IR3721MTRPBF International Rectifier, IR3721MTRPBF Datasheet - Page 7

• Manufacturer Part Number: IR3721MTRPBF
• Description: IC POWER SUPPLY MONITOR 10-DFN
• Manufacturer: International Rectifier
• Series: TruePower™r

Specifications of IR3721MTRPBF

• Applications: Power Supply Monitor
• Voltage - Supply: 3.135 V ~ 3.465 V
• Current - Supply: 350µA
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 10-DFN
• Quiescent Current: 450µA
• Bandwidth: 589kHz
• Sensor Case Style: DFN
• No. Of Pins: 10
• Supply Voltage Range: 3.135V To 3.465V
• Operating Temperature Range: 0°C To +125°C
• Filter Terminals: SMD
• Rohs Compliant: No
• Accuracy %: 2.5%
• 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
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Input: -
• Other names: IR3721MTRPBFTR

TYPICAL 2-PHASE DCR SENSING APPLICATION
The IR3721 is capable of monitoring power in a
multiphase converter. A Two Phase DCR Sensing
Circuit is shown below. The voltage output of any
phase is equal to that of any and every other phase
because they are electrically connected and
monitored at VO as before.
Output current is the sum of the two inductor currents
(I
function for multiphase sensing. The voltage on R
due to I
Likewise, the voltage on RCS2 due to IL2 is
The current through R
currents is I
Page 7 of 16
L1
+ I
L2
I
L1
). Superposition is used to derive the transfer
CS
is
I
I
=
L
L
CS
2
1
R
⋅
⋅
. From the two equations above
DCR
CS
DCR
I
L
1
1
R
DCR
CS
1
2
⋅
⋅
2
R
CS2
R
1
+
R
CS
CS
R
CS
(
due to both inductor
1
(
CS
R
3
R
3
+
CS
+
1
CS
+
(
R
R
(
2
I
R
CS
2
L
CS
||
2
CS
||
DCR
3
R
R
2
2
+
CS
CS
||
||
R
R
3
Figure 3 Two Phase DCR Sensing Circuit
R
1
CS
2
CS
)
)
R
CS
2
3
CS
R
1
)
)
www.irf.com
1
CS
3
CS2
The duty ratio of DI is
If DCR1=DCR2, and RCS1=RCS3, then I
simplified to
and the DI duty ratio simplifies to
Full scale current occurs when DI duty ratio becomes
one.
DI
DUTYRATIO
I
DI
CS
DUTYRATIO
=
(
=
I
L
R
1
(
(
CS
R
I
+
L
CS
1
1
I
L
+
=
+
1
2
I
⋅ )
2
+
L
I
CS
2
R
V
2
DCR
⋅ )
R
REF
CS
⋅
DCR
CS
R
2
T
DATA SHEET
1
2
⋅ )
IR3721
⋅
V
R
09/15/08
CS
R
T
Τ
can be