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TPS630250: Output polarity reversing and Vfb amplifier

Prodigy 40 points

Replies: 4

Views: 120

Part Number: TPS630250

Hi All,

I am trying to use TPS630250 to drive two leds alternately. Drive current is 1A for one and 0.1A for the other. To minimize the loss at Rsns I have used a current sens amplifier so I can use a smaller Rsns. Also to be able to switch between leds with only two electrical connections I have paralleled them at reverse polarities to each other and used a H-bridge to change the current direction. My plan was one of the leds would be reverse biased while the other is conducting. Led's max reverse voltage specs are 5V, and Vf are about 3.3V at my current levels so I thought there would be no problem.   

The amplifier seems to be working as it should. The H-bridge and paralleled leds are also working as long as I don't try to change polarity. However when I change the polarity the TPS630250 fails. After failure L2 pin becomes short circuit to GND of the chip.

I have tried to first shutdown the device and then change polarity but result seems to be same. Thanks in advance to anyone who can help.

Best Regards

Batur 

  • Hi Again,

    Can this be possible because TPS630250 lacks open circuit protection?? I can add a zener in paralell to H-bridge maybe? 

    Best Regards

    Batur

  • In reply to user4757768:

    Dear User: 

    May you give me more detail information about the U2? It's unclear in the graph, and hard for me to analysis the system.

    In my opinion, it's easier to debug after locate the issue. So, may you help to check the issue position?

    I'll recommend:

    1. Remove U2 and surround parts, replaced with a resistance. To check if the power rail work well.

    2. Remove the buck-boost converter, replaced with a current power supply, to check if the load work well. 

    Besides, where is the H bridge? Is it integrated inside U2? It's appreciate if you could show the system much clearer...Thank you~

    Best Regards

    Minqiu

  • In reply to Minqiu Xie:

    Dear user:

    As long time not hear you, I assume you have solved the issue. I'll close this post.

    If not, just reply below. Thank you~

    Best Regards

    Minqiu

  • In reply to Minqiu Xie:

    Hi,

    Sorry for the late reply. A zener diode at the output of the converter parallel to the leds have solved the issue.

    Best Regards

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