MAX9923T(2009) Ver la hoja de datos (PDF) - Maxim Integrated

Número de pieza

componentes Descripción

Fabricante

MAX9923T
(Rev.:2009)

Ultra-Precision, High-Side Current-Sense Amplifiers

Maxim Integrated 

Ultra-Precision, High-Side

Current-Sense Amplifiers

Functional Diagrams

1

RSB

2

RS+

3

RS-

4

N.C.

5

GND

MAX9922

( )R2

GAIN = 1 + R1

10

VDD

1

RSB

9

OUT

R2

8

FB

R1

7

REF

2

RS+

3

RS-

4

N.C.

6

SHDN

5

GND

MAX9923

MAX9923

VERSION GAIN

T

25

H

100

F

250

10

VDD

9

OUT

R2

8

FB

R1

7

REF

6

SHDN

Detailed Description

The MAX9922/MAX9923 high-side, current-sense

amplifiers implement a patented spread-spectrum

autozeroing technique that minimizes the input offset

error, offset drift over time and temperature, and the

effect of 1/f noise. This technique achieves less than

25µV (max) offset voltage.

The MAX9922/MAX9923 high-side current-sense ampli-

fiers feature a +1.9V to +28V input common-mode

range that is independent of supply voltage (VDD). This

feature allows the monitoring of current out of a battery

as low as +1.9V and enables high-side current sensing

at voltages greater than the supply voltage.

The MAX9922/MAX9923 monitor current through a cur-

rent-sense resistor and amplify the voltage across the

resistor. The 28V input common-mode voltage (VRS+)

range of the MAX9922/MAX9923 is independent of the

supply voltage (VDD). High-side current monitoring

does not interfere with the ground path of the load

being measured, making the MAX9922/MAX9923 par-

ticularly useful in a wide range of high-voltage systems.

The MAX9922/MAX9923 use Maxim’s patented indirect

current feedback achitecture. This architecture con-

verts the differential input voltage signal to a current

through an input transconductance stage. An output

transconductance stage converts a portion of the output

voltage (equal to the output voltage divided by the

gain) into another precision current. These two currents

are subtracted and the result is fed to a loop amplifier

with sufficient gain to minimize errors (see the

Functional Diagrams.)

Battery-powered systems require a precise bidirection-

al current-sense amplifier to accurately monitor the bat-

tery’s charge and discharge currents. Measurements of

OUT with respect to VREF yield a positive and negative

voltage during charge and discharge cycles (Figure 1).

The MAX9922 allows adjustable gain with a pair of exter-

nal resistors between OUT, FB, and REF. The MAX9923T/

MAX9923H/MAX9923F use laser-trimmed internal resis-

tors for fixed gains of 25, 100, and 250, respectively, with

0.5% gain accuracy (see the Functional Diagrams.)

10 ______________________________________________________________________________________

Share Link: