ZXCT1011 datasheet(6/8 Pages) ZETEX

Numer części	ZXCT1011

Szczegółowy opis	High-side low drift current monitor

PDF	8 Pages

Scroll/Zoom	100%

Producent	ZETEX [Zetex Semiconductors]

Strona internetowa	http://www.diodes.com/

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6 / 8 page

ZXCT1011

Issue 1- July 2005

www.zetex.com

A 1 ampere load current is to be measured into a battery. The output signal required to an over

current controller needs to be 3.3V. What is a suitable value of Rout and what will the error due

to the supply current be?

Vin = 5.0V - 9.0V

Iload = 1.0A

Output signal required: 3.3V

Figure 1

ZXCT1011 to measure a 1.0 A load current

To obtain the highest accuracy, choose the of Rsense to give 100mV:

Rsense = 0.1/1.0 = 0.1

The transconductance using a 120

resistor will be 10mA/V.

Choose Rout to give Vout = 3.3V, when Vsense = 100mV

Rearranging equation 1 without the offset error gives:

Rout = (Vout x Rshunt) / (1.2 x ILoad x Rsense)

Rout = 3.3k

Now consider the offset error for this resistor:

Offset due to supply current = Rout x 4x10

-6µA = 13.2mV = 0.4%

Vsense+

ZXCT

1011

sense-

Vin

R sense

Iload = 1A

I out

Rshunt

out

Rload

Rshunt

120R

3.3V

= 5.0V - 9.0V

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