UCC27714: Output signal not following input signal

Umesh D

Part Number: UCC27714

Tool/software:

Hello team,

I am using UCC27714 for half bridge LLC converters switching. while testing bootstrap circuit I am getting HO as continuous high and LO as 0.

My input signal is having sufficient dead time. EN pin pulled to high with 200k resistor and HS, HO, HB pins are giving continuous high (18V) as Vdd voltage.

Please help me with this as we are running out of time.

Thanks & regards,

Umesh D,

Medha servo drives.

6 months ago

0 Vincent Liew 6 months ago

TI__Intellectual 830 points

Hi Umesh,

Thank you for the question. Would you be able to share the schematic? Also just to clarify, are HO and HB showing 18V with respect to GND or with respect to HS?

Best regards,

Vincent Liew

0 Umesh D 6 months ago in reply to Vincent Liew

Prodigy 20 points

Hi Vincent,

HB, HO and HS are giving 18V with respect to with respect to GND (VSS/COM).

Mean time I'll share the schematic.

Best regards,

Umesh

0 Vincent Liew 6 months ago in reply to Umesh D

TI__Intellectual 830 points

Hi Umesh,

Thank you for the clarification. I will be waiting for the schematic.

Best regards,

Vincent

0 Umesh D 5 months ago in reply to Vincent Liew

Prodigy 20 points

Hi Vincet,

I am using the SCT3040KR, a 4-pin SiC MOSFET with a separate Kelvin source connection. Are there any specific PCB layout considerations required due to the separation of the Kelvin source and the power source terminals?

Best regards,

Umesh.

0 Hiroki Honda 5 months ago in reply to Umesh D

TI__Genius 9186 points

Hi Umesh,

Responses will be delayed due to US holiday.

Our dedicated expert will get back to you shortly.

Regards,

Hiroki

0 Vincent Liew 5 months ago in reply to Hiroki Honda

TI__Intellectual 830 points

Hi Umesh,

Since the MOSFET has separate driver and power grounds, please have the driver ground of the FET connected to the UCC27714. This is to keep the high current through the FET separate from the gate drive loop. This may not be necessary if you are using a sufficient ground plane.

Since HO-HS and HB-HS are 0V, the problem may be with the bootstrap circuit. Would you be able to share the schematic?

Thank you,

Vincent

0 William Moore 4 months ago in reply to Vincent Liew

TI__Genius 14145 points

Hey Umesh,

I am closing this thread at this point due to no further questions.

If you have any questions regarding this topic you can reply and reopen the thread.

Thank you,

William Moore

Power management

Power management forum

UCC27714: Output signal not following input signal