Data Sheet

LT9890

THEORY OF OPERATION

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Rev. 0 | 8 of 11

Figure 15 shows a typical LT9890 application. An input current up to

150 A flows from the IP pin to the IM pin through an internal copper

RS. The open-loop gain of the amplifier drives the negative terminal

voltage to the positive terminal voltage, making the current through

the RG proportional to the input current. This current becomes

ground-referenced after flowing through the output p-channel met-

al-oxide semiconductor (PMOS) device. An internal algorithm with

factory trim corrects for the copper-sense element nonidealities.

The internal negative regulator forces the same supply voltage

across the amplifier through the entire 2.7 V to 65 V voltage range,

creating excellent common-mode rejection. All internal circuitry runs

off the input rail. The small-supply current relative to the large-signal

current has an insignificant effect on the TUE.

Figure 15. Typical Application