4-Channel, 12-/10-/8-Bit ADC with I2C-
Compatible Interface in 8-Lead SOT-23
AD7991/AD7995/AD7999
FEATURES
FUNCTIONAL BLOCK DIAGRAM
V
DD
12-/10-/8-bit ADCs with fast conversion time: 1 μs typical
4 analog input channels/3 analog input channels with
reference input
Specified for VDD of 2.7 V to 5.5 V
Sequencer operation
Temperature range: −40°C to +125°C
I2C-compatible serial interface supports standard, fast,
and high speed modes
2 versions allow 2 I2C addresses
Low power consumption
V
V
V
IN0
IN1
IN2
12-/10-/8-BIT
SAR
I/P
MUX
T/H
ADC
V
/V
IN3 REF
CONTROL
SCL
SDA
LOGIC AND
2
I C
INTERFACE
Shutdown mode: 1 μA maximum
8-lead SOT-23 package
AD7991/AD7995/AD7999
GND
APPLICATIONS
Figure 1.
System monitoring
Battery-powered systems
Data acquisition
Medical instruments
GENERAL DESCRIPTION
The AD7991/AD7995/AD7999 are 12-/10-/8-bit, low power,
successive approximation ADCs with an I2C®-compatible interface.
Each part operates from a single 2.7 V to 5.5 V power supply and
features a 1 μs conversion time. The track-and-hold amplifier
allows each part to handle input frequencies of up to 14 MHz,
and a multiplexer allows taking samples from four channels.
ADC is 0 V to VDD. An external reference, applied through the
IN3/VREF input, can also be used with this part.
V
PRODUCT HIGHLIGHTS
1. Four single-ended analog input channels, or three single-
ended analog input channels and one reference input channel.
2. I2C-compatible serial interface. Standard, fast, and high
speed modes.
3. Automatic shutdown.
4. Reference derived from the power supply or external
reference.
Each AD7991/AD7995/AD7999 provides a 2-wire serial
interface compatible with I2C interfaces. The AD7991 and
AD7995 come in two versions and each version has an
individual I2C address. This allows two of the same devices to be
connected to the same I2C bus. Both versions support standard,
fast, and high speed I2C interface modes. The AD7999 comes in
one version.
5. 8-lead SOT-23 package.
Table 1. Related Devices
Device
AD7998
AD7997
AD7994
AD7993
AD7992
Resolution
Input Channels
The AD7991/AD7995/AD7999 normally remain in a shutdown
state, powering up only for conversions. The conversion process
is controlled by a command mode, during which each I2C read
operation initiates a conversion and returns the result over the
I2C bus.
12
10
12
10
12
8
8
4
4
2
When four channels are used as analog inputs, the reference for
the part is taken from VDD; this allows the widest dynamic input
range to the ADC. Therefore, the analog input range to the
Rev. 0
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