ADC0820
8-Bit High Speed µP Compatible A/D Converter with
Track/Hold Function
General Description
By using a half-flash conversion technique, the 8-bit
ADC0820 CMOS A/D offers a 1.5 µs conversion time and
dissipates only 75 mW of power. The half-flash technique
consists of 32 comparators, a most significant 4-bit ADC and
a least significant 4-bit ADC.
The input to the ADC0820 is tracked and held by the input
sampling circuitry eliminating the need for an external
sample-and-hold for signals moving at less than 100 mV/µs.
For ease of interface to microprocessors, the ADC0820 has
been designed to appear as a memory location or I/O port
without the need for external interfacing logic.
Key Specifications
n Resolution 8 Bits
n Conversion Time 2.5 µs Max (RD Mode)
1.5 µs Max (WR-RD Mode)
n Low Power 75 mW Max
n Total Unadjusted
Error ±
1
⁄2 LSB and ± 1 LSB
Features
n Built-in track-and-hold function
n No missing codes
n No external clocking
n Single supply — 5 V
DC
n Easy interface to all microprocessors, or operates
stand-alone
n Latched TRI-STATE
®
output
n Logic inputs and outputs meet both MOS and T
2
L
voltage level specifications
n Operates ratiometrically or with any reference value
equal to or less than V
CC
n 0V to 5V analog input voltage range with single 5V
supply
n No zero or full-scale adjust required
n Overflow output available for cascading
n 0.3" standard width 20-pin DIP
n 20-pin molded chip carrier package
n 20-pin small outline package
n 20-pin shrink small outline package (SSOP)
Connection and Functional Diagrams
TRI-STATE
®
is a registered trademark of National Semiconductor Corporation.
Dual-In-Line, Small Outline
and SSOP Packages
DS005501-1
Top View
Molded Chip Carrier
Package
DS005501-33
June 1999
ADC0820
8-Bit
High
Speed
µP
Compatible
A/D
Converter
with
T
rack/Hold
Function
© 1999 National Semiconductor Corporation DS005501 www.national.com