LM2903 Comparator output oscillates


I am using an LM2903 Comparator on my design to measure sensor signal. Constant current source is provided to the sensor by means of resistors (connected to 2.5V). I have an RC input filter (R=1K,C=0.47u) at the non inverting input of the comparator followed by R1=1k (input resistor) and RF=475k (feedback resistor) for external hysteresis. Reference voltage is 1.25V.
When I tested the circuit, I found my comparator output oscillates instead of saturating. So I put small cap (10nF) across the feedback resistor. Now the output bounces from high to low and vice versa even though my sensor input is constant.

Best Answer

An LM2903 is an open collector device, you need a pull-up on the output. Also, the LM2903 Vcc must account for headroom, so it probably needs at least 3.3V if not 5V power.