙)

Here,

= 0.762

푽

푰푵푻푹푬푭(푴풊풏)

A large output capacitance is required to hold the output voltage for load response or input voltage response. As a

guide for output capacitor, it recommends the capacitance of 20 µF or more. And ceramic capacitor may be lower

capacitance because of temperature characteristics and variance, DC bias characteristics. It needs to select the parts

to care them.

4

Input Capacitor

It uses ceramic capacitor to input capacitor and it is placed as close to the IC as possible.

The capacitor value is set 10 µF or more.

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Application Examples – continued

5

Secondary Output Diode

Because the forward voltage (V_F) of secondary output diode causes an error in the output voltage, it needs to use SBD

or FRD which is low forward voltage (V_F). and the peak of diode reverse voltage must not exceed the rating of the

diode. The secondary RMS current must be set that it does not exceed the rating current. Generally, it is

recommended that the reverse voltage of secondary output diode sets to have margin of 30 % or more.

푁_푆

[V]

푉_ꢃ= (푉

×

+ 푉_푂푈푇) × 1.3 + 푉

푆푈ꢃ퐺퐸

ꢀꢂ(푀푎푥)

푁_푃

where:

푉_ꢃis the reverse voltage of secondary output diode

is VIN maximum pin voltage

푉

ꢀꢂ(푀푎푥)

푁_푃is the primary winding turns of transformer

푁_푆is the secondary winding turns of transformer

푉_푂푈푇is the Output voltage

푉

푆푈ꢃ퐺퐸

is the Surge voltage of transformer generated to the diode

And it is recommended that rating current of output diode margin twice or more for I_SRMS

.

6

Output Resistor and Output Zener Diode (Minimum Load Current)

The output voltage raises in no load or light load. This is the reason IC is always worked by the minimum switching

frequency which is determined by maximum OFF time t_{OFF_MAX}and minimum ON time t_{ON_MIN}at light loads.

Because power supply supplies minimum power P_OMINby this minimum switching frequency, output voltage raises

when secondary power is lighter than P_{O_MIN}. P_{O_MIN}is calculated by below.

ꢖ

ꢄ

ꢊ

ꢑꢒ(ꢓꢔꢕ)

2

ꢐ_{푂_푀ꢀꢂ}

=

× 푡_{푂ꢂ_푀ꢀꢂ(푀푎푥)}×

ꢘ

ꢙꢒ_ꢓꢑꢒ(ꢓꢔꢕ)

[W]

2×퐿

ꢚꢘ

ꢗ

ꢙꢛꢛ_ꢓꢜꢝ(ꢓꢞꢟ)

푃

ꢙ_ꢓꢑꢒ

퐼_{푂푈푇_푀ꢀꢂ}

=

By the equation, I_{OUT_MIN}can be also calculated.

ꢄ

ꢙꢠꢡ

When the raise of secondary output voltage is unacceptable, it needs to connect zener diode to secondary output. It

operates output voltage suppression less than zener diode voltage.

And it can prevent to rise output voltage by losses which is occurred to connect resistors to secondary output. The

secondary load resistor R_OUTis less than below equation is needed. Secondary resistor loss is calculated by the

equation.

ꢖ

ꢄ

ꢙꢠꢡ

[W]

ꢐ_퐿푂푆푆

=

ꢃ

ꢙꢠꢡ

2

푉_푂푈푇

×

푅_푂푈푇

≤

=

[Ω]

2

ꢐ_{푂_푀ꢀꢂ}

푉

1

ꢀꢂ(푀푎푥)

2

× 푡_{푂ꢂ_푀ꢀꢂ(푀푎푥)}

ꢅ × ꢁ_푃

푡_{푂ꢂ_푀ꢀꢂ(푀푎푥)}+ 푡_{푂퐹퐹_푀퐴푋(푀푖푛)}

In fact, even if R_OUTresistance which is calculated above equation is used, output voltage rises transiently in switching

OFF time. For that, R_OUTshould be set low enough. R_OUTneeds to adjust through evaluation. R_OUTresistor is needed to

notice power dissipation.

The reason of output voltage raise refers to Application Examples: “10.The Influence on Frequency and Output Voltage

for Each Load”.

VF

VOUT

Np

Ns

R_OUT

Figure 40. Zener Diode and Resistor to Secondary Output

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Application Examples – continued

7

Snubber Circuit

When the combination degree of transformer is low or large current line of board is long, the large surge voltage

may be occurred in the SW pin at turn OFF timing of MOSFET. Preventing it, the snubber circuit shown in figure 41 is

used. This snubber circuit clamps fly-back voltage + surge voltage when the voltage exceeds snubber voltage.

VF

Vz

VOUT

Np

Ns

V_F2

Figure 41. Snubber Circuit

The clamp voltage is determined the following equation.

푉_{ꢍ퐿퐴푀푃}= 푉_퐹2+ 푉

[V]

푧

where:

푉_{ꢍ퐿퐴푀푃}is the Clamp setting voltage of snubber circuit

푉_퐹2is the Forward voltage of SBD

푉 is the Zener diode voltage

푧

ꢂ

ꢗ

( )

× 푉_푂푈푇+ 푉_퐹), large current flows to

When the clamp setting voltage is lower than flyback voltage ( equal to

ꢂ

ꢢ

Zener diode in the turn off. Therefore, the snubber voltage (V_CLAMP) must be higher than flyback voltage.

When snubber circuit is slow response, it may not clamp setting voltage.

So, SW voltage must be evaluated.

8

Setting of SDX/EN Pin Resistor

8.1 Setting of Enable Voltage

It can set enable voltage V_{IN_ENABLE}by following equation after releasing VIN UVLO.

푅_ꢊ+ (푅₂//푅_{푆퐷푋/퐸ꢂ}

푅₂//푅_{푆퐷푋/퐸ꢂ}

)

[V]

푉

= 푉_퐸ꢂꢊ×

ꢀꢂ_퐸ꢂ퐴퐵퐿퐸

where:

푉

is the Target VIN operating start voltage

ꢀꢂ_퐸ꢂ퐴퐵퐿퐸

푉_퐸ꢂꢊis the Enable voltage 1

푅₂//푅_{푆퐷푋/퐸ꢂ}is the Divided resistor between R₂and R_SDX/ENwhich is IC internal resistor

V_IN

R₁

VIN

SDX/EN

R₂

R_SDX/EN

Figure 42. Resistors Connected to the SDX/EN Pin

8.2 Setting of disabled Voltage

It can set disable voltage V_{IN_DISABLE}at VIN pin voltage falling by following equation.

푅_ꢊ+ (푅₂//푅_{푆퐷푋/퐸ꢂ}

푅₂//푅_{푆퐷푋/퐸ꢂ}

)

[V]

푉

= 푉_퐸ꢂ2×

ꢀꢂ_퐷ꢀ푆퐴퐵퐿퐸

where:

푉

is the Target VIN operating stop voltage

ꢀꢂ_퐷ꢀ푆퐴퐵퐿퐸

푉_퐸ꢂ2is the Enable voltage2

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Application Examples – continued

9

The Output Voltage Compensation Function by L_COMP Pin Resistor

This IC is built in output voltage compensation function which is prevented that output voltage decrease when

primary transformer peak current (I_P) increase. The cause of the drop of output voltage V_OUTare the forward voltage

change of secondary diode and transformer leakage etc.

The example of output voltage compensation is shown in Figure 43.

V_OUT

With Load compensation

No load compensation

I_OUT

Figure 43. L_COMP Voltage Compensation Example

This function compensates the output voltage by increasing I_REFCOMPcurrent to the REF current that determines the

output voltage.

ꢂ

ꢄ

ꢢ

푉_푂푈푇= 푅_퐹퐵

×

× ꢎ ^{ꢑꢒꢡꢣꢤꢛ}+ 퐼_{ꢃ퐸퐹ꢍ푂푀푃}ꢏ − 푉_퐹

[V]

ꢂ

ꢃ

ꢣꢤꢛ

ꢗ

ꢄ

ꢑꢒꢡꢣꢤꢛ

REF current

is fiexed to 200 µA (Typ). I_REFCOMPis increased for primary current increasing. As the result,

ꢃ

ꢣꢤꢛ

output voltage is compensated by output current on the secondary side.

I_REFCOMPis calculated to below.

퐼_{ꢃ퐸퐹ꢍ푂푀푃}= 푅_{퐿_ꢍ푂푀푃}× ꢥ_{퐿_ꢍ푂푀푃}× 퐼_{푆푊(퐴푣푒)}

[µA]

where:

푅_{퐿_ꢍ푂푀푃}is the Resistor connected to the L_COMP pin

퐼_{푆푊(퐴푣푒)}is the Averaging current flown to the SW pin

ꢥ_{퐿_ꢍ푂푀푃}is the Fixed value determined by IC

Averaging current I_SW(Ave)of the SW pin can be converted below.

푁_푆

푁_푃

1

= 퐼_푂푈푇× ×

휂

푁_푆

푁_푃

퐼_{푆푊(퐴푣푒)}= 퐼_{푆(퐴푣푒)}

×

[A]

where:

휂 is the efficiency (It recommends 70 % in design. And adjust R_{L_COMP}in application evaluation.)

Because I_SW(Ave)is proportional to I_OUTas shown in the above equation, it enables to compensate output voltage. The

compensation degree can adjust by resistor value of the L_COMP pin.

Because I_SWis triangle wave current, connect the capacitor 0.1 µF or more at the L_COMP pin to flatten it.

The resistor value of the L_COMP pin is calculated by the following equation.

퐼_{ꢃ퐸퐹ꢍ푂푀푃}

1

푅_{퐿_ꢍ푂푀푃}

=

×

[kΩ]

퐼_{푆푊(퐴푣푒)}ꢥ_{퐿_ꢍ푂푀푃}

Be sure to evaluate the output voltage characteristics in the application and adjust L_COMP resistance as necessary.

And, if the function is no use, the L_COMP pin is needed to connect to GND.

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Application Examples – continued

10 The Influence on Frequency and Output Voltage for Each Load

This IC enables high efficiency to be lower switching frequency in light load. In CCM operation, the switching

frequency is f_SWfor a constant load. When the load is light, the operation is changed from CCM operation to DCM

operation. Then, switching frequency is reduced from f_SW

.

The output load I_{OUT_ SW1}is calculated below.

f

2

(

)

푉 × ꢆ푢푡푦

ꢀꢂ

1

퐼_{푂푈푇_ 푆푊ꢊ}

푓

= ×

× 휂

[A]

ꢅ

ꢁ_푃× 푓 × 푉_푂푈푇

푆푊

where:

퐼_{푂푈푇_ 푆푊ꢊ}

푓

is the Switched output current from DCM to CCM

푓

푉

ꢀꢂ

is the Switching frequency

is VIN pin voltage

푆푊

ꢁ_푃is the Primary inductance

푉_푂푈푇is the Output voltage

휂 is the Efficiency

As the load is further lightened, the ON time and OFF time decreases. ON time is operated by t_{ON_MIN}

The load current operated by t_{ON_MIN}is below.

.

1

= ×

ꢅ

푓

푆푊

× ꢋ푉 × 푡_{푂ꢂ_푀ꢀꢂ}ꢌ²

ꢀꢂ

퐼_{푂푈푇_ 푆푊2}

푓

× 휂

[A]

ꢁ_푃× 푉_푂푈푇

where:

퐼_{푂푈푇_ 푆푊2}

푓

is the Load current operated by minimum ON time

푡_{푂ꢂ_푀ꢀꢂ}is the Minimum ON time

As the load is further lightened, the ON time is not shorter than the t_{ON_MIN}and the OFF time is longer.

Because IC is determined maximum OFF time,

f_{SW_MIN}is calculated to below.

1

푓

=

[kHz]

푆푊_푀ꢀꢂ

푡_{푂ꢂ_푀ꢀꢂ}+ 푡_{푂퐹퐹_푀퐴푋}

where:

푓

is the Minimum switching frequency

푆푊_푀ꢀꢂ

푡_{푂퐹퐹_푀퐴푋}is the Maximum OFF time

Therefore, constant output power is generated by f_{SW_MIN}operation in no load or light load.

For that, output voltage raises in no load or light load.

And the IC builds in frequency spectrum spread function for EMI improvement. For that, the switching frequency is

changed within a constant rate. An output voltage ripple which is dependent on spectrum spread occurs by the

function.

SwitchingFrequency

f_SW

Frequency

Spectrum Spread

f_{SW _MIN}

I_{OUT_MIN}

I_{OUT_ SW 2}

I_{OUT_ SW 1}

I_OUT

f

Figure 44. Switching Frequency

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I/O Equivalence Circuits

1

GND

2

SDX/EN

3

L_COMP

4

REF

Internal

Supply

GND

SDX/EN

REF

L_COMP

GND

R_SDX/EN

GND

SW

VIN

5

FB

6

7

8

N.C.

VIN

SW

VIN

FB

GND

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Operational Notes

1. Reverse Connection of Power Supply

Connecting the power supply in reverse polarity can damage the IC. Take precautions against reverse polarity when

connecting the power supply, such as mounting an external diode between the power supply and the IC’s power

supply pins.

2. Power Supply Lines

Design the PCB layout pattern to provide low impedance supply lines. Furthermore, connect a capacitor to ground at

all power supply pins. Consider the effect of temperature and aging on the capacitance value when using electrolytic

capacitors.

3. Ground Voltage

Ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition.

4. Ground Wiring Pattern

When using both small-signal and large-current ground traces, the two ground traces should be routed separately but

connected to a single ground at the reference point of the application board to avoid fluctuations in the small-signal

ground caused by large currents. Also ensure that the ground traces of external components do not cause variations

on the ground voltage. The ground lines must be as short and thick as possible to reduce line impedance.

5. Recommended Operating Conditions

The function and operation of the IC are guaranteed within the range specified by the recommended operating

conditions. The characteristic values are guaranteed only under the conditions of each item specified by the electrical

characteristics.

6. Inrush Current

When power is first supplied to the IC, it is possible that the internal logic may be unstable and inrush current may flow

instantaneously due to the internal powering sequence and delays, especially if the IC has more than one power

supply. Therefore, give special consideration to power coupling capacitance, power wiring, width of ground wiring, and

routing of connections.

7. Testing on Application Boards

When testing the IC on an application board, connecting a capacitor directly to a low-impedance output pin may

subject the IC to stress. Always discharge capacitors completely after each process or step. The IC’s power supply

should always be turned off completely before connecting or removing it from the test setup during the inspection

process. To prevent damage from static discharge, ground the IC during assembly and use similar precautions during

transport and storage.

8. Inter-pin Short and Mounting Errors

Ensure that the direction and position are correct when mounting the IC on the PCB. Incorrect mounting may result in

damaging the IC. Avoid nearby pins being shorted to each other especially to ground, power supply and output pin.

Inter-pin shorts could be due to many reasons such as metal particles, water droplets (in very humid environment) and

unintentional solder bridge deposited in between pins during assembly to name a few.

9. Unused Input Pins

Input pins of an IC are often connected to the gate of a MOS transistor. The gate has extremely high impedance and

extremely low capacitance. If left unconnected, the electric field from the outside can easily charge it. The small

charge acquired in this way is enough to produce a significant effect on the conduction through the transistor and

cause unexpected operation of the IC. So unless otherwise specified, unused input pins should be connected to the

power supply or ground line.

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Operational Notes – continued

10. Regarding the Input Pin of the IC

This monolithic IC contains P+ isolation and P substrate layers between adjacent elements in order to keep them

isolated. P-N junctions are formed at the intersection of the P layers with the N layers of other elements, creating a

parasitic diode or transistor. For example (refer to figure below):

When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode.

When GND > Pin B, the P-N junction operates as a parasitic transistor.

Parasitic diodes inevitably occur in the structure of the IC. The operation of parasitic diodes can result in mutual

interference among circuits, operational faults, or physical damage. Therefore, conditions that cause these diodes to

operate, such as applying a voltage lower than the GND voltage to an input pin (and thus to the P substrate) should be

avoided.

Resistor

Transistor (NPN)

Pin A

Pin B

B

E

C

Pin A

B

C

E

P

P⁺

N

P⁺

P

P⁺

N

Parasitic

Elements

Parasitic

Elements

P Substrate

GND GND

P Substrate

GND

Parasitic

Elements

Parasitic

Elements

N Region

close-by

Figure 45. Example of Monolithic IC Structure

11. Ceramic Capacitor

When using a ceramic capacitor, determine a capacitance value considering the change of capacitance with

temperature and the decrease in nominal capacitance due to DC bias and others.

12. Thermal Shutdown Circuit (TSD)

This IC has a built-in thermal shutdown circuit that prevents heat damage to the IC. Normal operation should always

be within the IC’s maximum junction temperature rating. If however the rating is exceeded for a continued period, the

junction temperature (Tj) will rise which will activate the TSD circuit that will turn OFF power output pins. When the Tj

falls below the TSD threshold, the circuits are automatically restored to normal operation.

Note that the TSD circuit operates in a situation that exceeds the absolute maximum ratings and therefore, under no

circumstances, should the TSD circuit be used in a set design or for any purpose other than protecting the IC from

heat damage.

13. Over Current Protection Circuit (OCP)

This IC incorporates an integrated overcurrent protection circuit that is activated when the load is shorted. This

protection circuit is effective in preventing damage due to sudden and unexpected incidents. However, the IC should

not be used in applications characterized by continuous operation or transitioning of the protection circuit.

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Ordering Information

B D 7

F

2

0

5 E F

J

-

CE2

Package

Product Class

EFJ: HTSOP-J8

C: for Automotive

Packaging and Forming Specification

E2: Embossed Tape and Reel (HTSOP-J8)

Marking Diagram

HTSOP-J8 (TOP VIEW)

Part Number Marking

LOT Number

D 7 F 2 0 5

Pin 1 Mark

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Physical Dimension and Packing Information

Package Name

HTSOP-J8

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BD7F205EFJ-C

Revision History

Date

Revision

001

Changes

New Release

19.May.2022

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Notice

Precaution on using ROHM Products

(Note 1)

1. If you intend to use our Products in devices requiring extremely high reliability (such as medical equipment

,

aircraft/spacecraft, nuclear power controllers, etc.) and whose malfunction or failure may cause loss of human life,

bodily injury or serious damage to property (“Specific Applications”), please consult with the ROHM sales

representative in advance. Unless otherwise agreed in writing by ROHM in advance, ROHM shall not be in any way

responsible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of any

ROHM’s Products for Specific Applications.

(Note1) Medical Equipment Classification of the Specific Applications

JAPAN

USA

EU

CHINA

CLASSⅢ

CLASSⅣ

CLASSⅡb

CLASSⅢ

2. ROHM designs and manufactures its Products subject to strict quality control system. However, semiconductor

products can fail or malfunction at a certain rate. Please be sure to implement, at your own responsibilities, adequate

safety measures including but not limited to fail-safe design against the physical injury, damage to any property, which

a failure or malfunction of our Products may cause. The following are examples of safety measures:

[a] Installation of protection circuits or other protective devices to improve system safety

[b] Installation of redundant circuits to reduce the impact of single or multiple circuit failure

3. Our Products are not designed under any special or extraordinary environments or conditions, as exemplified below.

Accordingly, ROHM shall not be in any way responsible or liable for any damages, expenses or losses arising from the

use of any ROHM’s Products under any special or extraordinary environments or conditions. If you intend to use our

Products under any special or extraordinary environments or conditions (as exemplified below), your independent

verification and confirmation of product performance, reliability, etc, prior to use, must be necessary:

[a] Use of our Products in any types of liquid, including water, oils, chemicals, and organic solvents

[b] Use of our Products outdoors or in places where the Products are exposed to direct sunlight or dust

[c] Use of our Products in places where the Products are exposed to sea wind or corrosive gases, including Cl2,

H2S, NH3, SO2, and NO2

[d] Use of our Products in places where the Products are exposed to static electricity or electromagnetic waves

[e] Use of our Products in proximity to heat-producing components, plastic cords, or other flammable items

[f] Sealing or coating our Products with resin or other coating materials

[g] Use of our Products without cleaning residue of flux (Exclude cases where no-clean type fluxes is used.

However, recommend sufficiently about the residue.); or Washing our Products by using water or water-soluble

cleaning agents for cleaning residue after soldering

[h] Use of the Products in places subject to dew condensation

4. The Products are not subject to radiation-proof design.

5. Please verify and confirm characteristics of the final or mounted products in using the Products.

6. In particular, if a transient load (a large amount of load applied in a short period of time, such as pulse, is applied,

confirmation of performance characteristics after on-board mounting is strongly recommended. Avoid applying power

exceeding normal rated power; exceeding the power rating under steady-state loading condition may negatively affect

product performance and reliability.

7. De-rate Power Dissipation depending on ambient temperature. When used in sealed area, confirm that it is the use in

the range that does not exceed the maximum junction temperature.

8. Confirm that operation temperature is within the specified range described in the product specification.

9. ROHM shall not be in any way responsible or liable for failure induced under deviant condition from what is defined in

this document.

Precaution for Mounting / Circuit board design

1. When a highly active halogenous (chlorine, bromine, etc.) flux is used, the residue of flux may negatively affect product

performance and reliability.

2. In principle, the reflow soldering method must be used on a surface-mount products, the flow soldering method must

be used on a through hole mount products. If the flow soldering method is preferred on a surface-mount products,

please consult with the ROHM representative in advance.

For details, please refer to ROHM Mounting specification

Notice-PAA-E

Rev.004

Precautions Regarding Application Examples and External Circuits

1. If change is made to the constant of an external circuit, please allow a sufficient margin considering variations of the

characteristics of the Products and external components, including transient characteristics, as well as static

characteristics.

2. You agree that application notes, reference designs, and associated data and information contained in this document

are presented only as guidance for Products use. Therefore, in case you use such information, you are solely

responsible for it and you must exercise your own independent verification and judgment in the use of such information

contained in this document. ROHM shall not be in any way responsible or liable for any damages, expenses or losses

incurred by you or third parties arising from the use of such information.

Precaution for Electrostatic

This Product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. Please take proper

caution in your manufacturing process and storage so that voltage exceeding the Products maximum rating will not be

applied to Products. Please take special care under dry condition (e.g. Grounding of human body / equipment / solder iron,

isolation from charged objects, setting of Ionizer, friction prevention and temperature / humidity control).

Precaution for Storage / Transportation

1. Product performance and soldered connections may deteriorate if the Products are stored in the places where:

[a] the Products are exposed to sea winds or corrosive gases, including Cl₂, H₂S, NH₃, SO₂, and NO₂

[b] the temperature or humidity exceeds those recommended by ROHM

[c] the Products are exposed to direct sunshine or condensation

[d] the Products are exposed to high Electrostatic

2. Even under ROHM recommended storage condition, solderability of products out of recommended storage time period

may be degraded. It is strongly recommended to confirm solderability before using Products of which storage time is

exceeding the recommended storage time period.

3. Store / transport cartons in the correct direction, which is indicated on a carton with a symbol. Otherwise bent leads

may occur due to excessive stress applied when dropping of a carton.

4. Use Products within the specified time after opening a humidity barrier bag. Baking is required before using Products of

which storage time is exceeding the recommended storage time period.

Precaution for Product Label

A two-dimensional barcode printed on ROHM Products label is for ROHM’s internal use only.

Precaution for Disposition

When disposing Products please dispose them properly using an authorized industry waste company.

Precaution for Foreign Exchange and Foreign Trade act

Since concerned goods might be fallen under listed items of export control prescribed by Foreign exchange and Foreign

trade act, please consult with ROHM in case of export.

Precaution Regarding Intellectual Property Rights

1. All information and data including but not limited to application example contained in this document is for reference

only. ROHM does not warrant that foregoing information or data will not infringe any intellectual property rights or any

other rights of any third party regarding such information or data.

2. ROHM shall not have any obligations where the claims, actions or demands arising from the combination of the

Products with other articles such as components, circuits, systems or external equipment (including software).

3. No license, expressly or implied, is granted hereby under any intellectual property rights or other rights of ROHM or any

third parties with respect to the Products or the information contained in this document. Provided, however, that ROHM

will not assert its intellectual property rights or other rights against you or your customers to the extent necessary to

manufacture or sell products containing the Products, subject to the terms and conditions herein.

Other Precaution

1. This document may not be reprinted or reproduced, in whole or in part, without prior written consent of ROHM.

2. The Products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written

consent of ROHM.

3. In no event shall you use in any way whatsoever the Products and the related technical information contained in the

Products or this document for any military purposes, including but not limited to, the development of mass-destruction

weapons.

4. The proper names of companies or products described in this document are trademarks or registered trademarks of

ROHM, its affiliated companies or third parties.

Notice-PAA-E

Rev.004


型号：	BD7F205EFJ-C (新产品)
厂家：	ROHM
描述：	BD7F205EFJ-C是不需要光耦的隔离型反激式转换器。该产品不需要由光电耦合器或变压器辅助绕组组成的反馈电路，有助于削减应用产品的部件数量。另外，该产品还通过采用ROHM自有的自适应导通时间控制技术，实现了高速负载响应。此外，还具有多种保护功能，可提高隔离型电源应用设计的可靠性。变压器光电转换器
文件：	总35页 (文件大小：1227K)
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