IR3721MPBF International Rectifier, IR3721MPBF Datasheet - Page 4
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IR3721MPBF
Manufacturer Part Number
IR3721MPBF
Description
Power Monitor IC with Analog Output
Manufacturer
International Rectifier
Datasheet
1.IR3721MPBF.pdf
(16 pages)
Specifications of IR3721MPBF
Package
10 Lead 3x3 DFN
Static Accuracy
2.5% @ 65oC
Vk Range
0.5V - 1.8V
Vcs Range
5mV - 150mV
Bias Supply Voltage
+3.3V +/-5%
Junction Temperature
0oC to 125oC
Pbf
Yes
IC PIN FUNCTIONS
VDD PINS
These pins provide operational bias current to circuits
internal to the IR3721. Bypass them with a high
quality ceramic capacitor to the GND pins.
GND PINS
These pins return operational bias current to system
ground. VO is measured with respect to GND. The
GND pin sinks reference current established by the
external resistor R
VO PIN
Since this pin measures DCR voltage drop it is critical
that it be Kelvin connected to the buck inductor
output. Power accuracy may be degraded if the
voltage at this pin is below VO
VCS PIN
A switched current source internal to the IR3721
maintains the average voltage of this pin equal to the
voltage of the VO pin. The average current into this
pin is therefore proportional to buck inductor current.
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VRT PIN
A voltage reference internal to the IR3721 drives the
V
set the amplitude of the current monitor switched
current source I
a precision resistor network R
include provision for canceling the positive
temperature coefficient of the buck inductor’s DC
resistance (DCR).
VK PIN
The voltage of the VK pin is used to modulate the
amplitude of the DI pin. This is one of the terms used
to determine the product of the multiplier output. If VK
is connected to a fixed voltage then the output of the
multiplier is proportional to current. If VK is connected
to the buck converter output voltage then the output
of the DI driven RC filter is proportional to power.
DI PIN
The Dl pin output has a duty ratio proportional to the
current into VCS, and an amplitude equal to the
voltage at the VK pin. The DI pin is intended to drive
an external low pass filter. The output of this filter is
the product of the current and voltage terms.
RT
pin while the pin current is monitored and used to
REF
. Connect this pin to GND through
T
. This network may
DATA SHEET
IR3721
09/15/08