Post Go back to editing

Why does the switch circuit short-circuit when an IC chip is soldered on?

Category: Hardware
Product Number: ltc7151

The data manual of LTC7151 shows a typical application circuit as shown in the figure, which can achieve positive DC voltage input and negative DC voltage output.

So, I used it to draw a schematic diagram, as shown in the figure, to convert from 12V to -5.5V. After simulation, it was possible to achieve this, but there was a short circuit between -5.5V and GND in the resulting PCB board.

After investigation, it was not a problem with circuit board production or soldering. However, as soon as the chip is soldered, there will be a short circuit. Please help to see where the problem is with the circuit. Thank you tearfully.

Top Replies

  • FormerMember
    FormerMember
+1 verified

Hello,

This is expected to have a short at the start as there is no voltage at the negative terminal but should go away after probing for a few seconds.

Can you try a quick diode check if it shorts both…

  • FormerMember
    +1 FormerMember

Hello,

This is expected to have a short at the start as there is no voltage at the negative terminal but should go away after probing for a few seconds.

Can you try a quick diode check if it shorts both ways?

Regards,

Jhun

  • Hi Jhun,

    Thank you for your reply.

    What I want to express is that when the circuit is not powered on, there is already a short circuit between -5.5V and GND. After investigation, the short circuit occurred in LTC7151S. Remove LTC7151S and there will be no short circuit. At first, I thought it was a SMT issue, but after repatching, there was still a short circuit phenomenon. I don't understand what you're trying to convey. Where should I test?

    Regards,

    elevenboy