I have a new board based on CY8C5468AXI-LP106 device. After 10-20 minutes the chip gets hot and the power consumption in the external power supply goes from a few mA to hundred of mA and chip gets hot. During this time I can program and debug the board using miniprog3.
I have revised the schematic and checked symbols and footprints of all components and do not see any thing wrong.
I attache schematic and some screenshots of the PSOC Creator if you want to have a look. On the Schematic, FILA_X are digital outputs, and COL_X are analogue inputs going to an internal AMUX/ADC. The Power supply is 9V and with two regulators goes down to 5V and 3V3.
Could you please have a look and check if there is anything wrong? have anyone an idea what can be the problem?
Thanks in advance,
Solved! Go to Solution.
You are going to need to provide the power and ground plane files from you gerber. That is the only way we maybe able to help you. Also I see some led being driven I hope you have current limiting resistors for them and also what about your voltage regulators I don't see any noise filter capacitors in your schematic.
One more issue I forgot to cover the chips could be affected by ESD are you using proper ESD methods in your assembly process. Are you assembling the boards or do you have an external vendor? Is your work space ESD compliant ?
Thank you very much for your support.
Board is 6 layer, so I am sending you the top layer with some nets highlighted. If you want I can send you other layers but may be is confussing.
Yes, leds have limiting resistors of 330 Ohmios (green leds, VF= 3 Volts). I am sending also the Power supply generation schematic if you want to have a look.
I would understand any problem with ESD for just one board, but the same happens with three boards. I have five boards in total and tested three which have burnt out. The other two still havent been tested, I am wainting to find the problem before.
I am sending you some part of the schematic of PSOC Creator in case you see any problem with the ADC/MUX , which is basically what is inside PSOC.
Thanks in advance,
I had a similar problem in LP35.
contact Vssa (64) was not connected to the ground.
I could not find it on time in the tester. it is connected inside the crystal.
Without this connection, the chip heats up.
Thanks for your answer.
Not sure If I understand you.
In my schematic VSSA (pin 64) is conected to GND_A (analog ground) and this is conected to GND (digital ground) using a ferrite bead, so should I replace the ferrite bead for a 0 Ohms resistor? is this what you propose?
No. Just check the contact. In my device, I forgot to install a jumper and VSSA remained unconnected.
Run your project on another device (for example CY8CKIT - 050 PSoC5_LP). If the chip does not heat up, the problem is in the board.
Probably there is an input signal above 5 volts which heats the protective diodes.
Looking at your Schematic I didn't see the Power bypass Capacitors and it appears from your Gerber there maybe some issues with the layout of the power supply pins. I am sending you some pictures on this layout for you to check.
Maybe just an unqualified sidekick:
You have about 7 resistors with 30 Ohm which can give you further hints about current consumption.
Why dont you measure the voltage over all those resistors? Maybe you have luck:)
Ok, thank you, nice idea.
Anyway, I start to think now, the problem is not in the PSOC but on the board. I am checking all symbols, footprints, and components on the board itself (checking correct orientation, shorts, ). Working on it...lets you know as soon as I get something.
After some time finding out the problem I have concluded that the problem came from the inputs to the analog MUX-OA-ADC (see Creator-ADC-schematic.png above).On start-up all signals getting into this inputs were about 3V. When I set this inputs to be under 2 V my systems works well.
VDDA for my boards is 5V.
ADC range is 0-2.048V. Maybe a 3V signals on the ADC input with range 0-2.048 can cuase the problem.
Thansk again for your support an hope this can help someone.
No, inputs are allowed to go up to Vdda, regardless of the ADC input range. The latter only leads to getting an overflow.
But could you run into a situation where the inputs were higher than Vdda during startup? If yes, than this could lead to the PSoCs failure.