TXB0304: CLK signal fail

Tommy Tzeng

Part Number: TXB0304

Hi Team,

may we know as below issue?

1.Can TXBN0304RSVR be used for SPI signal?

2.there is have level shift TXBN0304, the measures SPI_CS0_18, SPI_CLK_18 signal is abnormal, remove the IC and then measure SPI_CS0_18, SPI_CLK_18 signal is normal, as shown below

what could be the reason?

over 4 years ago

0 Clemens Ladisch over 4 years ago

Guru 316690 points

I'd guess the load is too high; see sections 8.3.1 and 8.4.2 of the datasheet. What have you connected to the I/Os?

0 Tommy Tzeng over 4 years ago in reply to Clemens Ladisch

Genius 5760 points

Hi Sir,

customer have pull hight resistor on SPI_MISO_18(4.7Kohm), and what can be improved?

TMP current load is very small, as shown in figure below TMP spec.

and what other possible reasons make the SPI clock signal abnormal?

0 Clemens Ladisch over 4 years ago in reply to Tommy Tzeng

Guru 316690 points

That pull-up resistor is too strong for the TXB.

But the CLK problems look like ringing. I'd guess the capacitance is too high; how long are the traces? Are there connectors or cables?

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TXB0304: CLK signal fail