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Hello,
I am doing the simulation in LTspice. With the same circuit, I see something wrong with the output of LM2903B. May I ask for some help? Either my circuit is wrong or the model itself is not correct.
Vcc=5V Vin: 5V PWM
Thank you,
Alice
Hello Alice,
Actually, it is working as expected.
For the newer models (LM2903B), when a specification is exceeded, such as supply voltage or input voltage, the output is forced to 1/2 the supply voltage to indicate an error.
The maximum input voltage for the LM2903 family is Vcc-2V, or 3V on a 5V supply.
You must be applying more than 3V to one of the inputs (assuming a 5V Vcc).
Please see the LM339 family appnote, section 2:
Application Design Guidelines for LM339, LM393, TL331 Family Comparators
Reduce the input below 3V and the output should function as expected. The actual device will NOT go to 1/2 supply.