Propagation Delay Test

NOTE: This is a work in progress, not meant to be of use to anyone. This circuit is used as a coil driver, with overcurrent protection. As drawn, current limit is about 4A. If the current is exceeded, the driver is shut off until the next rising edge of the command signal.

This is for testing the propagation delays throughout a coil driver circuit. This uses a P-channel Mosfet as the high side driver. The gate is driven by means of an N-channel mosfet. This allows the output to be controlled using standard TTL level signals. The target is to have an end to end delay of less than 1 uS.

Current sensing is done on the high side. There is a current limit set by means of R1. R6 can be used, but with caution - consult the datasheet for the current sense amplifier.

If the current limit is reached, then the output is turned off. The output will be reactivated on the next rising edge of the input signal.

UPDATE August 10, 2021: Assembled board with corrections as outlined in previous updates. The overall delay measures about 200nS.  I used a pot for the current limit, as mentioned on the schematic. I used a through hole resistor for R3 since I forgot to reduce the footprint to a 0805.