Description

The AS3821 is a 12 channels precision LED for use in LCD-backlight panels.
Dynamic power feedback controls the external power supply to guarantee best efficiency.

Build in safety features include thermal shutdown as well as open and short LED detection.

The device is programmable via serial interface.

Key Features

• 12 Channel LED driver

• Output voltage only limited by external transistor

• Output current only limited by external transistor

• Linear current setting using 10-bit DAC

• Current accuracy ±0.5% @ VDAC=250mV

• Channel to Channel current accuracy ±0.2%

• BJT base current compensation

• Output slew rate programmable

• Digital current control with 12 independent PWM generators

• Free programmable 12 bit resolution

 ( period, high time and delay )

• PWM-generator clock

• Internal RC-oscillator

• External Clock

• PLL-synthesized clock from external signal

• H-Sync, V-Sync inputs to synchronize with TV

• Direct PWM mode

• Undervoltage detection ( open LED )

• Undervoltage auto-turnoff

• Short LED detection

• Temperature shutdown

• Register lock/unlock function

• Fault interrupt output

• 2 configurable supply regulation feedback outputs

• Enhanced digital feedback operation

• LDO (3.2V/20mA) for external MCU supply

• SPI interface

• 2kV ESD

• Package

LQFP44 10x10mm, 0.8m pitch

Applications

LED backlighting for LCD - TV sets and monitors

Block diagram for AS3821

Block diagram for AS3821