Rainbow Electronics ADC0809 - Manual (Page 12)

Applications Information
(Continued)
4.0 ANALOG COMPARATOR INPUTS
The dynamic comparator input current is caused by the pe-
riodic switching of on-chip stray capacitances. These are
connected alternately to the output of the resistor ladder/
switch tree network and to the comparator input as part of
the operation of the chopper stabilized comparator.
The average value of the comparator input current varies di-
rectly with clock frequency and with V
IN
as shown in
Figure 6 .
If no filter capacitors are used at the analog inputs and the
signal source impedances are low, the comparator input cur-
rent should not introduce converter errors, as the transient
created by the capacitance discharge will die out before the
comparator output is strobed.
If input filter capacitors are desired for noise reduction and
signal conditioning they will tend to average out the dynamic
comparator input current. It will then take on the characteris-
tics of a DC bias current whose effect can be predicted con-
ventionally.
Typical Application
MICROPROCESSOR INTERFACE TABLE
PROCESSOR READ WRITE INTERRUPT (COMMENT)
8080 MEMR MEMW INTR (Thru RST Circuit)
8085 RD WR INTR (Thru RST Circuit)
Z-80 RD WR INT (Thru RST Circuit, Mode 0)
SC/MP NRDS NWDS SA (Thru Sense A)
6800 VMA • φ 2 • R/W VMA • φ • R/W IRQA or IRQB (Thru PIA)
Ordering Information
TEMPERATURE RANGE −40˚C to +85˚C −55˚C to +125˚C
Error ± 1 ⁄ 2 LSB Unadjusted ADC0808CCN ADC0808CCV ADC0808CCJ ADC0808CJ
± 1 LSB Unadjusted ADC0809CCN ADC0809CCV
Package Outline N28A Molded DIP V28A Molded Chip Carrier J28A Ceramic DIP J28A Ceramic DIP
DS005672-10
*Address latches needed for 8085 and SC/MP interfacing the ADC0808 to a microprocessor
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