REV. C
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a
AD7813
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2000
2.7 V to 5.5 V, 400 kSPS
8-/10-Bit Sampling ADC
FUNCTIONAL BLOCK DIAGRAM
V
IN
COMP
CONVST
V
DD
AGND
V
REF
CHARGE
REDISTRIBUTION
DAC
DB7
THREE-
STATE
DRIVERS
CLOCK
OSC
BUSY
CS RD
DB0
CONTROL
LOGIC
T/H
AD7813
FEATURES
8-/10-Bit ADC with 2.3 s Conversion Time
On-Chip Track and Hold
Operating Supply Range: 2.7 V to 5.5 V
Specifications at 2.7 V–3.6 V and 5 V 10%
8-Bit Parallel Interface
8-Bit + 2-Bit Read
Power Performance
Normal Operation
10.5 mW, V
DD
= 3 V
Automatic Power-Down
34.6 W @ 1 kSPS, V
DD
= 3 V
Analog Input Range: 0 V to V
REF
Reference Input Range: 1.2 V to V
DD
GENERAL DESCRIPTION
The AD7813 is a high-speed, microprocessor-compatible,
8-/10-bit analog-to-digital converter with a maximum through-
put of 400 kSPS. The converter operates off a single 2.7 V to
5.5 V supply and contains a 2.3 µs successive approximation
A/D converter, track/hold circuitry, on-chip clock oscillator and
8-bit wide parallel interface. The parallel interface is designed to
allow easy interfacing to microprocessors and DSPs. The 10-bit
conversion result is read by carrying out two 8-bit read opera-
tions. The first read operation accesses the 8 MSBs of the ADC
conversion result and the second read accesses the 2 LSBs.
Using only address decoding logic the AD7813 is easily mapped
into the microprocessor address space.
When used in its power-down mode, the AD7813 automatically
powers down at the end of a conversion and powers up at the
start of a new conversion. This feature significantly reduces the
power consumption of the part at lower throughput rates. The
AD7813 can also operate in a high speed mode where the part is
not powered down between conversions. In this mode of opera-
tion the part is capable of providing 400 kSPS throughput.
The part is available in a small, 16-lead, 0.3" wide, plastic dual-
in-line package (DIP), in a 16-lead, 0.15" wide, narrow body
small outline IC (SOIC) and in a 16-lead thin shrink small
outline package (TSSOP).
PRODUCT HIGHLIGHTS
1. Low Power, Single Supply Operation
The AD7813 operates from a single 2.7 V to 5.5 V supply
and typically consumes only 10.5 mW of power. The power
dissipation can be significantly reduced at lower through-
put rates by using the automatic power-down mode.
2. Automatic Power-Down
The automatic power-down mode, whereby the AD7813
goes into power-down mode at the end of a conversion and
powers up before the next conversion, means the AD7813
is ideal for battery powered applications; e.g., 34.6 µW
@ 1 kSPS. (See Power vs. Throughput Rate section.)
3. Parallel Interface
An easy to use 8-bit-wide parallel interface allows interfacing
to most popular microprocessors and DSPs with minimal
external circuitry.
4. Dynamic Specifications for DSP Users
In addition to the traditional ADC specifications, the AD7813
is specified for ac parameters, including signal-to-noise ratio
and distortion.
