LTC1329

The LTC1329-10/LTC1329-50 are micropower 8-bit current output D/A converters (DACs) with an output range of 0µA to 10µA and 0µA to 50µA for the -10 and -50 versions respectively. In 3.3V or 5V systems, the DAC current output can be biased from –17V to 2V or –17V to 2.5V respectively. The supply current is only 0.2µA in Shutdown.

The LTC1329 can communicate with external circuitry by using one of three interface modes: standard SPI mode and two pulse modes. Upon power-up, the internal counter resets to 80H, the DAC output assumes mid-range and the chip is configured to SPI or pulse mode depending on the signal level at CS.

In SPI mode, the system MPU can serially transfer 8-bit data to and from the LTC1329. In pulse mode, the upper six bits of the DAC output can be programmed for increment-only (1-wire interface) or increment/decrement (2-wire interface) operation depending on the signal level at D_IN. In increment-only operation, when counter increases beyond full scale, the counter rolls over and sets the DAC to zero. In this way, a single pulse applied to CLK increases the upper six bits of the counter by one step and 63 pulses decrease them by one step. In increment/decrement, the counter stops incrementing at full scale and decrementing at zero and will not roll over.

LTC1329 is available in 8-pin PDIP and SO packages.

Applications

• LCD Contrast Control
• Backlight Brightness Control
• Power Supply Voltage Adjustment
• Battery Charger Current/Voltage Adjustment
• GaAs FET Bias Adjustment
• Trimmer Pot Elimination
• Low Power and Battery-Operated Systems
• Handheld or Portable Instruments