TPS2660: TPS2660 Application issue

Sulyn ZHANG

Part Number: TPS2660

Hi Team,

My customer is using our TPS2660 in PLC AI module. Today they tested the plug in function, but they got strange waveform need your kindly support to explain, thanks!

As you can above waveform, the yellow one is the TPS2660's input waveform during plug in test, normally 24V bus voltage, but the pulse will up to about 50V and 50ms long duration. What may be the reason for this spike? Is these any problem? The green waveform is the output waveform of TPS2660.

Thanks a lot for your support!

Best regards,

Sulyn

over 7 years ago

0 Karikalan Selvaraj over 7 years ago

TI__Genius 16305 points

Hi Sulyn,

Can you please share the customer schematic to see what is at input of the PLC AI module apart from the TPS2660 that could cause the issue.
But from the waveform, TPS2660 is starting up after the voltage has reached near to 30V. Customer may have chosen OVP as 30V and that is why TPS2660 output is starting up after OVP.

Regards,
Kari.

0 Sulyn ZHANG over 7 years ago in reply to Karikalan Selvaraj

TI__Expert 8700 points

HI Kari,

Pls kindly find enclosed schematic, thanks! The OVP is set to 30V.

Best regards,

Sulyn

0 Sulyn ZHANG over 7 years ago in reply to Sulyn ZHANG

TI__Expert 8700 points

Hi Kari,

Can you help check this and give some feedback as customer plan to pp soon? They need to find the reason for this, thanks.

Best regards,

Sulyn

0 Sulyn ZHANG over 7 years ago in reply to Sulyn ZHANG

TI__Expert 8700 points

Hi Team,

This issue already pending for more than 2 days, Can anyone help on this urgent case? Thanks!

Best regards,

Sulyn

0 Karikalan Selvaraj over 7 years ago in reply to Sulyn ZHANG

TI__Genius 16305 points

Hi Sulyn,

Output ramp rate is programmed to 1.6ms and it is very fast for 100uF output capacitance. This would mean the inrush current could hit fast trip limit of 1.8A ( current limit is 1A). Due to this fast trip, input will see a inductive kick back and voltage at the input can jump higher and get clamped by 40V TVS.

Can you test with 0.01uF of dvdt cap (C315) and also capture input current waveform along with the input and output.

Regards,
Kari.

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TPS2660: TPS2660 Application issue