Need more clarity on threshold voltage of UCC3915DP

Prakash SR

Hello,

We wanted more clarity on the voltage level of SHTDWN pin of UCC3915DP.

Datasheet mentions the Shutdown threshold as 1.1V to 1.9V, does it mean device will be in shutdown mode (Load turned off) when voltage on SHTDWN pin is with in 1.9V ?

When tested on two UCC3915DP IC's, load was turning ON when voltage on SHTDWN pin is 1.6V. So we wanted to know if the limits of 1.1V to 1.9V provided on the datasheet is for Turn ON or Turn OFF of load. Please refer attachment for schematic and waveforms.

Ti Support.docx

Thank you

over 7 years ago

0 Aleksandras_Kaknevicius over 7 years ago

TI__Genius 15710 points

Hi Prakash ,

This part falls under the Power Interface Forum. I will go ahead and move this post.

Thanks,

Alek Kaknevicius

Prakash

0 Eric Wright over 7 years ago in reply to Aleksandras_Kaknevicius

TI__Mastermind 42795 points

From the nature of the SHUTDOWN (with overbar) signal, the 1.5V typical threshold represents a falling signal applied to this pin. Once the signal falls below 1.5V, then the rising signal must go above 1.5V + 0.15V (hysteresis voltage) in order to turn back on.

The block diagram also seems to support this as the SHUTDOWN bar comparator has a 1.5V threshold reference voltage.

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Need more clarity on threshold voltage of UCC3915DP