ISL97676 Datasheet, PDF (1/20 Pages) Intersil Corporation – 6-Channel LED Driver with Phase Shift Control

6-Channel LED Driver with Phase Shift Control
ISL97676
The ISL97676 is an LED driver that drives 6 channels of
LED current for TFT-Display. The ISL97676 drives 6
channels of LED to support 78 LEDs from 4.5V to 26V or
48 LEDs from a boost supply of 2.7V to 26V and a
separate 5V bias supply on the ISL97676 Vin pin.
The ISL97676 compensates for non-uniformity of the
forward voltage drops in the LED strings with its 6 voltage
controlled-current source channels. Its headroom control
monitors the highest LED forward voltage string for output
regulation, to minimize the voltage headroom and power
loss in the typical multi string operation.
Intersil offers two PWM Dimming modes: The ISL97676
digitizes the incoming PWM signal and provides 8-bit
dimming. The PWM frequency is set by a resistor
providing dimming frequency between 100Hz to 30kHz.
Secondly, direct PWM mode without phase shift, where the
dimming follows the input PWM signal.
The ISL97676 features channel phase shift control to
minimize the input, output ripple characteristics and load
transients as well as spreading the light output to help
eliminate or reduce the video and audio noise interference
from the backlight driver operation.
Features
• 6 Channels
• Channel Phase Shift PWM Dimming
• Direct PWM Dimming without Phase Shift
• 4.5V to 26V Input
• 45V Output Max
• Up to 30mA LED Current per Channel
• Drive up to 78 (3.2V/20mA each) LEDs
• Current Matching of ±1.5% from 1% ~ 100% Dimming
• Dynamic Headroom Control
• Protections
- String Open/Short Circuit, V_OUT Short Circuit
Overvoltage, and Over-temperature Protections
- Optional Master Fault Protection
• Selectable 600kHz or 1.2MHz Switching Frequency
• 20 Ld QFN 4mmx4mm Package
Applications
• Netbook Displays LED Backlighting
• Notebook Displays LED Backlighting
Typical Application Circuit
V_IN* = 4.5~26V
V_OUT = 45V*, 30mA PER STRING
ISL97676
17 FAULT
19 _VIN
1 _VDDIO
SW 16
OVP 14
5 _NC
PGND 15
2 EN
20 ^PWM
3 ^FSW/
PhaseShift
18 COMP
13
RFPWM//
DirectPWM
FB1 12
FB2 11
FB3 10
FB4 8
FB5 ⁷
4 _ISET
FB6 6
AGND 9
*For V_IN > 6V
March 12, 2010
FN7600.0
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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