LM293A: overdrive

Eric(Dongguan) Zhu

Part Number: LM293A
Other Parts Discussed in Thread: LM293, LM2903B

Questions about the comparator LM293ADR, please help to answer.
1. There are two test conditions for response time in the specification. What is the main difference? Why is the time difference so big?
2. Does Overdrive mean overshoot? Or overloaded?
3. When used as hardware overcurrent protection of PFC (requires 1-2us reversal), which test method should be referred to?

4. When used for hardware overcurrent, replace LM293 with other general-purpose comparators, will it affect the protection current value? As shown below

over 1 year ago

0 Paul Grohe over 1 year ago

TI__Mastermind 49946 points

Hello Eric,

Overdrive is the amount of voltage PAST the trip point.

Comparators will speed up as you drive them harder. 5mV is considered a very small amount, and it is expected that the comparator will be the slowest.The "TTL" test is almost 5V of overdrive, so it is as fast as it can be.

Usually after 100mV overdrive, it becomes diminishing returns. See the LM2903B prop delay curves as an example: