Connection was: Battery+: Motor+ and 7805 regulator for PIC. Battery-: FET-Source and regulator for PIC. FET-drain was connected to Motor- *and* analog comparator input. (but comparator disabled!) The current was "sunk" through the motor and into my +5v line from the 7805 regulator. The voltage-potential over the motor was thus less than 3v as I actually only had 6 Ni-MH cells to draw from. Motor was a very high-ohm cd-rom motor (head-movement) that I had ripped from a dead 4x. Thus, I'm not all that concerned with the clamp as it didn't get all that much abuse. I hadn't considered that the port had such clamping and that the comparator input doesn't like voltages abowe Vdd. (I thought it was a more like an op-amp type comparator...) I still need to clamp it somehow... Maby a little 5.1v zener? More than 5.1v and it conducts! By leading it through a resistor it would drop voltage to required level. KreAture ----- Original Message ----- From: "Olin Lathrop" To: Sent: Sunday, June 22, 2003 9:14 PM Subject: Re: [PIC]: Behaviour of PIC16F62x with over-voltage on comparator? > Kyrre Aalerud wrote: > >>> If I send 10 volts in one of the comparator inputs of a 16F62x, will > >>> it work and clamp it to VDD? > >> > >> If it did, it wouldn't be 10V. 10V is way above the absolute maximum > >> rating for those inputs, so you should expect it to cause serious > >> damage. > >> > >>> Will it allow a current to flow or will it still be high impedance? > >> > >> Probably lots of current for a short time. No guarantees after that. > > > > It didn't cause damage, but the pin did conduct. About 25mA wendt > > through. The port is fine and everything seems to work as usual. > > You are seriously trying to tell me that you held the pin at 10V with Vdd > at 5V and it only drew 25mA with no damage!!? Something in this statement > is clearly incorrect, considering how an undamaged PIC has a diode from > the pin to Vdd. > > I'm guessing that the 10V wasn't. This could be explained if you're 10V > really had 180ohm or so in series with it. Of course that means the 10V > claim is incorrect because the PIC pin will have only been 700mV or so > above Vdd. > > > ***************************************************************** > Embed Inc, embedded system specialists in Littleton Massachusetts > (978) 742-9014, http://www.embedinc.com > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.