Skip to datasheet
Dual voltage comparator

LM2903 Basic Circuit

Build a basic LM2903 circuit with labeled pins, component values and connection guidance.

Package view

LM2903 in a circuit

A physical IC, a resistor reference and a clearly defined output.

LM2903P pin 8 uses 5 V, pin 4 ground and 100 nF bypass. A 30 kΩ and 20 kΩ divider produces 2 V at pin 2. VIN drives pin 3. A 10 kΩ pull-up on pin 1 supplies the HIGH output. Unused channel pin 5 is ground, pin 6 VREF and pin 7 unconnected.
Same-name labels are connected. All ground symbols share one return. Meter input is high impedance.

Connect it, step by step

Follow the component values and pin connections

Build the reference

30 kΩ above and 20 kΩ below produce a nominal 2 V reference from 5 V.

Compare VIN

Connect the measured voltage to IN1+ and VREF to IN1−. VIN below 2 V makes OUT1 LOW.

Add the pull-up

Connect 10 kΩ from OUT1 to 5 V. Without it, the released output is floating rather than HIGH.

Component view