Application Hints

The LF147 is an op amp with an internally trimmed input off-

set voltage and JFET input devices (BI-FET II). These JFETs

have large reverse breakdown voltages from gate to source

and drain eliminating the need for clamps across the inputs.

Therefore, large differential input voltages can easily be ac-

commodated without a large increase in input current. The

maximum differential input voltage is independent of the sup-

ply voltages. However, neither of the input voltages should

be allowed to exceed the negative supply as this will cause

large currents to flow which can result in a destroyed unit.

Exceeding the negative common-mode limit on either input

will force the output to a high state, potentially causing a re-

versal of phase to the output. Exceeding the negative

common-mode limit on both inputs will force the amplifier

output to a high state. In neither case does a latch occur

since raising the input back within the common-mode range

again puts the input stage and thus the amplifier in a normal

operating mode.

Small Signal Inverting

DS005647-4

Small Signal Non-Inverting

DS005647-5

Large Signal Inverting

DS005647-6

Large Signal Non-Inverting

DS005647-7

Current Limit (R

DS005647-8

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