My design for DC to DC converter using LM5175 is not working

KDN Nandu

Intellectual 750 points

Other Parts Discussed in Thread: LM5175

My design for DC to DC converter using LM5175 is not working, can anyone help me to know , what is problem?1.DSN.pdf

over 9 years ago

0 KDN Nandu over 9 years ago

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Is there any one, who can solve my problem

0 Vijay86929 over 9 years ago in reply to KDN Nandu

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Hi Nandu,

Can you describe in little more detail what specifically is not working? Waveforms for VIN, VOUT, SW1/2, Inductor currents etc will help as well.

0 KDN Nandu over 9 years ago in reply to Vijay86929

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Switcher is not working.

0 Philip McCorkle40 over 9 years ago in reply to KDN Nandu

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"Switcher is not working" is not a good explanation of the problem. Like Vijay said, can you give us some waveforms or any data at all?

0 KDN Nandu over 9 years ago in reply to Philip McCorkle40

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When I connect 12VDC I am getting output 12VDC and when I connect 24VDC then I am getting 24VDC output , same output as Input.

0 KDN Nandu over 9 years ago in reply to Philip McCorkle40

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Please find snap short of MOSFET Q15 and Q16, renaming two MOSFET at ground level.

operating frequency is 323KHz.

0 KDN Nandu over 9 years ago in reply to Philip McCorkle40

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New snap shot of Q5, Q6, Q15 and Q16.

Input voltage 13.71VDC ouput voltage 1.926VDC

0 KDN Nandu over 9 years ago in reply to Vijay86929

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How can I check if my IC is not dead.

0 Vijay86929 over 9 years ago in reply to KDN Nandu

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Hi,
There are a few ways to check it. For example, after ensuring that VIN does appear at the VIN pin of LM5175, please check the UVLO pin to ensure that UVLO is above the shutdown threshold.
Once these are satisfied, check VCC. It should be up and ~7.3V.
Checking gate drives also gives you some indication.Thanks and regards,Vijay

0 KDN Nandu over 9 years ago in reply to Vijay86929

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I checked voltage level is ok.

do I have to connect BIAS pin with external power supply.

0 Vijay86929 over 9 years ago in reply to KDN Nandu

TI__Genius 11490 points

Hi KDN,

The BIAS pin connection is optional. It provides an alternative BIAS input in case VIN pin is too low (to keep the part running) or too high (for lower loss).
Regards,

0 KDN Nandu over 9 years ago in reply to Vijay86929

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Thanks vijay for replay ,

I checked circuit , my feedback circuit is not proper, now i trying to correct if you get any other mistake, pls revert me.

0 Vijay86929 over 9 years ago in reply to KDN Nandu

TI__Genius 11490 points

The BIAS input is optional. It is needed only when VIN is not sufficient or to avoid excessive loss in the VIN to VCC regulator.

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My design for DC to DC converter using LM5175 is not working