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PSoC 5, 3 & 1 MCU

Anonymous
Not applicable

This is probably basic stuff but Cypress Technical Support asked me to post it on the forum. I was attempting to make a charge controller for a solar panel and a 12 volt sealed lead acid battery. For measuring the battery's current I used a 0.01 Ohm shunt resistor and for voltage I used a voltage divider. I tested each separately with the PSoC 5LP and they worked as expected but when I tried to connect both at the same time the PSoC "blew up." Initially I thought it exploded due to a difference in voltage potential because the PSoC 5LP was being powered by a laptop at the time. However, I attempted to connect the circuit again with the PSoC unplugged from the laptop (PSoC was dead at this point, anyhow) and it released more smoke. Could there be some sort of internal short on the board itself? I would like to avoid this sort of thing in the future, so any help is greatly appreciated. Thank you.

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Honored Contributor II

PSoC pins max voltage limit is about 5.5V, the schematic shows at least two (current sensing) pins sitting at 12 V, here is the result. You must use either high-side current sensing amplifier (such as MAX4172), or move current sensing resistor to the ground plane 

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8 Replies
Honored Contributor II

PSoC pins max voltage limit is about 5.5V, the schematic shows at least two (current sensing) pins sitting at 12 V, here is the result. You must use either high-side current sensing amplifier (such as MAX4172), or move current sensing resistor to the ground plane 

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New Contributor

ACS758 might also be a viable option.

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Honored Contributor II

How are you powering the PSoc 5 lp? Also I didn't see your shunt resistor in the pictures.  When you are using a large battery your wires and shunt resistors should be large.  Also I would look for a negative voltage reaching the PSOC 5lp . What kind of charger are you using and what are the Spec's. Get a Scope and check for noise and ripple on the 12 volt  lines. Check the setup with a Voltmeter and make sure the voltages are within range. 

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Honored Contributor II

One other thing use a Star ground method to remove ground loops.

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Honored Contributor II

I agree with the others that you need to look into a sensor chip that is made to interface the Battery information.  However I think this is a grounding issue as I stated in Post #4.  The reason is because it worked before you tried to combine them into one circuit.

Valued Contributor II

Possible cause (simplified)

   

Anonymous
Not applicable

I greatly appreciate everyone's responses, they are all very helpful. I have included a stock image of the shunt resistor from Amazon. When completed the microcontroller will be powered by the 12-volt battery via a step-down buck converter. The charging of the battery will be done with PWM and P-MOSFETs. I wanted to try to use a shunt resistor instead of a Hall effect sensor because I had not used one before. I am fairly sure it was the low-side of the 20k Ohm resistor that I was attempting to connect to the PSoC when the short occurred. When/if I try it again I will move the shunt resistor to the low-side of the battery. Thanks!

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Esteemed Contributor II

The barbecue  season is open now!   😉

   

 

   

Bob

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