AS3694 Backlighting IC

Description

The AS3694 is a 12 channels high precision LED driver with built-in PWM generators for building backlight panels in LCD-TV-sets. 3 DCDC Step Up controllers can be used to build the power supplies for red, green and blue LED strings.

External clock and synchronizing inputs allow the synchronization of the LCD backlight with the TV picture. Local dimming and scan dimming is supported by 12 independent PWM generators with programmable delay, period and duty cycle.

Three free configurable dynamic power feedback circuits make the device usable for white LED as well as RGB backlights. Built-in safety features include thermal shutdown as well as open and short LED detection. All circuit parameters are programmable via I²C or SPI interface.

Key Features

• 12 independent LED channels
• Output current 70mA
• Output voltage up to 50V
• Absolute current accuracy ±0.5%
• Output slew rate limited to reduce EMI
• Current programmable with external resistor
• 12 independent PWM generators with 12-bit resolution
• H-Sync, F-Sync inputs to synchronize with TV-set
• Three independent power feedback for R,G,B supply regulation
• Built-in 5V shunt regulator
• I²C or SPI interface with 6-bit address
• Fault interrupt output
• Open LED detection
• Short LED detection
• Temperature shutdown
• 3 DCDC Step Up controller
  • Current mode
  • Efficiency > 90%
  • Input voltage range 15V to 50V
  • Output voltage up to 50V / 200mA
• Package epTQFP64

Applications

LED Backlighting for LCD – TV Sets and Monitors

Block Diagram