ZXCT1020 View Datasheet(PDF) - Diodes Incorporated.

Part Name

Description

Manufacturer

ZXCT1020

Low offset current output current monitor

Diodes Incorporated. 

ZXCT1020

Application information

The ZXCT1020 has a VB pin that is used to provide power to the current monitor. The maximum

voltage applied to the ZXCT1020 must be applied to this pin. The S+ and S- pins are used to

measure the current flowing to the load through the sense resistor. In normal use, the S+ is tied

to VB via a shunt resistor, RH making the ZXCT1020 essentially line powered.

The ZXCT1020 has a programmable gain set by the ratio of two external resistors RG and RSH.

RSH

S+ 1

VOUT

3

RG

RS

IL

VB

S-

(LOAD)

4

5

-

+

2 ZXCT1020

GND

RSH sets the transconductance whereas RG set the gain and results in an output voltage defined

as:

VOUT

=

--R----G----

RSH

×

VSENSE

Where VSENSE = RSENSE x IL

The ZXCT1020 has been tested to the same conditions as the ZXCT1021 giving an overall voltage

gain of 10. The gain of the ZXCT1020 can be adjusted simply by varying RG. So to achieve a gain

of 50 RG is increased from 15k⍀ to 75k⍀. An alternative is to decrease RSH from 1.5k⍀ to 300⍀.

Decreasing RSH increases the transconductance and, if for any given gain, reducing the RSH will

reduce the overall output impedance.

To achieve a gain of 100, for example, the following resistor values could be used:

RSH = 150 RG = 15k

Issue 1 - August 2007

11

© Zetex Semiconductors plc 2007

www.zetex.com

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