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Tool/software:
Hi all,
I would like to use LSF0204DPWR in QSPI I/F line.
1. I want to use it in QSPI I/F(Bidirectional, no direction switching signal). Can I use it without any problem?
2. In case of QSPI, is pull-up resistor unnecessary in signal line?
If I want to add pulldown resistor, should I determine the constant referring to Table 10-3 in the datasheet?
Best Regard
Ryusuke
1. The LSF can work. It requires strong pull-up resistors to reach high speeds, so the devices must be able to sink that current.
2. Pull-up resistors must be used on the higher-voltage side, and should be used on the lower-voltage side.
3. Pull-down resistors must not be used.
Table 10-3 assumes that you already know what pull-up current you want. But that depends on the desired speed and the capacitance of the devices and the traces
You should use the TXB (without any pull-up/-down resistors), and you should not use long traces/cables.
Hi Clemens,
1) I understand that the LSF can drive QSPI, but it needs a pull-up resistor on the high voltage side.
What is the constant of strong pull-up resistor? Should I use the following diagram to determine the constant?
2) Do you recommend the TXB series?
Best Regards,
Ryusuke
1. The size of the pull-up resistor depends on the desired speed and the capacitance of the devices and the traces on your actual board.
2. Yes. Please note that the TXB also has restrictions; see my first answer.