Linear Technology LT8500 pulse width modulation generator

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Linear Technology has announced the LT8500, a pulse width modulation generator with 48 independent channels. Each channel has an individually adjustable 12-bit (4096 steps) PWM register and a 6-bit (64 steps) ±50% correction register.

All controls are programmable via a TTL/CMOS 50 MHz serial data interface. The device can be used in a wide variety of PWM-intensive applications such as LED control, as well as industrial and robotic applications.

For example, it can be used with three LT3595As, 16-channel LED drivers, to deliver 48 independently dimmed LED strings for locally dimmed LED backlighting for large LCDs. The correction resistor allows matching light output of each LED string.

The generator operates from a 3 to 5.5 V input, enabling it to operate from a wide range of standard power buses. For LED applications, each channel has individual 6-bit dot correction current adjustment and 12-bit greyscale PWM dimming.

The 40 ns on-time offers wide dynamic contrast ratios. Both correction and greyscale dimming are accessible via a serial interface in TTL/CMOS logic.

The device offers two diagnostic information flags: synchronisation error and open LED. The flags are sent with additional state information, on the serial data interface during status read back. The 50 MHz cascadable serial data interface includes buffering and skew-balancing, easing the design for PWM-intensive applications such as large-screen LCD dynamic backlighting.