Adc for Solar Tracking

ADC0803, ADC0804

®

Data Sheet

August 2002

8-Bit, Microprocessor-Compatible, A/D
Converters

FN3094.4

Features

The ADC080X family are CMOS 8-Bit, successiveapproximation A/D converters which use a modified
potentiometric ladder and are designed to operate with the
8080A control bus via three-state outputs. These converters
appear to the processor as memory locations or I/O ports,
and hence no interfacing logic is required.
The differential analog voltage input has good commonmode-rejection and permits offsetting the analog zero-inputvoltage value. In addition, the voltage reference input can be
adjusted to allow encoding any smaller analog voltage span
to the full 8 bits of resolution.

Typical Application Schematic

• 80C48 and 80C80/85 Bus Compatible - No Interfacing
Logic Required
• Conversion Time . . . . . . . . . . . . . . . . . . . . . . . . . . 1kΩ). If input bypass capacitors are necessary for
noise filtering and high source resistance is desirable to
minimize capacitor size, the effects of the voltage drop across
this input resistance, due to the average value of the input
current, can be compensated by a full scale adjustment while
the given source resistor and input bypass capacitor are both
in place. This is possible because the average value of the
input current is a precise linear function of the differential input
voltage at a constant conversion rate.

3

( 5 × 10 ) ( 640 × 10 )
V PEAK = --------------------------------------------------------- ≅ 1.9V .
( 6.28 ) ( 60 ) ( 4.5 )

The allowed range of analog input voltage usually places
more severe restrictions on input common-mode voltage
levels than this.
An analog input voltage with a reduced span and a relatively
large zero offset can be easily handled by making use of the
differential input (see Reference Voltage Span Adjust).

Analog Input Current
The internal switching action causes displacement currents to
flow at the analog inputs. The... [continues]

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