LSF0102: LSF0102 Uart Reading error

Marcelo Diniz

Part Number: LSF0102

Tool/software:

Hello

How to use LSF0102 for UART.
I can't get correct readings with it, using TXB0104 works fine, but I need to use LSF0102 in this project.
I'm not using pullup resistors on LSF0102.

1 month ago

0 Jack Guan 1 month ago

TI__Mastermind 42236 points

Hi Marcelo,

Is there a reason why the pullups cannot be used with the LSF0102? The device has open drain outputs, and would need external pullups to achieve the logic high state especially on the higher voltage side (B1/B2).

Regards,

Jack

0 Marcelo Diniz 1 month ago in reply to Jack Guan

Prodigy 10 points

Hi Jack,

Can you tell me the values of the pullup resistors?
I will use for UART and not I2C

0 Clemens Ladisch 1 month ago in reply to Marcelo Diniz

Guru 317870 points

This depends on the maximum signal frequency and the capacitance of these traces on your board. 4.7 kΩ should be OK.

0 Marcelo Diniz 1 month ago in reply to Clemens Ladisch

Prodigy 10 points

The frequency is 115200 it seems that I have an impedance problem at input A1 and B1

0 Jack Guan 1 month ago in reply to Marcelo Diniz

TI__Mastermind 42236 points

Hi Marcelo,

115KHz is supported by the LSF0102 as the frequency is achieved via the external pullups selected.

Can you please help clarify with continuity checks/ ABA swap to see if potential soldering issue? Otherwise please provide waveforms of signaling of A1/B1 for further debugging.

Regards,

Jack

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LSF0102: LSF0102 Uart Reading error