1 Introduction

The TLC5941 is a 16-channel LED driver with 12-bit grayscale dimming and 6-bit dot correction capabilities typically used for high-quality LED displays. The 192 bits of grayscale data and 96 bits of dot correction data are entered into the TLC5941 through a serial interface. This application report presents an example of the firmware necessary to drive the TLC5941 with an MSP430F427 MCU.

The serial interface is comprised of a shift register that is controlled by two signals, SLCK and SIN. One bit of serial data is placed on the SIN pin of the TLC5941; then, a positive edge on the SCLK pin shifts the data into the TLC5941 input register. Once all of the 96 or 192 bits have been shifted in, the XLAT pin is pulsed high to latch the data from the input register into the grayscale or dot correction registers.

The TLC5941 also requires a clock signal, GSCLK, for the grayscale PWM function. This clock is used to drive internal counters to derive the 12-bit grayscale dimming function. After 4096 grayscale clocks, the internal counter must be reset to zero by pulsing the BLANK signal high. This clocking function has also been included in the example MSP430F427 firmware to provide a stand-alone solution.