LSF0102-Q1: large pull up resistor

Lee, Sam

Part Number: LSF0102-Q1
Other Parts Discussed in Thread: TXB0104-Q1, TXU0304-Q1, TXU0104-Q1

Hello team,

LSF0102-Q1 is level shifting 1.8V to3.3V for UART in a platform. BW, unless there is an issue on UART receiver(57600bps) although TR is slow, is it okay to use 47kohm as the pull up resistors of 3.3V side?

FYI. This is because TXB0104-Q1 in a debugging board will be connected to the UART nodes (3.3V side) of LSF0102-Q1 with disabling LSF0102-Q1.

Thanks,

Sam Lee

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 316690 points

The TXB might not work with 47 kΩ pull-ups (see section 8.3.5 of the datasheet).

I would recommend to replace both translators with TXU0104-Q1, TXU0204-Q3, or TXU0304-Q1.

0 Lee, Sam over 3 years ago in reply to Clemens Ladisch

TI__Expert 6025 points

Hi Clemens,

Yes, I understand your point for TXB.

However, can you confirm that the 47kohm for LSF0102-Q1 is okay?

Thanks,

Sam Lee

+1 Clemens Ladisch over 3 years ago in reply to Lee, Sam

Guru 316690 points

Yes, the LSF will work with 47 kΩ at the low-voltage side.

Logic

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LSF0102-Q1: large pull up resistor