Re: Initializing a Flip-Flop on Power-up
- From: Joerg <notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx>
- Date: Fri, 17 Feb 2006 18:22:20 GMT
Hello Spehro,
While you can use an RC (typically about 0.1s time constant with a
diode to help out the protection diode to Vdd, a series resistor to
limit the current in case of a Vdd-to-ground short, and perhaps a
drain resistor from Vdd to Vss to make sure that Vdd falls reasonably
quickly), it's far from foolproof, more complex and not much cheaper. Another low-cost solution is to use a zener, a BJT and a few
resistors, with or without the RC, but that consumes more power, and
is even more complex.
My circuit du jour is a BSS123. Drain tugs on input that needs reset low. Gate has cap to VCC and resistor to GND. Plus discharge path if some BOR is required as well. If the 4-5c are too much I'll sometimes use a BJT. There must be a discharge path from VCC to GND if power is turned off. If there isn't that needs some extra parts.
Regards, Joerg
http://www.analogconsultants.com
.
- Follow-Ups:
- Re: Initializing a Flip-Flop on Power-up
- From: Frank Bemelman
- Re: Initializing a Flip-Flop on Power-up
- From: Rich Grise
- Re: Initializing a Flip-Flop on Power-up
- References:
- Initializing a Flip-Flop on Power-up
- From: Dan Charette
- Re: Initializing a Flip-Flop on Power-up
- From: Spehro Pefhany
- Initializing a Flip-Flop on Power-up
- Prev by Date: Need schematic inverter
- Next by Date: Re: IGBTs are pretty fast
- Previous by thread: Re: Initializing a Flip-Flop on Power-up
- Next by thread: Re: Initializing a Flip-Flop on Power-up
- Index(es):
Relevant Pages
|
