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can someone please point me to a good reset circuit design

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Newbie level 6
Feb 22, 2003
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good reset circuit

worry about brownout effects, (real newbie here) so please bear with me. thanks! :)

I think not need to design Maxim and TI have some IC. **broken link removed**

I am not sure exactly what you mean but lets start easy . If you want to reset a batch of logic (cmos / TTL) then I use a simple resistor and capacitor (1 meg .1uf) in series withe the centre point to the reset pins. If you have to start with a low then have the capacitor to ground and of course vice versa.


i really appreciate your responses. i'm trying to reset an HC11 MCU. i remember reading somewhere that a simple resistor/capacitor is not always the right way to go due to poor power supply during power on reset. (i think it's call brown out effect). so i guess i'm looking to design a power good circuit that assures that the power is good and then activates the resistor/capacitor to cause a reset signal. thanks! :)

i'll check out the ic that sebi suggested too. thanks! :)

Supervisor IC


The group of ICs for this are called Supervisor ICs. There is a very large group of them. MAXIM, TI, Linear Technologiy make them.

Some of them even have hardware watchdog circuits so that your processor can never crash. (You can't shutdown those)

For example the following has control options for battery Backed-up RAM gating signals.
If you search manufacturer web sites with "supervisor" keyword you'll find what you need.


edgerate2222 said:
i really appreciate your responses. i'm trying to reset an HC11 MCU.

There are special considerations when dealing with
the 68HC11. Here is a link that should help you sort
this all out.

**broken link removed**

68HC11 with reset - schematic:



Please use this chip to aviode the brown out problem

ds1810 made by dallas semiconductor now dallas is merge with maxim semiconductor you can ask for sample chip from maxim they provide atleast 2 sample



there will be two types of reset ckt is ther
1.reset on low
2.reset on high

which one do u want

For more infom, if you want a discrete way, look at following microhip app note.

**broken link removed**

If you want simplest method. A simple 3 pin reset IC will have a protection from brownout. I normally use Zetex ZXCM serie. :idea:

I know that any supervisory IC no have PULSE STRETCHING, and I just i have found this V6340.

If someone know other IC without pulse stretching......

MC33xxx and MC34xxx from ON Semiconductor

thanks for answer, but MC34064 turn off just at 4.3V when hte power supply is 5V.

My application need turn off at 3V when the power supply is 5V. Minimum voltage acceptable for uC is 2.7V.

After to test various discrete circuits, the best opcion are Supervisory IC, but they have a pulse stretching (no all).

I have one V6340 and work OK.

exists another IC like v6340?

There's a good selection of easy reset chip out there

...but please consider MAX809 or MAX810 from.... PHILIPS Semi.!!! YES - sounds like a MAXIM, but these are Dutch chips :p
Costs ~0.25euro, so this is peanut comparing sleepless nights of wondering does it hang up, or not (of course after delivery to customer).
And last but not least: it needs NO EXTERNAL components. Housed in small, nice SOT-23.

Watch the attachement for full specs (Vtreshold, output polarization etc.)


try tl7705 it is a good reset circuit or max7705 as it need no external components
good luck

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