Datasheet

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General Description

The MAX4172 is a low-cost, precision, high-side current-

sense amplifier for portable PCs, telephones, and other

systems where battery/DC power-line monitoring is critical.

High-side power-line monitoring is especially useful in

battery-powered systems, since it does not interfere with

the battery charger’s ground path. Wide bandwidth and

ground-sensing capability make the device suitable for

closed-loop battery-charger and general-purpose current-

source applications. The 0 to 32V input common-mode

range is independent of the supply voltage, which ensures

that current-sense feedback remains viable, even when

connected to a battery in deep discharge.

To provide a high level of flexibility, the MAX4172 functions

with an external sense resistor to set the range of load

current to be monitored. It has a current output that can

be converted to a ground-referred voltage with a single

resistor, accommodating a wide range of battery voltages

and currents.

An open-collector power-good output (PG) indicates

when the supply voltage reaches an adequate level

to guarantee proper operation of the current-sense

amplifier. The MAX4172 operates with a 3.0V to 32V

supply voltage, and is available in a space-saving, 8-pin

μMAX

or SO package.

Applications

● Portable PCs: Notebooks/Subnotebooks/Palmtops

● Battery-Powered/Portable Equipment

● Closed-Loop Battery Chargers/Current Sources

● Smart-Battery Packs

● Portable/Cellular Phones

● Portable Test/Measurement Systems

● Energy Management Systems

Benets and Features

● Ideal for High-Side Monitoring

• 3V to 32V Supply Operation

• ±0.5% Typical Full-Scale Accuracy Over Temperature

• High Accuracy +2V to +32V Common-Mode

Range, Functional Down to 0V, Independent of

Supply Voltage

• 800kHz Bandwidth [V

SENSE

= 100mV (1C)]

• 200kHz Bandwidth [V

SENSE

= 6.25mV (C/16)]

● Minimizes Board Space Requirements

• μMAX and SO Packages

19-1184; Rev 5; 12/20

μMAX is a registered trademark of Maxim Integrated Products, Inc.

Click here to ask about the production status of specic part numbers.

+Denotes a lead(Pb)-free/RoHS-compliant package.

Ordering Information

Typical Operating Circuit

Pin Conguration

OUT

GND

FEEDBACK LOOP

LOW-COST BATTERY CHARGER/CURRENT SOURCE

OUT

= 500mV/A

OUT

1kΩ

100kΩ

ANALOG OR

LOGIC SUPPLY

0 TO 32V

OUT

SENSE

/ 100Ω

V+

RS+

SENSE

50mΩ

SENSE

RS-

MAX4172

POWER GOOD

LOAD/

BATTERY

LOW-COST

SWITCHING

REGULATOR

UNREGULATED

DC SUPPLY

3V TO 32V

TOP VIEW

OUT

GND

N.C.

V+

RS-

N.C.

RS+

µMAX/SO

MAX4172

PART TEMP RANGE PIN-PACKAGE

MAX4172ESA+ -40°C to +85°C 8 SO

MAX4172EUA+ -40°C to +85°C 8 μMAX

MAX4172GUA+ -40°C to +105°C 8 µMAX

MAX4172 Low-Cost, Precision, High-Side

Current-Sense Amplifier

Summary of content (9 pages)

PAGE 1
Click here to ask about the production status of specific part numbers. MAX4172 Low-Cost, Precision, High-Side Current-Sense Amplifier General Description The MAX4172 is a low-cost, precision, high-side currentsense amplifier for portable PCs, telephones, and other systems where battery/DC power-line monitoring is critical. High-side power-line monitoring is especially useful in battery-powered systems, since it does not interfere with the battery charger’s ground path.
PAGE 2
MAX4172 Low-Cost, Precision, High-Side Current-Sense Amplifier Absolute Maximum Ratings V+, RS+, RS-, PG..................................................-0.3V to +36V OUT..............................................................-0.3V to (V+ + 0.3V) Differential Input Voltage, VRS+ - VRS-...........................±700mV Current into Any Pin..........................................................±50mA Continuous Power Dissipation (TA = +70°C) SO (derate 5.88mW/°C above +70°C)........................
PAGE 3
MAX4172 Low-Cost, Precision, High-Side Current-Sense Amplifier Electrical Characteristics (continued) (V+ = +3V to +32V; VRS+, VRS- = 0 to 32V; TA = TMIN to TMAX; unless otherwise noted. Typical values are at V+ = +12V, VRS+ = 12V, TA = +25°C.) PARAMETER SYMBOL CONDITIONS Maximum Output Voltage (OUT) MIN TYP IOUT ≤ 1.5mA VSENSE = 100mV Bandwidth Maximum Output Current Transconductance V+ Threshold for PG Output Low (Note 2) PG Output Low Voltage VOL Leakage Current into PG V+ - 1.
PAGE 4
MAX4172 Low-Cost, Precision, High-Side Current-Sense Amplifier Typical Operating Characteristics (continued) (V+ = +12V, VRS+ = 12V, ROUT = 1kΩ, TA = +25°C, unless otherwise noted.) 35 MAX4172-04 40 35 ERROR (%) 20 15 20 15 10 5mVP-P 5 0 0.1m 10m 1m 100m 0.1 1 10 100 1000 POWER-SUPPLY FREQUENCY (kHz) OUTPUT ERROR vs. COMMON MODE VOLTAGE V+ THRESHOLD FOR PG OUTPUT LOW vs. TEMPERATURE VSENSE = 100mV TA = -40°C TA = +105°C 2.98 2.88 V+ TRIP THRESHOLD (V) 0.6 -0.2 0.
PAGE 5
MAX4172 Low-Cost, Precision, High-Side Current-Sense Amplifier Typical Operating Characteristics (continued) (V+ = +12V, VRS+ = 12V, ROUT = 1kΩ, TA = +25°C, unless otherwise noted.) STARTUP DELAY V+ to PG POWER-UP DELAY MAX4172-10 VOUT 500mV/div MAX4172-11 PG 2V/div GND GND V+ 2V/div V+ 2V/div GND GND 5µs/div VSENSE = 100mV 10ms/div 100kW PULLUP RESISTOR FROM PG TO +4V Pin Description PIN NAME 1 RS+ Power connection to the external sense resistor.
PAGE 6
MAX4172 ILOAD x RSENSE. Then, since IRG1 flows through RG1, IRG1 x RG1 = ILOAD x RSENSE. The internal current mirror multiplies IRG1 by a factor of 50 to give IOUT = 50 x IRG1. Substituting IOUT/50 for IRG1, (IOUT/50) x RG1 = ILOAD x RSENSE, or: Low-Cost, Precision, High-Side Current-Sense Amplifier RS+ OUT is a high-impedance current source that can be integrated by connecting it to a capacitive load.
PAGE 7
MAX4172 Low-Cost, Precision, High-Side Current-Sense Amplifier Table 1. Suggested Component Values FULL-SCALE LOAD CURRENT (A) CURRENT-SENSE RESISTOR, RSENSE (mΩ) OUTPUT RESISTOR, ROUT (kΩ) FULL-SCALE OUTPUT VOLTAGE, VOUT (V) SCALE FACTOR, VOUT/ISENSE (V/A) 0.1 1000 3.48 3.48 34.8 1 100 3.48 3.48 3.48 5 20 3.48 3.48 0.696 10 10 3.48 3.48 .
PAGE 8
MAX4172 Low-Cost, Precision, High-Side Current-Sense Amplifier Power-Supply Bypassing and Grounding In most applications, grounding the MAX4172 requires no special precautions. However, in high-current systems, large voltage drops can develop across the ground plane, which can add to or subtract from VOUT. Use a single-point star ground for the highest currentmeasurement accuracy.
PAGE 9
MAX4172 Low-Cost, Precision, High-Side Current-Sense Amplifier Revision History REVISION NUMBER REVISION DATE PAGES CHANGED 0 12/96 Initial release 1 6/10 Clarified 0 to 2V is not a high-accuracy range for the device, removed future product reference, added lead-free options and soldering temperature 2 10/12 Revised the Package Information 8 3 5/15 Revised Benefits and Features section 1 4 6/16 Added G-temp grade for 105°C operation and updated Typical Operating Characteristics section