LM358 pins: a dual op-amp

Everywhere in chargers, sensor boards and current sensing. The rule: in an op-amp with feedback, the two inputs are almost equal. Tap a pin.

Where you'll meet it Battery chargers, sensor boards, current sensing, simple amplifiers (similar: LM2904, the quad LM324)

Drive outputControl / signalGroundSupply

Pin 1 · Drive output

OUT A

Output of op-amp A.

🔧 How to measure

DC to GND.

Expected on a working boardDepends on the circuit; with a single supply, between 0 and VCC−1.5 V

On the scope

⚠ If the reading is wrongIf the output is stuck high or low while the inputs are right, the IC may be faulty.

📋 What order to measure in?

Are VCC (8) and GND (4) present?
Rule: in an op-amp with feedback, the − and + inputs are almost equal. A big difference means the output is pinned high or low.
If used as a comparator (common in chargers): output HIGH when + is above −.

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Go further

Course: getting to know the op-amp