Easily programmed by serial interfaced microcontroller ports, the AD8801 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 AD8803 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 AD8801/AD8803 contain eight voltage output digital-to-analog converters, sharing a common reference voltage input.
Each DAC has its own DAC register that holds its output state. These DAC registers are updated from an internal serial-to-parallel shift register that is loaded from a standard three-wire serial input digital interface. Eleven data bits make up the data word clocked into the serial input register. This data word is decoded where the first 3 bits determine the address of the DAC register to be loaded with the last 8 bits of data. The AD8801/AD8803 consumes only 5 mA from 5 V power supplies. In addition, in shutdown mode reference input current consumption is also reduced to 5 µA while saving the DAC latch settings for use after return to normal operation.
The AD8801/AD8803 is available in 16-pin plastic DIP and the 1.5 mm height SO-16 surface mount packages.
