ISL97698

High Efficient 2-Channel White LED Driver for Smartphone Backlighting

Product Status: Mass Production

OVERVIEW

The ISL97698 is a highly integrated 2-channel LED driver for white LED (WLED) backlit TFT-LCD panels. The device is composed of a synchronous boost converter and two low-side current sinks that are capable of driving an output voltage up to 23.5V and 25mA LED current, per string. The IC operates from an input supply of 2.5V to 5.5V.

The driver features Dynamic Headroom Control that monitors the highest LED forward voltage string to determine the requested boost output voltage. With a controlled low 70mV headroom voltage and low 0.35mA IC supply current, the device provides very high efficiency.

The ISL97698 offers 8-bit linear or 11-bit logarithmic controlled analog output current, with dimming control from a PWM, SWIRE, or I2 C interface. Internally, the PWM duty cycle, SWIRE, and I2 C digital inputs are converted to a DC LED current. This analog dimming scheme provides high efficiency and eliminates audible noise and PWM dimming related EMI concerns. The ISL97698 also features Content Adaptive Backlight Control (CABC), which uses the product of the PWM and SWIRE, or PWM and I2 C, or SWIRE and I2 C inputs to determine the LED string current. The I2 C interface is also used for configuration settings and fault detection. The ISL97698 incorporates various protections including: open circuit, short circuit, and thermal shutdown.

The device is offered in a 1.39mmx 1.69mm, 3x4 array WLCSP package. It is specified for operation over the -40°C to +85°C ambient temperature range.

KEY FEATURES

  • High efficiency operation
  • Up to 91% with 2P4S configuration
  • Up to 90% with 2P6S configuration
  • Extremely low supply current (0.35mA)
  • Dynamic headroom control
  • Very low headroom voltage (70mV)
  • 20mm2 total solution PCB area
  • Only three external components required
  • Analog dimming control by PWM, SWIRE, or I2C
  • 8-bit Linear or 11-bit logarithmic analog output current control
  • Content Adaptive Backlight Control (CABC)
  • Input voltage from 2.5V to 5.5V
  • 23.5V maximum output voltage
  • Drives 50µA to 25mA LED strings
  • Open circuit and short circuit fault protection
  • 12 Bump, 0.4mm pitch chip scale package

BLOCK DIAGRAM

 Block Diagram

PARAMETRICS

Parameters
ISL97698
Basic Information
Production Status
Mass Production
# of Devices/ Channels
2
Total Current for DC/DC Lighting (mA)
50
Output Current Max/Channel (mA)
25
Output Voltage Max (V)
23.5
Brightness Control
Yes
Bus/Output Interface
I2C
Input Voltage Max (V)
5.5
Input Voltage Min (V)
2.5
Backlight for LCD Size (min) (in)
0
Backlight for LCD Size (max) (in)
5
Qualification Level
Standard
Peak Efficiency (%)
91
# of LEDs (max)
2-channel 23.5V 25mA LED Driver
Frequency
0.460 to 1.5 MHz
IQ (max)
350 µA
ISW (typ) (mA)
1100
Integrated Diode
No
Over Voltage Protection
Yes
Fault Switch
Yes
Topologies
Inductor Boost
Input Voltage Range (V)
2.5 to 5.5
Backlight for LCD Size
Up to 5
Temperature Range
-40 to +85

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