Easily programmed by serial interfaced microcontroller ports, the AD8802 with its midscale preset is ideal for potentiometer replacement where adjustments start at a nominal value. Applications such as gain control of video amplifiers, voltage controlled frequencies and bandwidths in video equipment, geometric correction and automatic adjustment in CRT computer graphic displays are a few of the many applications ideally suited for these parts. The AD8804 provides independent control of both the top and bottom end of the potentiometer divider allowing a separate zero-scale voltage setting determined by the VREFL pin. This is helpful for maximizing the resolution of devices with a limited allowable voltage control range.
Internally the AD8802/AD8804 contains 12 voltage-output digital-to-analog converters, sharing a common reference-voltage input.
Each DAC has its own DAC latch that holds its output state. These DAC latches are updated from an internal serial-to-parallel shift register that is loaded from a standard 3-wire serial input digital interface. The serial-data-input word is decoded where the first 4 bits determine the address of the DAC latches to be loaded with the last 8 bits of data. The AD8802/ AD8804 consumes only 10 µA from 5 V power supplies. In addition, in shutdown mode reference input current consumption is also reduced to 10 µA while saving the DAC latch settings for use after return to normal operation.
The AD8802/AD8804 is available in the 20-pin plastic DIP, the SOIC-20 surface mount package, and the 1 mm thin TSSOP-20 package.
