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July 2016

FL77905

Analog / PWM / Phase-cut Dimmable Compact LED

Direct AC Driver

Features

Description

The FL77905 is a direct AC line LED driver with minimal

number of external RC passive components. In normal

configuration, one resistor is to adjust LED power, and

one capacitor is to provide a stable voltage to an

internal biasing shunt regulator.

.

The simplest Direct AC LED Driver with Only Two

External RC Passive Components

.

Wide AC Input Range : 90~305 V_AC

Three Integrated High-Voltage LED Constant

Current Sinks of up to 75 mA (RMS) Capability

The FL77905 provides phase-cut dimming with wide

dimming range, smooth dimming control and good

dimmer compatibility. It achieves high efficiency with

high PF and low THD which makes the FL77905

suitable for high-efficiency LED lighting systems. The

FL77905 can also be used with a rheostat dimmer

switches which are suitable for desktop or indoor lamps.

.

TRIAC Dimmable (Leading/Trailing Edge)

Rheostat Dimmable

Analog/Digital PWM Dimming Function

High Power Factor (above 0.98 in normal

configuration)

The FL77905 has a dedicated DIM pin which is

designed to be used with analog or digital PWM

dimming.

.

Adjustable LED Power with an External Current

Sense Resistor

Low Harmonic Content (THD under 20% in Normal

Configuration)

Operation of FL77905 admits driving higher-wattage

systems, such as street lights and down lights, by

simply parallel connecting the driver ICs.

.

Compact SOIC 8-Lead Package

Flexible LED Forward Voltage Configuration

Power Scalability with Multiple Driver ICs

Over-Temperature Protection (OTP)

Applications

.

General LED Driving Solution for Residential,

Commercial and Industrial Lighting

Ordering Information

Operating

Temperature Range

Packing

Part Number

Package

Method

8-Lead, Small Outline Integrated Circuit

(SOIC) JEDEC MS012 150” Narrow Body,

Exposed Pad

FL77905MX

-40 to 125°C

2,500 per Reel

FL77905 • Rev. 1.0

www.fairchildsemi.com

Typical Application

2K

Bridge

Rectifier

VIN

VDD

DIM

Fuse

LED1

LED2

LED3

C_VDD

0.1µF, 50V

To

dimming

signal

CS

GND

Forward voltage (V_F)

across each LED group

is adjustable as desired.

R_CS

1%

GND

Figure 1.

Typical Application Schematic

Block Diagram

VIN

2

3

LED1

LED2

LED3

LED Current

Modulator

Shunt

Regulator

8

VDD

4

5

Over-

Temperature

Protection

LED

Current

Feedback

DIM

1

6

7

GND

CS

Figure 1.

Simplified Block Diagram

FL77905 • Rev. 1.0

www.fairchildsemi.com

2

Pin Configuration

1

2

3

4

8

7

6

5

VDD

CS

DIM

VIN

LED1

LED2

GND

LED3

Figure 2.

Pin Configuration (Top View)

Thermal Characteristics ^{(1) (2)}

_JA

(1S PCB)

_JA

(2S2P PCB)

Component

Package

Unit

8-Lead, Small Outline Integrated Circuit (SOIC)

JEDEC MS012 150” Narrow Body, Exposed Pad

FL77905MX

156

37

°C/W

Notes:

1. Θ_JA: Thermal resistance between junction and ambient, dependent on the PCB design, heat sinking, and airflow.

The value given is for natural convection with no heatsink using the 1S and 2S2P boards, as specified in JEDEC

standards JESD51-2, JESD51-5, and JESD51-7, as appropriate.

2. Junction-to-air thermal resistance is highly dependent on application and PCB layout. In application where the

device dissipates high levels of power during operation, special care of thermal dissipation issues in PCB design

must be taken.

Pin Definitions

Pin#

Name

Description

Dimming Signal Input Pin. This pin is used to further adjust LED current of a given R_CS

value. Apply 0 V to 5 V as the DIM signal. Both analog and digital PWM signal can be used.

1

DIM

Rectified AC Input Voltage. Connect this pin to rectified AC voltage after a bridge rectifier.

2

3

4

5

VIN

LED1

LED2

LED3

LED String Cathodes. Connect cathode(s) of each LED group to these pins.

Ground Reference Pin. Tie this pin directly to local ground plane. This ground should not be

tied to earth ground because it is not isolated from AC mains.

6

7

GND

CS

LED Current Sense Pin. Limits the LED current depending on voltage across sensing

resistor. The CS pin is used to set the LED current regulation target.

Internal Biasing Shunt Regulator Output. Voltage on this pin supplies internal circuitry of

FL77905. A 17-V shunt regulator is internally connected to this pin. A bypassing capacitor is

recommended to be added to reduce noise from VIN.

8

0

VDD

EP

Exposed Thermal Pad. EP is not tied to GND inside the IC. It is recommended to tie it to

GND externally.

FL77905 • Rev. 1.0

www.fairchildsemi.com

3

Absolute Maximum Ratings

Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be

operable above the recommended operating conditions and stressing the parts to these levels is not recommended.

In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability.

The absolute maximum ratings are stress ratings only.

Symbol

V_IN

Parameter

Min.

-0.3

-55

Max.

500.0

200.0

6.0

Unit

V

VIN Voltage

V_LED1

V_LED2

V_LED3

V_CS

LED1 Pin Voltage

LED2 Pin Voltage

LED3 Pin Voltage

CS Pin Voltage

DIM Pin Voltage

Junction Temperature

Storage Temperature

LED1 Current

V

V_DIM

T_J

6.0

V

+150

80

ºC

mA

T_STG

I_LED1

I_LED2

I_LED3

-65

LED2 Current

100

LED3 Current

150

Notes:

3. Stress beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device.

4. All voltage values, except differential voltages, are given with respect to the GND pin.

5. Human Body Model, ANSI/ESDA/JEDEC JS-001-2012: 1.0 kV at Pins 2~4, 0.4 kV at Pin 5, 1.5 kV at Pins 1,

7~8.

6. Charged Device Model, JESD22-C101: 1.0 kV at Pins 1~8.

Recommended Operating Conditions

The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended

operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not

recommend exceeding them or designing to Absolute Maximum Ratings.

Symbol

Parameter

Operating Junction Temperature

Min.

Max.

Unit

T_J

-40

+125

°C

FL77905 • Rev. 1.0

www.fairchildsemi.com

4

Electrical Characteristics

Unless otherwise noted, R_CS= 10 Ω, T_A= 25°C. Currents are defined as positive into the device and negative out of

the device.

Symbol

Parameter

Conditions

Min. Typ. Max. Unit

VIN Supply

I_QUIES.VIN

VDD Output

V_DD

VIN Quiescent Current

VDD Voltage

V_IN= 500 V Max.

0.75

17

1.20

18

mA

V

V_IN= 20.0 V

16

LED Current

I_LED1

LED1 Current

LED2 Current

LED3 Current

V_IN= 20.0 V, V_LED1= 20.0 V

V_IN= 20.0 V, V_LED2= 35.0 V

V_IN= 20.0 V, V_LED3= 20.0 V

40.4

78.2

87.8

47.0

86.0

53.6

93.8

mA

I_LED2

I_LED3

96.0 104.2

Over-Temperature Protection

T_OTP

OTP Temperature⁽⁷⁾

Leakage Current

170

°C

I_LED1-LK

I_LED2-LK

I_LED3-LK

LED1 Leakage Current

V_LED1= 500 V, V_IN= 0 V

V_LED2= 500 V, V_IN= 0 V

V_LED3= 200 V, V_IN= 0 V

1

µA

LED2 Leakage Current

LED3 Leakage Current

Note:

7. Not tested in production. Internal over-temperature protection circuitry protects the device from permanent

damage. LEDs shut down at the junction temperature of T_J=170°C (typical).

FL77905 • Rev. 1.0

www.fairchildsemi.com

5

Typical Performance Characteristics

1.03

1.02

1.01

1

1.2

1.15

1.1

1.05

1

0.95

0.9

0.99

0.98

0.97

0.85

0.8

-40 -20

0

25 40 60 80 100 120 140

Temperature(ºC)

-40 -20

0

25 40 60 80 100 120 140

Temperature(ºC)

Figure 3.

I_QUIES.VINvs. Temperature

Figure 4.

V_DDvs. Temperature

1.003

1.002

1.001

1

1.01

1.005

1

0.999

0.998

0.997

0.995

0.99

-40 -20

0

25 40 60 80 100 120 140

-40 -20

0

25 40 60 80 100 120 140

Temperature(ºC)

Figure 5.

I_LED1vs. Temperature

Figure 6.

I_LED2vs. Temperature

1.003

1.002

1.001

1

0.999

0.998

0.997

-40 -20

0

25

40

60

80 100 120 140

Temperature(ºC)

Figure 7.

I_LED3vs. Temperature

FL77905 • Rev. 1.0

www.fairchildsemi.com

6

Functional Description

The FL77905 can drive LED strings attached directly to

the rectified AC mains using only two external RC

components (R_CSand C_VDD). With three integrated high

voltage current sink, LED current in each string is

precisely controlled with system compactness. High PF

and low THD are obtained by the optimized current sink

levels. Phase-cut dimming is easily obtained with wide

dimming range and good dimmer compatibility.

Dedicated DIM pin is used to implement analog or

digital dimming function. Flicker index in the direct AC

drive topology can be improved by adopting proprietary

self valley-fill solution.

than 0.98 and THD is lower than 20%. The efficiency

heavily depends on a LED configuration.

LED Current and Power Setting

The LED current is managed by an external current

sense resistor R_CS. Regulation target of each channel's

current sink is calculated as follows:

0.47

0.86

0.96

I_LED1



, I_LED2



, and I_LED3



.

(1)

R_CS

Root-mean-square (RMS) value of the input current can

be calculated using the peak regulated current, I_LED3

Operation

,

and crest factor. Since the LED current waveform is

similar to the AC line voltage, the crest factor is close to

the crest factor of a sine wave, √2=1.414. But the actual

crest factor depends on the flattened time of the I_LED3

and LED configuration. With FL77905, the typical crest

factor is approximately 1.3. Thus, based on estimated

input power, P_IN, the R_CSresistor value can be

calculated as follows:

When the rectified AC line voltage, V_IN, is higher than

the forward voltage of the consecutive LED groups,

each LED group turns on automatically as the

corresponding current sink has enough voltage

headroom across it. Each current sink increases up to

the predefined current level and maintains that level

until the following channel’s current sink gets enough

voltage headroom across it.

AC Line

Voltage (V_IN

LED Current

(I_F)

0.96V_{AC .RMS}

)

R_CS

(2)

1.3 P

IN

I_LED3

I_LED2

V_F1''+V_F2'+V_F3

V_F1'+V_F2

The actual R_CSneeds to be adjusted with respect to the

LED configuration.

I_LED1

V_F1

LED Configuration

In the LED configuration, it is required to increase the

total LED forward voltage, V_Fto improve efficiency. For

example, compared to using 3 LEDs with V_Fof 80 V

(total V_F= 80 V x 3 channels = 240 V) for each LED

group, using 3 LEDs with V_Fof 90 V (total V_F= 90 V x 3

channels = 270 V) will improve the efficiency simply due

to the higher total V_F. Each LED channel can have

different V_F. For example, if a design is implemented

with 144 LEDs with V_Fof 3 V for 2-feet fluorescent lamp

replacement, the user can assign flexible number of

LEDs for LED channels such as 28s2p-34s2p-20s1p

(“s” stands for LEDs in series and “p” stands for LEDs in

parallel) or 27s2p-27s2p-36s1p.

t_D1t_D2

t_D3

t_D2t_D1

·

t_D1: Current is directed to LED1 pin through 1^stLED group.

t_D2: Current is directed to LED2 pin through 1^stand 2^ndLED groups.

t_D3: Current is directed to LED3 pin through 1^st, 2^nd, and 3^rdLED groups.

V_F1/V_F1'/V_F1'': Forward voltage at forward current of I_LED1/I_LED2/I_LED3in 1^stLED

group.

V_F2/V_F2': Forward voltage at forward current of I_LED2/I_LED3in 2^ndLED group.

V_F3: Forward voltage at forward current of I_LED3in 3^rdLED group.

·

Figure 8.

FL77905 Operation

When V_INreaches to the forward voltage across the 1st

LED group (V_F1) at forward current I_F= I_LED1, the current

drawn from the V_INis directed to the LED1 through the

1st LED group. In sequence, when V_INreaches forward

voltage across 1st and 2nd LED groups (V_F1'+V_F2) at I_F=

I_LED2, the current is directed to LED2 across 1st and 2nd

LED groups. Finally, when V_INreaches V_F1''+V_F2'+V_F3at

I_F=I_LED3, the LED current goes through 1st, 2nd, and 3rd

LED groups and sinks to the LED3.

Which needs to be considered is that V_Fof first LED

group should be higher than VIN-pin turn-on voltage,

which is 20 V. If the V_Fof the first LED group is

configured to be lower than VIN-pin turn-on voltage,

I_LED1will not have the correct regulation level when input

voltage, V_IN, is just exceeds the V_F.

Whenever the active channel (one that is sinking LED

current) is changed from one channel to the adjacent

channel with respect to the change in the V_IN, the new

active channel's current increases gradually while the

existing active channel's current decreases at the same

time. This smooth current transition reduces frequency

harmonic contents and improves power factor as well as

Electromagnetic Interference (EMI) characteristics.

A good starting point for choosing a LED configuration is

to have about 260 V~280 V of the total V_Ffor 220 V_AC

mains and 130 V~140 V of the total V_Ffor 120 V_AC

.

By fully utilizing available headroom, the FL77905 offers

maximum power, high efficiency, power factor and low

harmonic distortion. Typically, power factor is higher

FL77905 • Rev. 1.0

www.fairchildsemi.com

7

Internal Shunt Regulator Output, V_DD

Analog/PWM Dimming Function

The system implemented with FL77905 does not require

a bulk capacitor after bridge-rectification diodes. As a

result, the V_DD, which supplies biasing voltage for the

FL77905, has voltage ripple like the rectification voltage

after the bridge diodes as shown in Figure 9.

The FL77905 has its DIM pin always enabled. The DIM

pin is used for analog, 0 V to 10 V, or pulse width

modulation (PWM) dimming by applying a voltage signal

between 0 to 5 V or PWM signals with 5-V peaks to the

DIM pin.

Note that, if DIM pin is floating, there will be no LED

current, since DIM pin does not source voltage by itself.

If DIM-pin function is not required, use external circuit to

keep DIM-pin voltage at 5 V, or use the FL77904.

V_IN

IF1

VIN

1^stLED

}

V_DD

P1

S1

group

}

VIN

VDD

CS

LED1

LED2

2^ndLED

group

}

P2

P3

V_DDvalley

S2

S3

LED3

DIM

Figure 9.

V_DDRipple without C_VDD

GND

3^rdLED

group

C_VDD

The V_DDripple can be reduced by a bypassing

capacitor, C_VDD. If the C_VDDis not used, or its value is

small, the V_DDvoltage fluctuates and goes even down to

0 V. It makes the FL77905 reset, but the FL77905

automatically restarts every cycle when the AC line

voltage reaches a certain level. For a much stable

operation, to implement C_VDDis preferred. The

recommended C_VDDvalue is 1 µF with 50 V of voltage

rating.

R_CS

V_DIM

GND

* S1, S2, S3: Number of LEDs in series each LED group

* P1, P2, P3: Number of LEDs in parallel each LED group

Figure 10. Analog or PWM Dimming Application

The LED channel sink and total RMS current through

LEDs will be linearly adjusted with the V_DIMlevel as

shown in Figure 11.

Over-Temperature Protection (OTP)

The FL77905 is with over temperature protection (OTP)

inherently. When the driver's junction temperature ex-

ceeds a specified threshold temperature (T_J= 170°C),

the driver will shut down automatically and then recover

automatically once the temperature drops lower enough

than the internal threshold temperature. Without this

protection, the lifetime of the FL77905 can be reduced

and irreparable damage can occur when it operates

above its maximum junction temperature (150°C). Good

thermal management is required to achieve best

performance and long life span of the FL77905.

LED Channel Sink Current vs. VDIM

0.11

0.10

0.09

0.08

0.07

0.06

ILED1[A]

0.05

ILED2[A]

0.04

ILED3[A]

0.03

0.02

0.01

0.00

OTP also helps to screen out non-proper thermal

management during design-phase of a lighting fixture.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

VDIM[V]

Figure 11. LED Channel Sink Current vs. VDIM

(R_CS= 10 Ω)

FL77905 • Rev. 1.0

www.fairchildsemi.com

8

5.10

4.70

A

3.20

B

8

5

1.75

4.10

3.70

6.20

5.80

5.60

2.30

PIN #1

1

4

0.51

0.31

1.27

0.65

M

0.25

C B A

LAND PATTERN RECOMMENDATION

TOP VIEW

0.50

0.25

1.50

1.25

0.70

0.60

B

C

8°

0°

0.10

C

0.25

0.05

FRONT VIEW

0.25

0.10

SIDE VIEW

0.90

0.40

1.75 MAX

1

1.05

0.25

4

DETAIL B

SCALE 2:1

NOTES:

A. NO INDUSTRY STANDARD APPLIES TO THIS

PACKAGE

2.56

2.05

B. ALL DIMENSIONS ARE IN MILLIMETERS

C. DIMENSIONS DO NOT INCLUDE MOLD FLASH

OR BURRS

D. DRAWING FILENAME: MKT-M08Frev2

8

5

3.45

2.09

BOTTOM VIEW

ON Semiconductor and

are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries.

ON Semiconductor owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of ON Semiconductor’s product/patent

coverage may be accessed at www.onsemi.com/site/pdf/Patent−Marking.pdf. ON Semiconductor reserves the right to make changes without further notice to any products herein.

ON Semiconductor makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does ON Semiconductor assume any liability

arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.

Buyer is responsible for its products and applications using ON Semiconductor products, including compliance with all laws, regulations and safety requirements or standards,

regardless of any support or applications information provided by ON Semiconductor. “Typical” parameters which may be provided in ON Semiconductor data sheets and/or

specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer

application by customer’s technical experts. ON Semiconductor does not convey any license under its patent rights nor the rights of others. ON Semiconductor products are not

designed, intended, or authorized for use as a critical component in life support systems or any FDA Class 3 medical devices or medical devices with a same or similar classification

in a foreign jurisdiction or any devices intended for implantation in the human body. Should Buyer purchase or use ON Semiconductor products for any such unintended or unauthorized

application, Buyer shall indemnify and hold ON Semiconductor and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and

expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such

claim alleges that ON Semiconductor was negligent regarding the design or manufacture of the part. ON Semiconductor is an Equal Opportunity/Affirmative Action Employer. This

literature is subject to all applicable copyright laws and is not for resale in any manner.

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1


型号：	FL77905
厂家：	ONSEMI
描述：	Analog / PWM / Phase-cut Dimmable Compact LED Direct AC Driver
文件：	总11页 (文件大小：358K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

FL77905 [ONSEMI]

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FL7930C

FL7930CM