IR3721MPBF International Rectifier, IR3721MPBF Datasheet - Page 5
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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
FUNCTIONAL DESCRIPTION
Please refer to the Functional Description Diagram
below. Power flow from the buck converter inductor is
the product of output voltage times the current I
flowing through the inductor.
Power is measured with the aid of International
Rectifier’s proprietary TruePower™ circuit. Current is
converted to a duty ratio that appears at the DI pin.
The duty ratio of the DI pin is
The full-scale current that can be measured
corresponds to a duty ratio of one.
Page 5 of 16
Vin
DI
DUTY
RATIO
Equation 1
=
(
R
CS
I
L
R
1
⋅
CS1
DCR
+
R
L
CS
I
2
Figure 1 Functional Description Diagram
L
)
C
⋅
V
DCR
CS1
R
R
R
T
CS2
Τ
www.irf.com
C
CS2
L
R
T
VCS
V
VO
RT
The amplitude of the DI pin is the voltage appearing
at pin VK. If a fixed voltage is applied to VK then the
output of the RC filter driven by DI will be proportional
to inductor current I
If VO is applied to V
output of the DI driven RC network will be
proportional to power. The full-scale voltage that can
be measured is established on the chip to be 1.8V.
The full scale power P
product of full-scale voltage and full scale current.
IR3721
VDD
GND
L
K
.
as shown in the figure then the
FS
that can be measured is the
DI
VK
DATA SHEET
IR3721
Power
09/15/08
Vo