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Design circuit with CY8C3866AXI-040 | Cypress Semiconductor

Design circuit with CY8C3866AXI-040

Summary: 3 Replies, Latest post by danaaknight on 12 Aug 2013 05:12 AM PDT
Verified Answers: 0
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user_253382995's picture
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I designed new circuit using CY8C3866AXI-040. Due to an error, when trying to install the program chip can not be found. I followed the rules of the circuit design psoc3 but chip can't be found. Then I searched for the error. I found that  VDDD voltage> VDDA voltage. I measuered VDDD voltage 0.7 V. VDDA voltage is 5.2 V. So chip can't be found. When I equal to voltages with jumpers. IC quickly is heating. I could not find the cause of warming. I attach design file. Can you look at design. When VDDD = VDDA , what is the cause of warming  of IC. Thanks.

user_253382995's picture
28 posts
user_119377051's picture
866 posts

Hi yılmaz

I can't figured out the cause of ploblem from picture of board and schematic.

I guess, does some pins that has a voltage was grounded?

Vddd is doubtful I think.

user_14586677's picture
7646 posts

If chip is getting hot most common problem is latchup, some thoughts -


1) Latchup occurs when a pin is taken outside power supply voltage, eg.

Vssd,Vssa > pin or pin >  Vddd, Vdda. Then chip internally has a parasitic SCR

trigger shorting Vdd to Vss, and draws a lot of current obviously.


Question, chip getting hot immeadiatley, power supply showing high currents

immeadiately, or after CPU well into code ? Code your processor to just start,

but do nothing, sit in a loop immeadiately, right after startup. If Idd does not jump

to latchup condition then power system probably OK. Then suspect processor

GPIO triggering some load causing a transient on a pin outside supply rails.


2) You have a relay, I cannot see drive coil on schematic, I assume Q1 is driving it

and D50 is strapped across coil to suppress turnoff transients ? Check Q1 collector

with scope, to see it never transients outside Vddd, Vdda or < Vssd,a. Set scope

up to trigger on 5.5 initially, then - .5, to see if you ever get a transient outside power

supply rails. If your scope has deep memory trigger off init of power supply and look

at each pin (tedious) to see if you can qualify a trigger outside supplie rails.


3) Look at ground points around board, trigger off  main ground reference , -.5, to

see if you can get a trigger. This is difficult as you would need to cycle power each time

you look at a new pin.


Some thoughts, Dana.

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