Skip to main content

MAX4173FESA Low-Cost High-Side Current Sense Amplifier

The MAX4173FESA is a low-cost, precision, high-side current sense amplifier in the SO-8 Package. It features a voltage output that eliminates the need for gain-setting resistors and is ideal for today’s notebook computers, cell phones, and other systems where current monitoring is critical. High-side current monitoring is especially useful in battery-powered systems since it does not interfere with the ground path of the battery charger. The input common-mode range of 0 to +28V is independent of the supply voltage and ensures that the current-sense feedback remains viable even when connected to a battery in deep discharge. The MAX4173FESA has a wide 1.7MHz bandwidth, making it suitable for use inside battery charger control loops. The MAX4173 operates from a single +3V to +28V supply, typically draws only 420µA of supply current over the extended operating temperature range (-40°C to +85°C)

 

MAX4173FESA Pinout Configuration

Pin Number

Pin Name

Description

1

VCC

Supply Voltage Input. Bypass to GND with a 0.1µF capacitor.

2

NC

No Connection. Not internally connected.

3

GND

Ground

4

OUT

Voltage Output. VOUT is proportional to VSENSE ( VRS+ - VRS- ). Output impedance is approximately 12kΩ.

5

NC

No Connection. Not internally connected.

6

RS-

Load-Side Connection for the External Sense Resistor

7

NC

No Connection. Not internally connected.

8

RS+

Power-Side Connection to the External Sense Resistor

 

Features and Specifications

  • Low-Cost, Compact Current-Sense Solution
  • High Accuracy +2V to +28V Common-Mode Range, Functional Down to 0V, Independent of Supply Voltage
  • Gain: +50V/V
  • ±0.5% Full-Scale Accuracy
  • ±3mV Input Offset Voltage
  • Wide 1.7MHz Bandwidth
  • 420µA Supply Current

Absolute Maximum Ratings

  • VCC, RS+, RS- to GND: 0.3V to +30V
  • OUT to GND: 0.3V to (VCC + 0.3V)
  • Output Short-Circuit to VCC or GND: Continuous
  • Differential Input Voltage (VRS+ - VRS-): ±0.3V
  • Current into Any Pin: ±20mA
  • Continuous Power Dissipation (TA = +70°C)
  • 8-Pin SO (derate 5.88mW/°C above +70°C): 471mW
  • Operating Temperature Range: -40°C to +85°C
  • Storage Temperature Range: -65°C to +150°C
  • Lead Temperature (soldering, 10s): +300°C
  • Soldering Temperature (reflow): +260°C

 

Note: Complete technical details can be found in the MAX4173FESA datasheet at this page’s end.

 

How To Use MAX4173FESA?

The schematics below show the typical application diagram of a MAX4173FESA.

MAX4173FESA Schematics

To measure lower currents more accurately, use a high value for RSENSE. The high value develops a higher sense voltage that reduces offset voltage errors of the internal op amp. In applications monitoring very high currents, RSENSE must be able to dissipate the I2R losses. If the resistor’s rated power dissipation is exceeded, its value may drift or it may fail altogether, causing a differential voltage across the terminals more than the absolute maximum ratings. If ISENSE has a large high-frequency component, minimize the inductance of RSENSE. Wire-wound resistors have the highest inductance, metal-film resistors are somewhat better, and low-inductance metal-film resistors are best suited for these applications. The table below shows the recommended values for the current sense resistor.

FULL-SCALE LOAD CURRENT

ILOAD (A)

CURRENT-SENSE RESISTOR

RSENSE (mΩ)

GAIN

FULL-SCALE OUTPUT VOLTAGE

(FULL-SCALE VSENSE = 100mV)

VOUT (V)

0.1

1000

20

2.0

50

5.0

100

10.0

1

100

20

2.0

50

5.0

100

10.0

5

20

20

2.0

50

5.0

100

10.0

10

10

20

2.0

50

5.0

100

10.0

 

Functional Block Diagram

MAX4173FESA Functional Block Diagram

 

Applications

  • Cell Phones
  • General System/Board-Level Current Monitoring
  • Notebook Computers
  • PA Bias Control
  • Portable Battery-Powered Systems
  • Power-Management Systems
  • Precision Current Sources
  • Smart Battery Packs/Chargers

 

DC Characteristics

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

Operating Voltage Range

V

 

 

 

28

V

Common-Mode Input Range

VCMR

 

0

 

28

V

Common-Mode Rejection

CMR

VRS+ > +2.0V

 

90

 

dB

Supply Current

 

 

 

0.42

1

mA

Leakage Current

0.3

3

µA

Input Bias Current

IRS+

VRS+ > +2.0V

0

 

50

µA

VRS+ ≤ +2.0V

-350

 

50

IRS-

VRS+ > +2.0V

0

 

100

VRS+ ≤ +2.0V

-700

 

100

Full-Scale Sense Voltage

VSENSE

VSENSE = VRS+ - VRS-

 

150

 

mV

Total OUT Voltage Error

 

VSENSE = +100mV, VCC = +12V, VRS+ = +12V

 

±0.5

5.75

%

VSENSE = +100mV, VCC = +12V, VRS+ = +12V,TA = +25°C

 

0.5

3.25

VSENSE = +100mV, VCC = +28V, VRS+ = +28V

 

0.5

5.75

VSENSE = +100mV, VCC = +12V, VRS+ = +0.1V

 

-9

±24

VCC = +12V, VRS+ = +12V, VSENSE = +6.25mV

 

±7.5

 

Out High Voltage

 

MAX4173F, VCC = +7.5V, VRS+ = 28V,VSENSE = 250mV

 

0.8

1.2

V

OUT Low Voltage

VOL

VCC = +5V, VRS+ = 0.89V,VSENSE = 0mV

TA = +25°C

 

1.2

5

mV

 

2D Model and Dimensions

MAX4173FESA 2D Model and Dimensions

Component Datasheet

Related Post



Join 20K+subscribers

We will never spam you.

* indicates required

Be a part of our ever growing community.