Texas Instruments Incorporated (TI) has introduced two 16-channel, constant-current sink, light-emitting diode (LED) drivers with dot correction and grayscale on one integrated circuit (IC) for high-quality video. The drivers give designers increased system reliability and dynamic brightness control to enhance the resolution for large-panel mono-, multi- or full-color LED displays, LED signboards and display backlighting.
An extension of TI's popular TLC5940 family, the new TLC5942 and TLC5945 provide high-performance capabilities, such as analogue and digital dimming, in an integrated IC for large LED displays. The TLC5942 provides 128 step dot correction to compensate for LED luminous mismatch, and allows for both grayscale control and dot correction to be accessible via separate, dedicated serial interface ports. The maximum current value of all 16 channels can be set by a single external resistor. Higher currents can be provided by paralleling channels. The TLC5945 is optimised for video displays with fast video action, such as stadium sporting events, as it provides a fast refresh rate capability - 30-MHz data transfer rate - with no delay.
Both the TLC5942 and TLC5945 have two error detection circuits for LED open detection (LOD) and a thermal error flag (TEF). The LOD identifies a broken or disconnected LED during the display period. TEF indicates an over-temperature condition, meaning when the TEF is set, all output drivers are turned off. When the device has cooled the TEF is cleared and all output drivers are restarted.
Additional features of the TLC5942 include 50-mA capability (constant-current sink); 12-bit (4,096 steps) grayscale control with PWM; 7-bit (128 steps) dot correction with sink current; LED power-supply voltage up to 17 V; device bias power-supply 3.0 V to 5.5 V; constant-current accuracy - channel-to-channel = ±1.5% and device-to-device = ±3%; CMOS level I/O; 30-MHz data transfer rate; thermal shutdown (TSD) - automatic shutdown at high temperature conditions and restart under normal temperature; noise reduction with 4-channel grouped delay to prevent inrush current; and -40°C to +85°C operating temperature.
The TLC59xx family is shipping in volume from TI and its worldwide network of distributors and is available in a 32-pin QFN or 28-pin HTSSOP package.
