Document
IR3725
Data Sheet
INPUT POWER MONITOR WITH DIGITAL INTERFACE
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FEATURES
DESCRIPTION
The IR3725 is a highly configurable power monitor IC that uses proprietary digital technology to measure a 12V rail current, its voltage, or its average power over a user specified time interval. Configuration and result reporting are managed through a serial digital interface. The current is measured as a voltage across a shunt resistance, an input inductor, or a copper trace resistance. The real time voltage and current signals are multiplied, digitized, and averaged over a user selectable averaging interval providing TruePower™ measurement of highly dynamic loads.
Accurate power, current, or voltage reporting 1.5 % maximum power error 1.0 % maximum current error Serial digital interface SMBus and I2C compatible Programmable averaging interval Flexible current sensing Resistive or Inductor DCR Applications Synchronous rectified buck converters Multiphase converters 12pin 3x4 DFN lead free RoHS Compliant
TYPICAL APPLICATION CIRCUIT
+12V
L
Input Capacitors
Buck Regulators
3.3V
VDD To system Controller
DCR CCS1 IR3725
VO I2C
CCS2
ALERT#
2
VT VCS2 ADDR VCS1 GND
RT
0.1 uF
+12V Return
ORDERING INFORMATION
Device IR3725MTRPBF IR3725MPBF Package 12 lead DFN (4x3 mm body) 12 lead DFN (4x3 mm body) Order Quantity 3000 piece reel Sample Quantity
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2008_12_09
IR3725
Data Sheet
ABSOLUTE MAXIMUM RATINGS
All voltages referenced to GND www.datasheet4u.com VDD: ................................................................3.9V ALERT#:...........................................................3.9V ALERT#............................................. < VDD + 0.3V VCS1, VCS2, VO ...........................................25.0V All other Analog and Digital pins ......................3.9V Operating Junction Temperature .... -10°C to 150oC Storage Temperature Range .......... -65oC to 150oC Thermal Impedance (θJC)..........................1.6 °C/W Thermal Impedance (θJA)...........................30 °C/W ESD Rating ......... HBM Class 1C JEDEC Standard MSL Rating ..................................................Level 2 Reflow Temperature ..................................... 260°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications are not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
VDD = 3.3V ± 5%, 0 C ≤ TJ ≤ 125 C, 8V ≤ VO ≤ 23.5V, and operation in the typical application circuit. See notes following table. PARAMETER BIAS SUPPLY VDD Turn-on Threshold, VDDUP VDD Turn-off Threshold, VDDDN VDD UVLO Hysteresis VDD Operating Current VDD Shutdown Current VOLTAGE REFERENCE VT Voltage Reference load, RT VOLTAGE SENSOR Voltage, full scale, VFS CURRENT SENSOR Voltage, Current Gain, VIG DIGITIZER Internal Sampling frequency External Sampling frequency POWER INFORMATION Minimum Averaging Interval Maximum Averaging Interval TEST CONDITION NOTE MIN TYP MAX 3.1 2.4 75 RT = 25.5 kΩ Config Reg enable bit d4=1 RT = 25.5 kΩ 1 1.40 20 700 18 1.50 25.5 23.5 RT = 25.5 kΩ Driven from internal clock Driven from external clock Config Reg [d3..d0] = b‘0000 Config Reg [d3..d0] = b‘1000 1 1 1.48 512 1024 1 256 1000 100 1.60 45.3 UNIT V V mV μA μA V kΩ V V kHz kHz ms ms
ELECTRICAL SPECIFICATIONS Unless otherwise specified, these specifications apply: o o
922 0.85 217
1126 1.15 295
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2008_12_09
IR3725
Data Sheet
PARAMETER ACCURACY
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TEST CONDITION VO=12V, DCR voltage = 75 mV, RT=25.5kΩ, RCS1=RCS2=1.5kΩ Tj = 0 - 85 °C VO=12 V, DCR voltage = 75mV, RT=25.5kΩ, RCS1=RCS2=1.5kΩ Tj = 0 – 85 °C VO=12V, DCR voltage = 75 mV, RT=25.5kΩ, RCS1=RCS2=1.5kΩ Tj = 0 – 85 °C
NOTE
MIN
TYP
MAX 2 1.5
UNIT
Power measurement error
1, 2
%
Voltage measurement error
1, 2
1.5 1.3
%
Current measurement error
1, 2
1.6 1.0
%
NOTES: 1. 2.
Guaranteed by design, not tested in production Assumes no error contributed by external components
BLOCK DIAGRAM
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2008_12_09
IR3725
Data Sheet
PIN DESCRIPTION
NAME
VCS1 www.datasheet4u.com VCS2 VO VT GND VDD EXTCLK ADDR SCL SDA ALERT# NC
NUMBER
1 2 3 4 5 6 7 8 9 10 11 12
I/O LEVEL
Analog 12V Analog 12V Analog 12V Analog 0V 3.3V 3.3V Digital 3.3V Digital 3.3V Digital 3.3V Digital 3.3V Digital
DESCRIPTION
Current sensing input 1 Current sensing input 2 Voltage sensing input Thermistor sensing input IC bias supply and signal ground 3.3V bias supply Input for optional external clock Bus Address selection input Bus Clock; Input only Bus Data; Input / Open drain output Programmable output function; Open drain output clamped to VDD Do not connect
IC PIN FUNCTIONS
VDD PIN This pin provides operationa.