IRS2113 SD pin noise sensitivity

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User16464
Level 1
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Just a note for other users, I recently changed from using an IRS2110 (lower floating voltage version) and encountered a persistent fault in an H-bridge
where it looked like high side UVLO (the high side just stopped working) even though the low side continued working. I spent ages scoping the high side
and changing components in the boost circuit to no avail. Eventually in desperation I grounded the previously floating Sd pin and the fault went away!
I should emphasize this was a swap from an IRS2110 to an IRS2113 in the same pcb in a previously working circuit. Both date codes concerned 713P
so it seems maybe I was lucky before or the 2113 is more sensitive, in either case I would never rely on the internal pulldowns again.

Has this site never heard of an editor that wraps!
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Hi,

Even though data sheet says grounding is unnecessary but in your case, due to near by signals it would be catching some noise .So, I request you to make it solid ground and test once more.

BR,

AZIZ HASSAN

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Srivatsa
Moderator
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First comment on blog 10 sign-ins First like received
What is the VDD and VCC voltage in your design?

The Sd pin has a weak pull down internally. It is recommended to ground the pin if unused.
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User16464
Level 1
Level 1
Hello, my VCC is 12V & VDD is 3V3.

Unfortunately the data sheet implies grounding is unnecessary and I think I left it floating for future use however on closer inspection of the data sheet it seems the pulldown resistance is undefined! At best there is a TYPICAL value for input leakage but no minimum.....
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Hi,

Even though data sheet says grounding is unnecessary but in your case, due to near by signals it would be catching some noise .So, I request you to make it solid ground and test once more.

BR,

AZIZ HASSAN

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