LM74800EVM-CD: Should I disconnect D1 from the EVM to observe over voltage clamp operation?

Yoshiki Ochi

Part Number: LM74800EVM-CD

Hi team,

Should I disconnect D1 from the EVM to observe over voltage clamp operation shown in "Figure 3-1. LM74800EVM-CD Schematic" in its user's guide?

I found that LM74800EVM-CD can observe over voltage clamping operation by connecting 1-2 on J6 shown in "2.3 Over Voltage Protection (J6)" in its user's guide.
However I also found that D1 or 33V TVS diode is connected to input side and OV clamp voltage looks 37.5V rising and 34.5V falling.

Regards,
Ochi

over 3 years ago

0 Praveen GD over 3 years ago

TI__Guru 57737 points

Hi Ochi,

In this case the OVP threshold (37.5 V) is set just above the minimum breakdown voltage of the input TVS (36.7V). To be on a safer side to avoid leakage in the TVS, you can remove the TVS or reduce the OVP threshold to a lower value, say 33V.

0 Yoshiki Ochi over 3 years ago in reply to Praveen GD

TI__Expert 7925 points

Hi Praveen,

Thank you so much. I understood we could remove TVS diode or modify dividing resistor network.

Regards,
Ochi

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LM74800EVM-CD: Should I disconnect D1 from the EVM to observe over voltage clamp operation?