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Compact 2-3-4-Ch LED Drivers with Phase Shift Control

ISL97682, ISL97683, ISL97684

The ISL97682, ISL97683, ISL97684 are Intersil’s highly

integrated 2-3-4-channels LED drivers that are suitable for

medium size TFT-LCD backlights. These parts can drive multiple

channels of LEDs from inputs as low as 4V to outputs of up to

45V. They can also operate from inputs as low as 3V to outputs of

up to 26.5V in bootstrap configuration (see Figure 26 for 3V

operation).

The ISL97682, ISL97683, ISL97684 feature optional channels

phase shift control. This feature is used to minimize the input,

output ripple characteristics and load transient, which help

eliminate or reduce the video and audio noise interference from

the backlight driver operation.

The ISL97682, ISL97683, ISL97684 offer 8-bit PWM dimming for

systems that need frequency tuning flexibility. With the unique

adaptive boost switching architecture, the ISL97682, ISL97683,

ISL97684 also offer Direct PWM dimming with output, which

follows input and achieves linearity as low as 0.009% at 200Hz

or 1.35% at 30kHz.

The drivers incorporate dynamic headroom control that monitors

the highest LED forward voltage string and uses its feedback signal

for the minimum output regulation. The ISL97682, ISL97683,

ISL97684 incorporates extensive fault protection functions including

string open and short circuit detections, OVP, and OTP. The switching

frequency can be selected at either 600kHz or 1.0MHz in PFM or

PWM mode. These parts are available in the thin and compact

16 Ld 3mmx3mm TQFN package and operate in ambient

temperature from -40°C to +85°C.

Features

• ISL97682 - 2 x 100mA Channels

• ISL97683 - 3 x 50mA Channels

• ISL97684 - 4 x 50mA Channels

• PWM Dimming Linearity

- PWM Dimming with Adjustable Dimming Frequency with

Duty Cycle Linear from 0.4% to 100% <30kHz

- Direct PWM Dimming with Duty Cycle Linear from 0.009%

to 100% at 200Hz

• Current Matching of 0.7% typical from 1%~100% Dimming

• Selectable 600kHz or 1MHz Switching Frequency in PWM/PFM

Mode

• Dynamic Headroom Control

•Fault Protection

-String Open/Short Circuit Protections, OVP, OTP

• Thin and Compact TQFN-16 3mmx3mm Package

Applications

• Tablet to Notebook PC Displays LED Backlighting

• PMP LED Backlighting

FIGURE 1A. DIRECT PWM DIMMING

FIGURE 1B. PWM DIMMING WITH DIMMING FREQUENCY

FIGURE 1. ISL97684 TYPICAL APPLICATION DIAGRAMS

VDC

VIN

OVP

45V, 4 x 50mA*

CH1

CH4

CH2

CH3

11

16

15

14

13

12

7

LX 9

ISL97684

L1

10µH

D1

Co

4.7µF

Ci

10µF

1µF

10

PGND

0.1µF

AGND

1

RSET

PWMI

COMP

5

3

8

2

6

FSW

4

FPWM/DIRECTPWM

EN

GOOD LEDS MATCHING

33pF

10kΩ

8.2nF

VDC

VIN

OVP

45V, 4 x 50mA*

CH1

CH4

CH2

CH3

11

16

15

14

13

12

7

LX 9

ISL97684

L1

10µH

D1

Co

4.7µF

Ci

10µF

1µF

10

PGND

0.1µF

AGND

1

RSET

PWMI

COMP

5

3

8

2

6

FSW

4

FPWM/DIRECTPWM

EN

GOOD LEDS MATCHING

33pF

10kΩ

8.2nF

May 16, 2012

FN7689.1

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

1-888-INTERSIL or 1-888-468-3774

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