TXB0104-Q1: TXB0104QPWRQ1 questions

Zhonghui Xu

Part Number: TXB0104-Q1
Other Parts Discussed in Thread: LSF0108-Q1, SN74AXC4T245-Q1, SN74AXC4T774-Q1, SN74AXC4T774, SN74AXC4T245

Hi team,

we are using your level shifter TXB0104QPWRQ1 for 1.8V to 3.3V convert, but we find the waveform have some problems.

1. when we using it for FM TDM signal(which is about 30MHz) level shifter, the 3.3V signal have two problems:

(1) the waveform level voltage cannot drop to zero, it even higher than 0.8V;

(2) it seems that the signal duty cycle is not the same as input, it much seems like exchanged with the input low level signal duty;

2. when we use it for the speaker TDM signal (which is about 12MHz), the signal is much better though it still cannnot drop to zero.

the following is out circuit

can you tell me the problem of it?

from your datasheet 1.8V to 3.3V level shifter should support 55Mbps. i want to know whether this 55Mbps means it can pass 55MHz signal or just the bandwith? should we change the level shifter to a higher part number such as LSF0108-Q1?

Thank you very much for your help.

Best regards,

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 316760 points

55 Mbps corresponds to 27.5 MHz.

An auto-bidirectional translator like the TXB (or TXS) cannot do buffering and has weak outputs. All your I²S signals are unidirectional, so you should use a direction-controlled translator like the SN74AXC4T774-Q1 or SN74AXC4T245-Q1. [edited]

0 guizhang chi over 3 years ago in reply to Clemens Ladisch

Prodigy 40 points

hi,Clemens Ladisch

thanks for your help. can we use bidirectional level shifter LSF0108-Q1 because we also have other application, we want to decrease the part category. and the SN74AXC4T774 or SN74AXC4T245 both are not automative part, we should use automative part.

0 Clemens Ladisch over 3 years ago in reply to guizhang chi

Guru 316760 points

The LSF works at these frequencies only with extremely strong pull-up resistors, which wastes lots of power, and requires the other devices to have high drive strength to avoid too-high low logic levels. You really should use the SN74AXC4T774-Q1 or SN74AXC4T245-Q1.

0 guizhang chi over 3 years ago in reply to Clemens Ladisch

Prodigy 40 points

hi,Clemens Ladisch

got it, thanks for your warmly help.

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TXB0104-Q1: TXB0104QPWRQ1 questions