Freekout lt1054 getting hot

[gaffled]

Quick question, when I plug in my power supply(Dunlop 18v) the lt1054 immediately start getting hot.  I looked for solder bridges and the like but found nothing.  My voltages on the reg and lt1054 look good, not quite sure why this would start getting so hot.  Thanks, mike

[EBRAddict]

I would pull all the ICs other than the LT1054 and vreg and check the temp again. Then add them back one at a time and see if it heats up. I'd start with the cheapest chips first

[daleykd]

Should the LT1054 be getting 18V?

[EBRAddict]

Should the LT1054 be getting 18V?

That was my first answer, then I looked at the schem and the input is feeding a 15VDC linear regulator. 15V is the listed max operating voltage for the LT1054.

[daleykd]

Should the LT1054 be getting 18V?

That was my first answer, then I looked at the schem and the input is feeding a 15VDC linear regulator. 15V is the listed max operating voltage for the LT1054.

HAHAHAHA.  I say "Freekout" and thought the OP meant he was freaking out because it was hot. 

[midwayfair]

15V is the listed max operating voltage for the LT1054.

There's your problem.

[gaffled]

When I get back home I'll trying pulling all the other ics and test it again.  When I checked the voltages the lt1054 was seeing around 14.77 I believe so the regulator was doing its job.  I checked that first to make sure the lt1054 wasn't seeing 18 volts, but maybe I'll check again just to make sure.  Won't be able check till tomorrow though.  Thanks for the input, mike.

[gaffled]

Ok narrowed it down to the ad633.  When I put this in the lt1054 gets hot.  I assume I got a bad one from China.   Can anyone tell me why this chip would make the LT1054 get hot.  Thanks, Mike

[EBRAddict]

Check your pin voltages on that socket, post them here, maybe someone can take a look. I'm not familiar with it. Datasheet says it's a "low cost" analog multiplier at $10 a chip

[John S]

I'm having the same issue with the lt1054 in my rust bucket project. I took out all the chips and it was still really hot. When I measure the voltages on the l7815 cv it reads 18v on the in and it jumps around on the out pin. I tried several l7815cv (socketed) and they all do this. I've even tried several lt1054 chips and they all get hot. Any suggestions. Thanks

[lincolnic]

I'm having the same issue with the lt1054 in my rust bucket project. I took out all the chips and it was still really hot. When I measure the voltages on the l7815 cv it reads 18v on the in and it jumps around on the out pin. I tried several l7815cv (socketed) and they all do this. I've even tried several lt1054 chips and they all get hot. Any suggestions. Thanks

If the voltage is jumping around on your output pin, something is wrong. The regulator should be putting out a steady 15V. That's the only job it does.

[John S]

I'm using a L7815CV instead of a LM7815. Would that matter? Any suggestions as to what could be wrong?

[jimilee]

Did you check the pin out?


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[EBRAddict]

Are you guys using low-ESR filtering caps on your LM7815? If so refer to the datasheet because I think they need electrolytic caps with "regular" ESR.

[madbean]

I seem to remember people having trouble using the L7815 in some builds in the past, but I think the threads got nuked in the forum crash. I'd stick to LM7815. I probably have an extra I can send you if it helps.