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can someone please point me to a good reset circuit design

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edgerate2222

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good reset circuit

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

barrybear

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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.

Barrybear
 

edgerate2222

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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! :)
 

zoovy

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Supervisor IC

edgerate2222,

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.
http://www.linear.com/prod/datasheet.html?datasheet=321
If you search manufacturer web sites with "supervisor" keyword you'll find what you need.

Zoovy
 

ME

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68HC11 with reset - schematic:
 

Fragrance

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RESET PROBLEM

FRIEND

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

regards
khalid
 

senthilkumar

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hi,

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

which one do u want
 

SFIO

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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......
 

jzo777n

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MC33xxx and MC34xxx from ON Semiconductor
 

SFIO

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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?
 

jarod

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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.)

:wink:
Cheers,
Pauli
 

mzewani

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

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