8-Channel, I
2
C, 12-Bit SAR ADC
Enhanced Product
Rev. 0 Document Feedback
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FEATURES
12-bit SAR ADC
8 single-ended analog input channels
Analog input range: 0 V to 2.5 V
12-bit temperature to digital converter
Temperature sensor accuracy of ±1°C typical
Channel sequencer operation
Specified for V
DD
of 2.8 V to 3.6 V
Logic voltage V
DRIVE
= 1.65 V to 3.6 V
Internal 2.5 V reference
I
2
C-compatible serial interface supports standard and
fast speed modes
Out of range indicator/alert function
Autocycle mode
Power-down current: 13 µA maximum
20-lead LFCSP package
ENHANCED PRODUCT FEATURES
Supports defense and aerospace applications (AQEC
standard)
Extended industrial temperature range: −55°C to +125°C
Controlled manufacturing baseline
1 assembly/test site
1 fabrication site
Product change notification
Qualification data available upon request
FUNCTIONAL BLOCK DIAGRAM
TEMP
SENSOR
12-BIT
SUCCESSIVE
APPROXIMATION
ADC
INPUT
MUX
T/H
V
DD
GND
PD/RST
SCL
SDA
AS1
AS0
V
DRIVE
V
IN7
V
IN0
CONTROL LOGIC
I
2
C INTERFACE
SEQUENCER
V
REF
BUFREF
AD7291-EP
15915-001
ALERT
Figure 1.
GENERAL DESCRIPTION
The AD7291-EP is a 12-bit, low power, 8-channel, successive
approximation analog-to-digital converter (ADC) with an
internal temperature sensor.
The device operates from a single 3.3 V power supply and
features an I
2
C-compatible interface. The device contains a
9-channel multiplexer and a track-and-hold amplifier with an
input bandwidth of 30 MHz. The device has an on-chip 2.5 V
reference that can be disabled to allow the use of an external
reference.
The AD7291-EP provides a 2-wire serial interface compatible
with I
2
C interfaces. The I
2
C interface supports standard and fast
I
2
C interface modes. The AD7291-EP normally remains in a
partial power-down state while not converting and powers up
for conversions. The conversion process can be controlled by a
command mode where conversions occur across I
2
C write
operations or an autocycle mode selected through software control.
The AD7291-EP includes a high accuracy band gap temperature
sensor, which is monitored and digitized by the 12-bit ADC to
give a resolution of 0.25°C.
The AD7291-EP offers a programmable sequencer, which
enables the selection of a preprogrammable sequence of
channels for conversion.
On-chip limit registers can be programmed with high and low
limits for the conversion results; an 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.
Additional application and technical information can be found
in the AD7291 data sheet.
