ISL6622ACRZ_技术文档

ISL6622A

®

Data Sheet

March 19, 2009

FN6601.2

VR11.1 Compatible Synchronous

Rectified Buck MOSFET Drivers

Features

• Dual MOSFET Drives for Synchronous Rectified Bridge

• Advanced Adaptive Zero Shoot-Through Protection

• 36V Internal Bootstrap Schottky Diode

The ISL6622A is a high frequency MOSFET driver designed

to drive upper and lower power N-Channel MOSFETs in a

synchronous rectified buck converter topology. The advanced

PWM protocol of ISL6622A is specifically designed to work

with Intersil VR11.1 controllers and combined with

N-Channel MOSFETs, form a complete core-voltage regulator

solution for advanced microprocessors. When ISL6622A

detects a PSI protocol sent by an Intersil VR11.1 controller, it

activates Diode Emulation (DE) operation; otherwise, it

operates in normal Continuous Conduction Mode (CCM)

PWM mode.

• Diode Emulation For Enhanced Light Load Efficiency

• Bootstrap Capacitor Overcharging Prevention

• Supports High Switching Frequency

- 3A Sinking Current Capability

- Fast Rise/Fall Times and Low Propagation Delays

• Advanced PWM Protocol (Patent Pending) to Support PSI

Mode, Diode Emulation, Three-State Operation

In the 8 Ld SOIC package, the ISL6622A drives the upper

gate to 12V while the lower get can be driven from 5V to 12V.

The 10 Ld DFN part allows for more flexibility. The upper gate

can be driven from 5V to 12V using the UVCC pin and the

lower gate can also be driven from 5V to 12V using the LVCC

pin. This provides the flexibility necessary to optimize

applications involving trade-offs between gate charge and

conduction losses.

• Pre-POR Overvoltage Protection for Start-up and

Shutdown

• VCC Undervoltage Protection

• Expandable Bottom Copper Pad for Enhanced Heat

Sinking

• Dual Flat No-Lead (DFN) Package

- Near Chip-Scale Package Footprint; Improves PCB

Efficiency and Thinner in Profile

To further enhance light load efficiency, the ISL6622A

enables diode emulation operation during PSI mode. This

allows Discontinuous Conduction Mode (DCM) by detecting

when the inductor current reaches zero and subsequently

turning off the low side MOSFET to prevent it from sinking

current.

• Pb-Free (RoHS Compliant)

Applications

• High Light Load Efficiency Voltage Regulators

• Core Regulators for Advanced Microprocessors

• High Current DC/DC Converters

An advanced adaptive shoot-through protection is integrated

to prevent both the upper and lower MOSFETs from

conducting simultaneously and to minimize dead time. The

ISL6622A has a 20kΩ integrated high-side gate-to-source

resistor to prevent self turn-on due to high input bus dV/dt.

This driver adds an overvoltage protection feature

operational while VCC is below its POR threshold; the

PHASE node is connected to the gate of the low side

MOSFET (LGATE) via a 10kΩ resistor limiting the output

voltage of the converter close to the gate threshold of the low

side MOSFET, dependent on the current being shunted,

which provides some protection to the load should the upper

MOSFET(s) become shorted.

• High Frequency and High Efficiency VRM and VRD

Related Literature

• Technical Brief TB363 “Guidelines for Handling and

Processing Moisture Sensitive Surface Mount Devices

(SMDs)”

• Technical Brief TB417 “Designing Stable Compensation

Networks for Single Phase Voltage Mode Buck

Regulators” for Power Train Design, Layout Guidelines,

and Feedback Compensation Design

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1

1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.

All other trademarks mentioned are the property of their respective owners.

ISL6622A

Ordering Information

PART NUMBER

(Note)

PART

MARKING

TEMP. RANGE

PACKAGE

(Pb-Free)

PKG.

DWG. #

(°C)

ISL6622ACBZ*

ISL6622ACRZ*

ISL6622AIBZ*

ISL6622AIRZ*

6622A CBZ

0 to +70

-40 to +85

8 Ld SOIC

M8.15

622A

10 Ld 3x3 DFN

8 Ld SOIC

L10.3x3

M8.15

6622A IBZ

22AI

10 Ld 3x3 DFN

L10.3x3

*Add “-T” suffix for tape and reel. Please refer to TB347 for details on reel specifications.

NOTE: These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100%

matte tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil

Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.

Pinouts

ISL6622A

(8 LD SOIC)

TOP VIEW

ISL6622A

(10 LD 3x3 DFN)

TOP VIEW

UGATE

BOOT

PWM

1

2

3

4

8

7

6

5

PHASE

VCC

1

2

3

4

5

10

9

UGATE

BOOT

NC

PHASE

VCC

8

LVCC

LGATE

PAD

UVCC

LVCC

LGATE

7

PWM

GND

6

Block Diagrams

ISL6622A

UVCC

BOOT

UGATE

20k

VCC

PHASE

LVCC

+5V

SHOOT-

PRE-POR OVP

FEATURES

THROUGH

LVCC

10k

PROTECTION

11.2k

9.6k

PWM

POR/

CONTROL

LOGIC

LGATE

GND

UVCC = VCC FOR SOIC

FN6601.2

March 19, 2009

2

ISL6622A

Typical Application Circuit

+5V

VIN

+12V

BOOT

LVCC

+5V

VCC

UGATE

PHASE

ISL6622A

DRIVER

LGATE

GND

PWM

+5V

COMP VCC

DAC

REF

FB

VDIFF

VSEN

PWM1

ISEN1-

ISEN1+

RGND

EN_VTT

BOOT

+12V

PVCC

VTT

VR_RDY

VID7

UGATE

PHASE

ISL6334

VCC

ISL6334

VID6

ISL6612

DRIVER

VID5

LGATE

GND

VID4

PWM

PWM2

ISEN2-

VID3

VID2

VID1

ISEN2+

VID0

PSI

+5V

BOOT

+12V

PVCC

PWM3

ISEN3-

VR_FAN

VR_HOT

µP

LOAD

UGATE

PHASE

ISEN3+

VIN

VCC

ISL6612

DRIVER

EN_PWR

LGATE

GND

PWM

GND

PWM4

ISEN4-

ISEN4+

IMON

TCOMP

TM

+5V

BOOT

OFS

FS

SS

+12V

PVCC

+5V

UGATE

PHASE

VCC

ISL6612

DRIVER

NTC

LGATE

GND

PWM

FN6601.2

March 19, 2009

3

ISL6622A

Absolute Maximum Ratings

Thermal Information

Supply Voltage (VCC, UVCC, LVCC) . . . . . . . . . . . . . . . . . . . . .15V

Thermal Resistance

θ

(°C/W)

θ

(°C/W)

JC

JA

BOOT Voltage (V ). . . . . . . . . . . . . . . . . . . . . . . . . . . .36V

BOOT-GND

) . . . . . . . . . . . . . . . . . . . . . .GND - 0.3V to 7V

SOIC Package (Note 1) . . . . . . . . . . . .

DFN Package (Notes 2, 3). . . . . . . . . .

Maximum Storage Temperature Range. . . . . . . . . .-65°C to +150°C

Pb-free reflow profile . . . . . . . . . . . . . . . . . . . . . . . . . .see link below

http://www.intersil.com/pbfree/Pb-FreeReflow.asp

100

48

N/A

7

Input Voltage (V

PWM

UGATE. . . . . . . . . . . . . . . . . . . V

- 0.3V

to V

+ 0.3V

PHASE

DC

BOOT

V

- 3.5V (<100ns Pulse Width, 2µJ) to V

PHASE

LGATE . . . . . . . . . . . . . . . . . . . . . . .GND - 0.3V

to V

DC

GND - 5V (<100ns Pulse Width, 2µJ) to V

LVCC

PHASE. . . . . . . . . . . . . . . . . . . . . . . . . . . . GND - 0.3V

to 15V

DC

Recommended Operating Conditions

GND - 8V (<400ns, 20µJ) to 30V (<200ns, V

< 36V)

BOOT-GND

Ambient Temperature Range

ISL6622AIBZ, ISL6622AIRZ . . . . . . . . . . . . . . . . .-40°C to +85°C

ISL6622ACBZ, ISL6622ACRZ. . . . . . . . . . . . . . . . . 0°C to +70°C

Maximum Operating Junction Temperature. . . . . . . . . . . . . +125°C

Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8V to 13.2V

Supply Voltage Range, UVCC . . . . . . . . . . . . . . . . . 4.75V to 13.2V

Supply Voltage Range, LVCC . . . . . . . . . . . . . . . . . . 4.75V to 13.2V

CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product reliability and

result in failures not covered by warranty.

NOTES:

1. θ is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tech Brief TB379 for details.

JA

2. θ is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See

JA

Tech Brief TB379.

3. For θ , the “case temp” location is the center of the exposed metal pad on the package underside.

JC

4. Limits should be considered typical and are not production tested.

Electrical Specifications Recommended Operating Conditions. Parameters with MIN and/or MAX limits are 100% tested at +25°C,

unless otherwise specified. Temperature limits established by characterization and are not

production tested.

PARAMETER

VCC SUPPLY CURRENT (Note 4)

No Load Switching Supply Current

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNITS

I

ISL6622ACBZ and ISL6622AIBZ,

-

7

3.5

4

-

mA

VCC

f

= 300kHz, V

= 12V

VCC

PWM

I

LVCC

I

ISL6622ACRZ and ISL6622AIRZ,

= 300kHz, V = 12V

VCC

f

PWM

VCC

I

3.5

3

LVCC

I

UVCC

Standby Supply Current

I

ISL6622ACBZ and ISL6622AIBZ,

PWM Transition from 0V to 2.5V

5.5

0.15

5

VCC

I

LVCC

I

ISL6622ACRZ and ISL6622AIRZ,

PWM Transition from 0V to 2.5V

VCC

I

0.15

0.5

LVCC

UVCC

I

POWER-ON RESET

VCC Rising Threshold

6.25

4.8

6.45

5.0

4.4

3.4

6.70

5.25

4.55

3.55

V

VCC Falling Threshold

LVCC Rising Threshold

4.25

3.3

LVCC Falling Threshold

PWM INPUT (See “TIMING DIAGRAM” on page 6)

Input Current (Note 4)

I

V

= 5V

= 0V

-

500

-430

3.4

-

µA

V

PWM

PWM Rising Threshold (Note 4)

VCC = 12V

PWM Falling Threshold (Note 4)

1.6

V

Three-State Lower Gate Falling Threshold (Note 4)

Three-State Lower Gate Rising Threshold (Note 4)

1.6

V

1.1

V

FN6601.2

March 19, 2009

4

ISL6622A

Electrical Specifications Recommended Operating Conditions. Parameters with MIN and/or MAX limits are 100% tested at +25°C,

unless otherwise specified. Temperature limits established by characterization and are not

production tested. (Continued)

PARAMETER

Three-State Upper Gate Rising Threshold (Note 4)

Three-State Upper Gate Falling Threshold (Note 4)

UGATE Rise Time (Note 4)

SYMBOL

TEST CONDITIONS

VCC = 12V

MIN

TYP

3.2

2.8

26

MAX

UNITS

V

-

V

t

V

= 12V, 3nF Load, 10% to 90%

= 12V, 3nF Load, 90% to 10%

= 12V, 3nF Load, Adaptive

= 12V, 3nF Load

-

ns

RU

VCC

LGATE Rise Time (Note 4)

t

-

18

-

RL

FU

UGATE Fall Time (Note 4)

-

18

-

LGATE Fall Time (Note 4)

t

-

12

-

FL

UGATE Turn-On Propagation Delay (Note 4)

LGATE Turn-On Propagation Delay (Note 4)

UGATE Turn-Off Propagation Delay (Note 4)

LGATE Turn-Off Propagation Delay (Note 4)

LG/UG Three-State Propagation Delay (Note 4)

Diode Braking Holdoff Time (Note 4)

Minimum LGATE On-Time at Diode Emulation

OUTPUT (Note 4)

t

-

20

-

PDHU

t

-

10

-

PDHL

PDLU

t

-

10

-

t

= 12V, 3nF Load

-

10

-

PDLL

PDTS

t

= 12V, 3nF Load

-

10

-

t

= 12V

60

UG_OFF_DB

t

= 12V

230

330

450

LG_ON_DM

U_SOURCE

Upper Drive Source Current

I

V

= 12V, 3nF Load

-

1.25

2

-

A

Ω

A

Ω

A

Ω

A

Ω

VCC

Upper Drive Source Impedance

Upper Drive Sink Current

R

20mA Source Current

U_SOURCE

I

V

= 12V, 3nF Load

2

U_SINK

VCC

20mA Sink Current

V = 12V, 3nF Load

Upper Drive Sink Impedance

R

1.35

2

U_SINK

Lower Drive Source Current

I

L_SOURCE

VCC

20mA Source Current

Lower Drive Source Impedance

Lower Drive Sink Current

R

1.35

3

L_SOURCE

I

V

= 12V, 3nF Load

L_SINK

VCC

Lower Drive Sink Impedance

R

20mA Sink Current

0.9

L_SINK

Functional Pin Descriptions

PACKAGE PIN #

SOIC

DFN

SYMBOL

FUNCTION

1

2

1

2

UGATE Upper gate drive output. Connect to gate of high-side power N-Channel MOSFET.

BOOT

Floating bootstrap supply pin for the upper gate drive. Connect the bootstrap capacitor between this pin and the

PHASE pin. The bootstrap capacitor provides the charge to turn on the upper MOSFET. See “Internal Bootstrap

Device” on page 7 for guidance in choosing the capacitor value.

-

3

4

NC

No Connect

3

PWM

The PWM signal is the control input for the driver. The PWM signal can enter three distinct states during operation;

see “Description” on page 6 for further details. Connect this pin to the PWM output of the controller.

4

5

6

5

6

7

GND

Bias and reference ground. All signals are referenced to this node. It is also the power-ground return of the driver.

LGATE Lower gate drive output. Connect to gate of the low-side power N-Channel MOSFET.

LVCC

UVCC

VCC

This pin supplies power to the lower gate drive. Its operating range is +5V to +12V. Place a high quality low ESR

ceramic capacitor from this pin to GND.

-

7

8

-

8

9

This pin supplies power to the upper gate drive. Its operating range is +5V to +12V. Place a high quality low ESR

ceramic capacitor from this pin to GND.

Connect this pin to 12V bias supply. This pin supplies power to the upper gate in the SOIC. Place a high quality

low ESR ceramic capacitor from this pin to GND.

10

11

PHASE Connect this pin to the SOURCE of the upper MOSFET and the DRAIN of the lower MOSFET. This pin provides

a return path for the upper gate drive.

PAD

Connect this pad to the power ground plane (GND) via thermally enhanced connection.

FN6601.2

March 19, 2009

5

ISL6622A

1.5V < PWM < 3.2V

1.0V< PWM < 2.6V

UG_OFF_DB

PWM

t

PDLU

PDHU

t

PDTS

t

PDTS

t

FU

UGATE

LGATE

t

RU

t

FL

RL

t

TSSHD

PDLL

t

PDHL

FIGURE 1. TIMING DIAGRAM

shoot-through caused by the self turn-on of the lower

MOSFET due to high dV/dt of the switching node.

Description

Operation and Adaptive Shoot-through Protection

Advanced PWM Protocol (Patent Pending)

Designed for high speed switching, the ISL6622A MOSFET

driver controls both high-side and low-side N-Channel FETs

from one externally provided PWM signal.

The advanced PWM protocol of ISL6622A is specifically

designed to work with Intersil VR11.1 controllers. When

ISL6622A detects a PSI protocol sent by an Intersil VR11.1

controller, it turns on diode emulation operation; otherwise, it

remains in normal CCM PWM mode.

A rising transition on PWM initiates the turn-off of the lower

MOSFET (see Figure 1). After a short propagation delay

[t

], the lower gate begins to fall. Typical fall time [t ] is

PDLL

FL

Another unique feature of ISL6622A and other Intersil

drivers is the addition of a three-state shutdown window to

the PWM input. If the PWM signal enters and remains within

the shutdown window for a set holdoff time, the driver

outputs are disabled and both MOSFET gates are pulled and

held low. The shutdown state is removed when the PWM

signal moves outside the shutdown window. Otherwise, the

PWM rising and falling thresholds outlined in the “Electrical

Specifications” on page 4 determine when the lower and

upper gates are enabled. This feature helps prevent a

negative transient on the output voltage when the output is

shut down, eliminating the Schottky diode that is used in

some systems for protecting the load from reversed output

voltage events.

provided in the “Electrical Specifications” on page 5. Following

a 25ns blanking period, adaptive shoot-through circuitry

monitors the LGATE voltage and turns on the upper gate

following a short delay time [t

] after the LGATE voltage

drops below ~1.75V. The upper gate drive then begins to rise

PDHU

[t ] and the upper MOSFET turns on.

RU

A falling transition on PWM indicates the turn-off of the upper

MOSFET and the turn-on of the lower MOSFET. A short

propagation delay [t

] is encountered before the upper

PDLU

gate begins to fall [t ]. The adaptive shoot-through circuitry

FU

monitors the UGATE-PHASE voltage and turns on the lower

MOSFET a short delay time [t

] after the upper

PDHL

MOSFET’s PHASE voltage drops below +0.8V or 40ns after

the upper MOSFET’s gate voltage [UGATE-PHASE] drops

Note that the LGATE will not turn off until the diode

emulation minimum LGATE ON-time of 350ns is expired for

a PWM low to tri-level (2.5V) transition.

below ~1.75V. The lower gate then rises [t ], turning on the

lower MOSFET. These methods prevent both the lower and

upper MOSFETs from conducting simultaneously

RL

(shoot-through), while adapting the dead-time to the gate

charge characteristics of the MOSFETs being used.

Power-On Reset (POR) Function

During initial start-up, the VCC voltage rise is monitored.

Once the rising VCC voltage exceeds rising POR threshold,

operation of the driver is enabled and the PWM input signal

takes control of the gate drives. If VCC drops below the

falling threshold, operation of the driver is disabled.

This driver is optimized for voltage regulators with large step

down ratio. The lower MOSFET is usually sized larger

compared to the upper MOSFET because the lower MOSFET

conducts for a longer time during a switching period. The

lower gate driver is therefore sized much larger to meet this

application requirement. The 0.8Ω ON-resistance and 3A sink

current capability enable the lower gate driver to absorb the

current injected into the lower gate through the drain-to-gate

capacitor of the lower MOSFET and help prevent

Pre-POR Overvoltage Protection

While VCC is below its POR level, the upper gate is held low

and LGATE is connected to the PHASE pin via an internal

10kΩ (typically) resistor. By connecting the PHASE node to the

gate of the low side MOSFET, the driver offers some passive

FN6601.2

March 19, 2009

6

ISL6622A

protection to the load if the upper MOSFET(s) is or becomes

shorted. If the PHASE node goes higher than the gate

threshold of the lower MOSFET, it results in the progressive

turn-on of the device and the effective clamping of the PHASE

node’s rise. The actual PHASE node clamping level depends

on the lower MOSFET’s electrical characteristics, as well as the

characteristics of the input supply and the path connecting it to

the respective PHASE node.

upper gate drive is fixed to VCC [+12V] in the SOIC, but the

lower drive rail can be driven from 5V to 12V using the LVCC

pin. In the DFN package, a separate UVCC pin is available

for the upper gate drive voltage to be driven from 5V to 12V

for efficiency optimization, while the lower gate can be driven

independently using the LVCC pin from 5V to 12V.

Diode Emulation

Diode emulation allows for higher converter efficiency under

light-load situations. With diode emulation active, the

ISL6622A detects the zero current crossing of the output

inductor and turns off LGATE. This prevents the low side

MOSFET from sinking current and ensures that

Internal Bootstrap Device

The ISL6622A features an internal bootstrap Schottky diode.

Simply adding an external capacitor across the BOOT and

PHASE pins completes the bootstrap circuit. The bootstrap

function is also designed to prevent the bootstrap capacitor

from overcharging due to the large negative swing at the

trailing-edge of the PHASE node. This reduces voltage

stress on the BOOT to PHASE pins.

discontinuous conduction mode (DCM) is achieved. The

LGATE has a minimum on-time of 350ns in DCM mode.

Power Dissipation

Package power dissipation is mainly a function of the

1.6

1.4

1.2

1.0

0.8

0.6

switching frequency (F ), the output drive impedance, the

SW

external gate resistance, and the selected MOSFET’s internal

gate resistance and total gate charge. Calculating the power

dissipation in the driver for a desired application is critical to

ensure safe operation. Exceeding the maximum allowable

power dissipation level may push the IC beyond the maximum

recommended operating junction temperature. The DFN

package is more suitable for high frequency applications. See

“Layout Considerations” on page 8 for thermal transfer

improvement suggestions. When designing the driver into an

application, it is recommended that the following calculation is

used to ensure safe operation at the desired frequency for the

selected MOSFETs. The total gate drive power losses due to

the gate charge of MOSFETs and the driver’s internal circuitry

and their corresponding average driver current can be

estimated with Equations 2 and 3, respectively:

Q

= 100nC

GATE

0.4

50nC

0.2

0.0

20nC

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

ΔV (V)

BOOT_CAP

FIGURE 2. BOOTSTRAP CAPACITANCE vs BOOT RIPPLE

VOLTAGE

(EQ. 2)

P

= P

+ P

+ I • VCC

Q

Qg_TOT

Qg_Q1

Qg_Q2

2

Q

• UVCC

G1

The bootstrap capacitor must have a maximum voltage

rating well above the maximum voltage intended for UVCC.

Its minimum capacitance value can be chosen from

Equation 1.

---------------------------------------

P

=

• F

• N

Qg_Q1

SW

Q1

V

GS1

2

Q

• LVCC

G2

--------------------------------------

P

=

• F

Qg_Q2

SW

Q2

V

GS2

Q

GATE

-------------------------------------

C

≥

BOOT_CAP

ΔV

BOOT_CAP

(EQ. 1)

Q

• UVCC • N

Q

• LVCC • N

G2 Q2

⎛

⎜

⎝

⎞

⎟

⎠

G1

Q1

----------------------------------------------------- ----------------------------------------------------

I

=

+

• F

+ I

DR

SW

Q

V

GS2

GS1

Q

• UVCC

G1

-----------------------------------

Q

=

• N

Q1

(EQ. 3)

GATE

V

GS1

where the gate charge (Q and Q ) is defined at a

G1

G2

where Q is the amount of gate charge per upper MOSFET

G1

particular gate to source voltage (V

and V

) in the

GS1

GS2

at V

gate-source voltage and N is the number of

GS1

control MOSFETs. The ΔV

Q1

corresponding MOSFET data sheet; I is the driver’s total

Q

term is defined as the

BOOT_CAP

quiescent current with no load at both drive outputs; N

and N are number of upper and lower MOSFETs,

Q2

respectively; UVCC and LVCC are the drive voltages for

Q1

allowable droop in the rail of the upper gate drive. Select

results are exemplified in Figure 2.

both upper and lower FETs, respectively. The I VCC

product is the quiescent power of the driver without

capacitive load.

Q*

Gate Drive Voltage Versatility

The ISL6622A provides the user flexibility in choosing the

gate drive voltage for efficiency optimization. The ISL6622A

FN6601.2

March 19, 2009

7

ISL6622A

The total gate drive power losses are dissipated among the

resistive components along the transition path, as outlined in

Equation 4. The drive resistance dissipates a portion of the

total gate drive power losses, the rest will be dissipated by the

external gate resistors (R and R ) and the internal gate

• Minimize trace inductance, especially low-impedance

lines: all power traces (UGATE, PHASE, LGATE, GND,

LVCC) should be short and wide, as much as possible.

• Minimize the inductance of the PHASE node: ideally, the

source of the upper and the drain of the lower MOSFET

should be as close as thermally allowable.

G1

G2

resistors (R

and R ) of MOSFETs. Figures 3 and 4 show

GI1

GI2

the typical upper and lower gate drives turn-on current path.

• Minimize the input current loop: connect the source of the

lower MOSFET to ground as close to the transistor pin as

feasible; input capacitors (especially ceramic decoupling)

should be placed as close to the drain of upper and source

of lower MOSFETs as possible.

P

= P

+ P

+ I • VCC

(EQ. 4)

DR

DR_UP

DR_LOW

Q

R

P

Qg_Q1

⎛

⎞

HI1

LO1

-------------------------------------- --------------------------------------- ---------------------

P

=

+

•

⎜

⎝

⎟

DR_UP

R

+ R

R

+ R

EXT1

2

⎠

HI1

EXT1

LO1

In addition, for improved heat dissipation, place copper

underneath the IC whether it has an exposed pad or not. The

copper area can be extended beyond the bottom area of the

IC and/or connected to buried power ground plane(s) with

thermal vias. This combination of vias for vertical heat

escape, extended surface copper islands, and buried planes

combine to allow the IC and the power switches to achieve

their full thermal potential.

R

P

Qg_Q2

⎛

⎜

⎝

⎞

HI2

LO2

-------------------------------------- --------------------------------------- ---------------------

P

R

=

+

•

⎟

DR_LOW

R

+ R

R

+ R

EXT2

2

⎠

HI2

EXT2

LO2

R

GI1

GI2

-------------

= R

+

R

= R +

G2

EXT1

G1

EXT2

N

Q1

Q2

UVCC

BOOT

D

Upper MOSFET Self Turn-On Effects At Startup

C

GD

R

Should the driver have insufficient bias voltage applied, its

outputs are floating. If the input bus is energized at a high

dV/dt rate while the driver outputs are floating, due to

HI1

G

C

DS

R

LO1

R

GI1

C

G1

GS

self-coupling via the internal C

of the MOSFET, the gate of

GD

Q1

the upper MOSFET could momentarily rise up to a level

greater than the threshold voltage of the device, potentially

turning on the upper switch. Therefore, if such a situation

could conceivably be encountered, it is a common practice to

S

PHASE

FIGURE 3. TYPICAL UPPER-GATE DRIVE TURN-ON PATH

place a resistor (R

) across the gate and source of the

UGPH

LVCC

upper MOSFET to suppress the Miller coupling effect. The

value of the resistor depends mainly on the input voltage’s

D

rate of rise, the C /C

ratio, as well as the gate-source

GD GS

C

GD

threshold of the upper MOSFET. A higher dV/dt, a lower

/C ratio, and a lower gate-source threshold upper FET

R

HI2

G

C

DS GS

DS

will require a smaller resistor to diminish the effect of the

internal capacitive coupling. For most applications, the

integrated 20kΩ resistor is sufficient, not affecting normal

performance and efficiency.

R

LO2

R

GI2

C

G2

GS

Q2

S

The coupling effect can be roughly estimated with

Equation 5, which assumes a fixed linear input ramp and

neglects the clamping effect of the body diode of the upper

drive and the bootstrap capacitor. Other parasitic

components such as lead inductances and PCB

capacitances, are also not taken into account. Figure 5

provides a visual reference for this phenomenon and its

potential solution.

FIGURE 4. TYPICAL LOWER-GATE DRIVE TURN-ON PATH

Application Information

Layout Considerations

During switching of the devices, the parasitic inductances of

the PCB and the power devices’ packaging (both upper and

lower MOSFETs) leads to ringing, possibly in excess of the

absolute maximum rating of the devices. Careful layout can

help minimize such unwanted stress. The following advice is

meant to lead to an optimized layout:

–V

DS

⎛

⎜

⎝

⎞

⎟

⎠

---------------------------------

dV

-------

⋅ R ⋅ C

dV

dt

iss

dt

-------

V

=

⋅ R ⋅ C

1 – e

(EQ. 5)

GS_MILLER

rss

• Keep decoupling loops (LVCC-GND and BOOT-PHASE)

as short as possible.

C

= C

+ C

C

= C

R = R

+ R

GI

iss

GD

GS

rss

GD

UGPH

FN6601.2

March 19, 2009

8

ISL6622A

Gate Drive Voltage Options

UVCC

VIN

BOOT

Intersil provides various gate drive voltage options in

ISL6622 product family, as shown in Table 2.

D

C

BOOT

C

UGATE

GD

The ISL6622 can drop the low-side MOSFET’s gate drive

voltage when operating in DEM, while the high-side FET’s

gate drive voltage of the DFN package can be connected to

VCC or LVCC.

C

DU

DL

DS

G

R

GI

C

Q

UPPER

GS

The ISL6622A allows the low-side MOSFET(s) to operate

from an externally-provided rail as low as 5V, eliminating the

LDO losses, while the high-side MOSFET’s gate drive

voltage of the DFN package can be connected to VCC or

LVCC.

S

PHASE

FIGURE 5. GATE-TO-SOURCE RESISTOR TO REDUCE

UPPER MOSFET MILLER COUPLING

The ISL6622B sets the low-side MOSFET’s gate drive

voltage at a fixed, programmable LDO level, while the high-

side FETs’ gate drive voltage of the DFN package can be

connected to VCC or LVCC.

TABLE 1. ISL6622 FAMILY OPTIONS

LVCC

POWER RAILS

PSI = LOW

5.75V

PSI = HIGH

11.2V

UVCC

VCC

ISL6622

SOIC

DFN

SOIC

DFN

SOIC

DFN

Operating Voltage Ranges from 6.8V to 13.2V

Programmable

11.2V

Own Rail

VCC

ISL6622A

ISL6622B

Own Rail

VCC

5.75V

Programmable

Own Rail

FN6601.2

March 19, 2009

9

ISL6622A

Dual Flat No-Lead Plastic Package (DFN)

2X

L10.3x3

0.15

C A

2X

10 LEAD DUAL FLAT NO-LEAD PLASTIC PACKAGE

D

A

MILLIMETERS

0.15 C

B

SYMBOL

MIN

0.80

NOMINAL

0.90

MAX

1.00

NOTES

A

A1

A3

b

-

0.18

1.95

1.55

-

0.05

-

E

0.20 REF

0.23

-

6

0.28

2.05

1.65

5,8

INDEX

AREA

D

3.00 BSC

2.00

-

D2

E

7,8

TOP VIEW

B

A

3.00 BSC

1.60

-

E2

e

7,8

0.10 C

0.08 C

0.50 BSC

-

k

0.25

0.30

-

L

0.35

0.40

8

SIDE VIEW

C

A3

SEATING

PLANE

N

10

2

Nd

5

3

7

8

Rev. 3 6/04

D2

NOTES:

(DATUM B)

1. Dimensioning and tolerancing conform to ASME Y14.5-1994.

2. N is the number of terminals.

D2/2

1

2

6

3. Nd refers to the number of terminals on D.

INDEX

AREA

k

NX

E2

4. All dimensions are in millimeters. Angles are in degrees.

(DATUM A)

5. Dimension b applies to the metallized terminal and is measured

between 0.15mm and 0.30mm from the terminal tip.

E2/2

6. The configuration of the pin #1 identifier is optional, but must be

located within the zone indicated. The pin #1 identifier may be

either a mold or mark feature.

NX L

8

N

N-1

e

7. Dimensions D2 and E2 are for the exposed pads which provide

improved electrical and thermal performance.

NX b

5

8. Nominal dimensions are provided to assist with PCB Land

Pattern Design efforts, see Intersil Technical Brief TB389.

(Nd-1)Xe

0.10 M C A B

REF.

BOTTOM VIEW

C

L

0.415

NX (b)

(A1)

L

0.200

NX b

NX L

5

e

SECTION "C-C"

TERMINAL TIP

FOR ODD TERMINAL/SIDE

C C

C

FN6601.2

March 19, 2009

10

ISL6622A

Small Outline Plastic Packages (SOIC)

M8.15 (JEDEC MS-012-AA ISSUE C)

8 LEAD NARROW BODY SMALL OUTLINE PLASTIC PACKAGE

N

INDEX

AREA

0.25(0.010)

M

B M

H

INCHES MILLIMETERS

E

SYMBOL

MIN

MAX

MIN

1.35

0.10

0.33

0.19

4.80

3.80

MAX

1.75

0.25

0.51

0.25

5.00

4.00

NOTES

-B-

A

A1

B

C

D

E

e

0.0532

0.0040

0.013

0.0688

0.0098

0.020

-

1

2

3

L

9

SEATING PLANE

A

0.0075

0.1890

0.1497

0.0098

0.1968

0.1574

-

-A-

3

h x 45°

D

4

-C-

0.050 BSC

1.27 BSC

-

α

H

h

0.2284

0.0099

0.016

0.2440

0.0196

0.050

5.80

0.25

0.40

6.20

0.50

1.27

-

e

A1

C

5

B

0.10(0.004)

L

6

0.25(0.010) M

C

A M B S

N

α

8

7

NOTES:

0°

8°

0°

8°

-

1. Symbols are defined in the “MO Series Symbol List” in Section 2.2 of

Publication Number 95.

Rev. 1 6/05

2. Dimensioning and tolerancing per ANSI Y14.5M-1982.

3. Dimension “D” does not include mold flash, protrusions or gate burrs.

Mold flash, protrusion and gate burrs shall not exceed 0.15mm (0.006

inch) per side.

4. Dimension “E” does not include interlead flash or protrusions. Inter-

lead flash and protrusions shall not exceed 0.25mm (0.010 inch) per

side.

5. The chamfer on the body is optional. If it is not present, a visual index

feature must be located within the crosshatched area.

6. “L” is the length of terminal for soldering to a substrate.

7. “N” is the number of terminal positions.

8. Terminal numbers are shown for reference only.

9. The lead width “B”, as measured 0.36mm (0.014 inch) or greater

above the seating plane, shall not exceed a maximum value of

0.61mm (0.024 inch).

10. Controlling dimension: MILLIMETER. Converted inch dimensions

are not necessarily exact.

All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.

Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality

Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without

notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and

reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result

from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.

For information regarding Intersil Corporation and its products, see www.intersil.com

FN6601.2

March 19, 2009

11


型号：	ISL6622ACRZ
厂家：	Intersil
描述：	VR11.1 Compatible Synchronous Rectified Buck MOSFET Drivers VR11.1兼容同步整流降压MOSFET驱动器驱动器
文件：	总11页 (文件大小：238K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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