Is there a relatively simple circuit which can assert a power-on reset. In other words, the line will go high briefly at power-on and then switch low and remain that way until power-off. Any ideas would be appreciated. --dbernat32
How does a spare inverter gate, plus an R, a C, and a diode sound? (View in fixed font or M$ Notepad): ` VCC VCC ` + + ` | | ` .-. | ` R| | - D ` | | ^ 1/6 74HC14 ` '-' | ` | | |\ Reset Pulse ` o----o-----|H>O----o ` | |/ ` C--- ` --- ` | ` | ` === ` GND created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de Positive going pulse width (one and only one pulse at turn-on) will be a little less than R*C seconds. The schottky diode is actually optional if you have a linear supply that discharges slowly at turn-off. This is just about the simplest reset pulse you can get. Remember that this requires a gate with schmitt trigger input hysteresis to get a clean reset pulse at turn-on. If you've got a spare NAND gate on board, try using a 4093 schmitt trigger NAND gate instead of a standard NAND gate IC. But if a reset pulse with slow fall time is OK, you can just use any inverter gate (or a NAND or NOR set up as an inverter). If this doesn't do the job, describe your requirements. There are many power watchdog/monitor ICs that can do the job for you with equal simplicity (although they cost more). Do you need brownout protection, too (reset asserted if power supply goes below a certain voltage)? If so, one of these ICs or a comparator would be a better choice. Good luck Chris
