problem regarding vdd

sid

i am using pbasic2 ic ie pic16c57c. the ic was working fine and i made a micromouse with it.

But suddenly one day when i started it , the vdd was comming 3.4v and when i removed the basic stamp ic. i get same 5v from the 7805.
And as soon as i attach the ic to the circuit the 7805 starts delivering 3.4v.

what is the problem please help soon?

Jon Williams

Check your connections very carefully -- sounds like you've got a short that is causing the circuit to draw too much current and making the regulator output sag.

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Jon Williams
Applications Engineer, Parallax

sid

i took out the ic from the ckt and applied vdd and ground to the ic seprately. the 7805 output again became 3.4v. i have also replaced the 7805 with new one.but the problem persists.
what happened?

Clock Loop

Could your power supply to the 5 volt regulator be bad. Does the 7805 get hot? (even warm) then you most definetly have something drawing too much current.

If your regulator doesn't get hot, then your power supply sounds like its not providing enough, are you providing at least 1.5 volts more than 5 volts? In other words are you providing at least 6.5volts to your voltage regulator? Check all your connections.

sid

my 7805 becomes warm and the basic stamp becomes hot very soon. and when i attach it with serial port it gives eeprom verify failed.

Clock Loop

stop powering it, that is all wrong, nothing should get even warm, you need to triple check all your connections, if you have run your circuit for days allowing the stamp to get hot, then you probably already fried it.

Clock Loop

do you have anything hooked up to the outputs of the BS2? I would suggest starting over at square one. disconnect EVERYTHING, only wire up what NEEDS to be wired to allow the stamp to communicate with the PC, and what is required to make the stamp work, if it still gets hot, you have a wiring problem and / or your stamp is already toast.

does it get hot when you DONT have it hooked up to the serial port?

sid

yes it get hot even it is not connected to serial port .but when i run the program it detects the basic stamp 1.0v and showa eeprom verify failure where as the eeprom is doesnot gets hot and if i seprately supplies power to eprom it shows 5v. may the basic stamp is halfly roasted. what do u say.

Clock Loop

you said "i took out the ic from the ckt and applied vdd and ground to the ic seprately."

Do you mean you powered the pic16c57c chip with NOTHING but +5V and GND connected and it gets hot/draws too much current?

That again sounds like your circuit wiring is bad, something in your circuit caused the pic16c57c to fry.

Ive had different kinds of IC chips fry on me, and when they do, they either don't work and don't heat up, or they heat up like mad and still don't work. Some smoke, some work for a while at seriously hot temperatures and then Smile out, some just die without a wimper.

Almost all IC's will NOT get hot if they are wired and working properly.
A good method of electronic design is the finger test. TAP your chip with your finger as soon as you power it, keep tapping it to see if it gets hot, if it starts to feel warm or hot, then quickly turn it off, because something is wrong.

I have had that method save my IC's many times. Its not GOOD for your IC's but at least it still might work after you fix the wiring problem.





It kinda sounds to me like you fried your pic16c57c. If you can't even provide 5v and GND without it getting hot, while its not connected to anything, then its most def fried. (im talking power the pic16c57c ALONE, no EEPROM, nothing)

Most IC's will just SIT there when you connect GND and 5V. They shouldnt get hot, or even warm.

Before you go out and replace it, you need to go over your circuit and figure out why it fried. Because you will just fry another.

Post Edited (BPM) : 11/27/2005 5:09:19 PM GMT

sid

ya, i also thinks that it is fried. i am checking my ckt again. for bad wiring.