cancel
Showing results for 
Search instead for 
Did you mean: 

startup reset

bleumers_j
Associate II
Posted on December 08, 2003 at 11:40

startup reset

7 REPLIES 7
bleumers_j
Associate II
Posted on November 28, 2003 at 09:36

Hi,

Sometimes my st7lite29 application doesn't start when i switch on the power. When i add a reset network (1µF cap to gound and 100 kohm to +5V) it works fine any time.

It is absolutely no problem for me to add those two components, but i seem to be the only one who has to do this. Maybe i'm doing something wrong... Ex. is it necessary to switch on the LVD?

Greets.
delser9
Associate II
Posted on November 28, 2003 at 10:12

Hello joble

according to datasheet p112, it is indeed necessary to use LVD, or a reset circuit. You are not the only one who does need it.
bleumers_j
Associate II
Posted on December 02, 2003 at 09:35

What is the best solution, the LVD or the external RC-network?

The external RC seems to me the most reliable.

jatin
Associate II
Posted on December 02, 2003 at 12:40

Incase you use internal reset circuit(LVD), you will have to connnect 0.01 uf capacitor between GND and the reset pin.

delser9
Associate II
Posted on December 03, 2003 at 03:01

I have done it with LVD, and it works fine! I never tried a reset-circuit because it is more expensive than LVD, and I never had any problem with the reliability of the LVD.

bleumers_j
Associate II
Posted on December 08, 2003 at 09:22

Ok, the LVD is totaly clear to me now. I'm going to remove the rc and use the lvd.

Just one more question: Is it ok to use the highest treshold voltage (4.1V) for a 5V supply. I suppose it is, but just want to be sure.

Thanks!
delser9
Associate II
Posted on December 08, 2003 at 11:40

Yes, it is if you have a normaly filtered power supply. Maybe you should also use the AVD to safely shut down the mcu (depends on your application), before it is internally reset.