
AD7994/AD7993
a
Preliminary Technical Data
REV. PrF 09/03
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Analog Devices, Inc., 200
3
4-Channel, 12-/10-Bit ADCs with I
2
C Compatible
Interface in 16-Lead TSSOP
PRELIMINARY TECHNICAL DATA
FUNCTIONAL BLOCK DIAGRAM
FEATURES
12-Bit ADC with Fast Conversion Time: 2
μ
s
Four Single-Ended Analog Input Channels
Specified for V
DD
of 2.7 V to 5.5 V
Low Power Consumption
Fast Throughput Rate:- 188 KSPS
Sequencer Operation
Automatic Cycle Mode
I
2
C
R
Compatible Serial Interface
I
2
C
R
Interface supports:
Standard, Fast, and High-Speed Modes
Out of Range Indicator/Alert Function
Pin-Selectable Addressing via AS
Two Versions Allow Five I
2
C Addresses
Shutdown Mode: 1
μ
A max
16-Lead TSSOP Package
GENERAL DESCRIPTION
The AD7994/AD7993 are 4 channel, 12-/10-bit, high
speed, low power, successive-approximation ADCs re-
spectively. They operate from a single 2.7 V to 5.5 V
power supply and feature a conversion time of 2
μ
s. The
parts contain a four channel multiplexer and track/hold
amplifier which can handle input frequencies in excess of
TBD kHz.
The AD7994/AD7993 provide a two-wire serial interface
which is compatible with I
2
C interfaces. The parts come
in two versions, AD7994-0/AD7993-0 to AD7994-1/
AD7993-1. Each version allows for a minimum of two
different I
2
C addresses. The I
2
C interface on the AD7994-
0/AD7993-0 supports Standard and Fast I
2
C Interface
Modes. The I
2
C interface on the AD7994-1/AD7993-1
supports Standard, Fast and two High-Speed I
2
C Interface
Modes.
The AD7994/AD7993 normally remain in a shutdown
state while not converting, powering up only for conver-
sions. The conversion process can be controlled using the
CONVST
pin, an Automatic Conversion Cycle selected
through software control, or a mode where conversions
occur across Write operations. There are no pipeline de-
lays associated with the part.
The reference for the part is applied externally to the
REF
IN
pin and can be in the range of 1.2V to V
DD.
This
allows the widest dynamic input range to the ADC.
PRODUCT HIGHLIGHTS
1. 2
μ
s Conversion time with low power consumption.
2. I
2
C Compatible Serial Interface with pin selectable
addresses. Two AD7994/AD7993 versions allow five
AD7994/AD7993 devices to be connected to the same
serial bus.
3. The parts feature automatic shutdown while not convert-
ing to maximize power efficiency. Current consumption
is 1
μ
A max when in shutdown.
4. Reference can be driven up to the power supply.
5. Out of Range Indicator which can be software disabled/
enabled.
6. Oneshot and automatic conversion rates.
7. No Pipeline Delay
The part features a standard successive-approximation
ADC.
SMBus is a trademark and I
2
C is a registered trademark of Philips Corporation
T/H
VIN1
VIN2
VIN3
VIN4
12-/10-BIT
SUCCESSIVE
APPROXIMATION
ADC
CONTROL
LOGIC
I/P
MUX
AD7994/AD7993
VDD
SCL
I2C INTERFACE
CONVERSION
RESULT REGISTER
CONFIGURATION
REGISTER
CYCLE TIMER
REGISTER
ALERT STATUS
REGISTER
SDA
GND
ALERT
GND
AS
OSCILLATOR
REFIN
DATALOW LIMIT
REGISTER CH1-CH4
DATAHIGH LIMIT
REGISTER CH1-CH4
HYSTERESIS
REGISTER CH1-CH4
On-chip registers can be programmed with high and low
limits for the conversion result, and an open drain Out of
Range Indicator output (ALERT), becomes active when
the programmed high or low limits are violated by the
conversion result. This output can be used as an interrupt.