UC1903: SENSE4 INVERT INPUT Unused Pin Termination

Kazuki Itoh

Part Number: UC1903
Other Parts Discussed in Thread: TPS37, TPS3704

Tool/software:

Hi team,

Regarding the UCC1903's 5th pin (SENSE4 INVERT INPUT), I have a question.
If this pin is not used, could you please instruct me on how to handle the terminal?
Looking at the internal block diagram, it appears that the pin is connected to the inverting input of the amplifier, and the non-inverting input is grounded.
Therefore, if the 5th pin is left open, I am concerned that external noise may cause malfunction.
To prevent this, I think it is necessary to fix the potential of the pin to an appropriate voltage (such as PU).
But in the other thread, it is recommended to leave it floating.

Best regards,

Kazuki Itoh

1 month ago

0 Henry Naguski 1 month ago

TI__Intellectual 1450 points

Hi Kazuki,

The other thread is correct, the sense 4 invert input pin can be left unconnected if it is not used.

May I ask if it is possible for you to use a newer device in your application? If the VDD max of 40V is required then perhaps a device such as TPS37 may be used instead. If a lower voltage is possible, we would recommend TPS3704.

-Henry

0 Kazuki Itoh 1 month ago in reply to Henry Naguski

TI__Genius 10770 points

Hi Henry,

I can suggest TPS37. But could you please comment on the noise vulnerability concern?

Why the sense 4 invert input can be left floating?

Best regards,

Kazuki Itoh

+1 Henry Naguski 1 month ago in reply to Kazuki Itoh

TI__Intellectual 1450 points

Kazuki,

We can only guarantee the performance listed in the datasheet and therefore cannot guarantee any noise vulnerability performance for this pin when it is left floating.

-Henry

0 Kazuki Itoh 1 month ago in reply to Henry Naguski

TI__Genius 10770 points

Hi Henry,

I received additional question from the customer.

Why does TI leave the pin floating while we cannot guarantee the noise vulnerability performance of the pin?

Does TI designed the device based on the assumption that the pin can be floating?

Best regards,

Kazuki Itoh

0 Henry Naguski 1 month ago in reply to Kazuki Itoh

TI__Intellectual 1450 points

Kazuki,

Unfortunately, we do not have any information about the design or specifications of this device beyond what is is the datasheet.

-Henry

Amplifiers

Amplifiers forum

UC1903: SENSE4 INVERT INPUT Unused Pin Termination