Power Distribution And Circuitry; Dac Output Circuitry - Waters 2410 Service Manual

Power Distribution and Circuitry

The PCB is broken up into two regions; a digital region, and a "clean" analog region. The digital
area uses the VCC and ground for planes, while the analog section uses the 12-Volt returns for the
analog ground planes. The analog region also has the ± 12 volt input power converted through low
dropout linear regulators to "clean" ± 10 volts for the DACs and ± 5 volts for the front-end
amplifiers and the ADCs.

DAC Output Circuitry

The Analog outputs for the 2410 use a frequency to voltage type digital to analog converter. Three
16 bit counters are used to control period and pulse width. This allows for a more precise conversion.
The following describes how to calculate the counter values for a given output voltage. The voltage
range for the recorder and integrator outputs is –2 to +2 volts. The compression output is –10 to +10
mv that is divided down from the 2v output.
17-9