MP8110 datasheet(4/10 Pages) MPS

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MP8110 – PRECISION HIGH-SIDE CURRENT-SENSE AMPLIFIER

MP8110 Rev. 0.9

www.MonolithicPower.com

9/21/2007

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

OPERATION

The MP8110 is a current-sense amplifier with a

wide operating input voltage range of 2.5V to

40V.It has 1.4V to 40V Common-Mode range.

This feature allows the monitoring of current

flow out of a battery in deep discharge, and also

enables high-side current sensing up to the

supply voltage, VCC. Current flows through the

sense resistor, RS, which generates a sense

voltage VRS. The high precision sense amplifier

built into the MP8110 monitors the differential

voltage across RS and dynamically adjusts the

gate voltage of the internal P-channel MOSFET

to maintain a equal passing current as IRG1. The

current amplifier gain is therefore set as: RGS /

RG1.

Choosing Sensing Resistor

Given the gain and maximum load current,

select RS such that VRS does not exceed

+0.25V and VOUT1 does not exceed 5V. To

measure lower currents more accurately, use a

high value for Rs. A higher value develops a

higher sense voltage, which overcomes offset

voltage errors of the internal current amplifier.

In applications of monitoring very high current,

ensure RS is able to dissipate its own I

losses. If the resistor rating power is exceeded,

its value may drift or it may fail altogether,

causing a differential voltage across the

terminals in excess of the absolute maximum

range (0.25V).

MP8110 Datasheet(PDF) 4 Page - Monolithic Power Systems