Digital Power Monitor
with Convert Pin and ALERTB Output
ADM1191
FUNCTIONAL BLOCK DIAGRAM
FEATURES
Powered from 3.15 V to 26 V
Precision current sense amplifier
CONV
ADM1191
Precision voltage input
SDA
V
VCC
0
12-bit ADC for current and voltage readback
Convert (CONV) pin for commanding an ADC read
SETV input for setting overcurrent alert threshold
ALERTB output provides an overcurrent interrupt
I2C fast mode-compliant interface (400 kHz maximum)
2 address pins allow 16 devices on the same bus
10-lead MSOP
SCL
A1
2
I C
12-BIT
ADC
I
1
A
SENSE
MUX
A0
CURRENT
SENSE
AMPLIFIER
ALERT
ALERTB
SETV
APPLICATIONS
COMPARATOR
Power monitoring/power budgeting
Central office equipment
GND
Figure 1.
Telecommunications and data communications equipment
PCs/servers
3.15V TO 26V
R
SENSE
GENERAL DESCRIPTION
The ADM1191 is an integrated current sense amplifier that
offers digital current and voltage monitoring via an on-chip
12-bit analog-to-digital converter (ADC), communicated
through an I2C® interface.
VCC
SENSE
ALERTB
CONTROLLER
INTERRUPT
P = VI
ADM1191
SDA
SDA
SCL
SETV
An internal current sense amplifier measures voltage across the
sense resistor in the power path via the VCC pin and the SENSE pin.
SCL
CONV
CONV
A 12-bit ADC can measure the current seen in the sense
resistor, as well as the supply voltage on the VCC pin.
A1
A0
GND
An industry-standard I2C interface allows a controller to read
current and voltage data from the ADC. Measurements can be
initiated by an I2C command or via the convert (CONV) pin.
The CONV pin is especially useful for synchronizing reads on
multiple ADM1191 devices. Alternatively, the ADC can run
continuously, and the user can read the latest conversion data
whenever it is required. Up to 16 unique I2C addresses can be
created, depending on the way the A0 pin and the A1 pin are
connected.
Figure 2. Applications Diagram
The ALERTB output can be used as a flag to warn a micro-
controller or field programmable gate array (FPGA) of an
overcurrent condition. ALERTB outputs of multiple ADM1191
devices can be tied together and used as a combined alert.
The ADM1191 is packaged in a 10-lead MSOP.
A SETV pin is also included. A voltage applied to this pin is
internally compared with the output voltage on the current
sense amplifier. The output of the SETV comparator asserts
when the current sense amplifier output exceeds the SETV
voltage. When this event occurs, the ALERTB output asserts.
Rev. B
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