Two LED driver ICs from Austriamicrosystems are the first in a family of 3rd generation drivers that minimise energy consumption. The 16-channel AS3820 and the 12-channel AS3821 meet the needs of the most common architectures of direct and edge-lit LED TVs. Both feature ±0.2% channel-to-channel accuracy. This is the highest accuracy available, says the company, to guarantee light uniformity and picture quality. The ICs can drive external power MOSFETs or take advantage of the base current error compensation to drive less expensive, low beta, bipolar transistors. The ICs use a power supply control technique to provide fast response time. Direct control of the output voltage of any standard DC/DC converter is especially useful for designing 3D TVs. The ICs also introduce regulation which has no exposure to the high-voltage LED supply since no connection to the external transistor drain pin is required. The devices are programmable via an SPI port. Safety features include thermal shutdown and open and short LED detection. Other features include linear current setting using a 10bit DAC, output slew rate programmability, H-Sync and V-Sync inputs to synchronise with a TV, direct PWM mode, under-voltage auto-turnoff, over-voltage auto-turnoff, temperature shutdown and fault interrupt output.
