+2.7 V to +5.5 V, 400 kSPS
8-/10-Bit Sampling ADC
a
AD7813
FUNCTIONAL BLOCK DIAGRAM
FEATURES
8-/10-Bit ADC with 2.3 ꢀs Conversion Time
On-Chip Track and Hold
V
V
REF
AGND
DD
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
DB7
DB0
AD7813
CHARGE
REDISTRIBUTION
DAC
THREE-
STATE
DRIVERS
CLOCK
OSC
Normal Operation
10.5 mW, VDD = 3 V
Automatic Power-Down
CONTROL
LOGIC
COMP
V
T/H
IN
34.6 ꢀW @ 1 kSPS, VDD = 3 V
Analog Input Range: 0 V to VREF
Reference Input Range: 1.2 V to VDD
BUSY CS RD CONVST
GENERAL DESCRIPTION
PRODUCT HIGHLIGHTS
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.
1. Low Power, Single Supply Operation
The AD7813 operates from a single +2.7 V to +5.5 V sup-
ply and typically consumes only 10.5 mW of power. The
power dissipation can be significantly reduced at lower
throughput 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
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.
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.
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).
REV. B
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use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
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© Analog Devices, Inc., 2000