LSF0204: Schematic review

Charles Jeon

Expert 2975 points

Part Number: LSF0204

Hi team

My customer want to review as the below.

Pull-up resistor will apply 1.5kohm.(R779, R780, R781, R782)

Check please.

Thank you.

over 5 years ago

0 Clemens Ladisch over 5 years ago

Guru 286060 points

Typically, I²C is so slow that you can get away with larger pull-up resistors; for 100 kHz, 4.7 kΩ should be fine.

The LSF0204 requires pull-up resistors on all I/Os. I am assuming that the SENSOR_xxx signals have pull-up resistors elsewhere. (And for 37 MHz, they must be quite small.)

0 ShreyasRao over 5 years ago in reply to Clemens Ladisch

TI__Guru 59120 points

yes, I dont see any pullup resistors on the A3/A4, B3/B4 ports.

The EN pin is referenced to the VrefA ( their vih and Vil levels). Would you be able to change that from VrefB unless really required? EN is overvoltage tolerant and can work by connecting it to VrefB as well.

0 Charles Jeon over 5 years ago in reply to ShreyasRao

Expert 2975 points

Hi Shreyas

SENSOR_RSTN and SENSOR_CLK are PUSH-PULL type.

So, I connected PULL-UP to A PORT (SENSOR SIDE) only.

SENSOR_CLK is 37.125MHz, 200ohm is connected to B port, 100ohm is connected to A port.

Please check, is there no problem with the switching speed?

0 Charles Jeon over 5 years ago in reply to ShreyasRao

Expert 2975 points

Hi Shreyas

SENSOR_RSTN and SENSOR_CLK are PUSH-PULL type.

So, I connected PULL-UP to A PORT (SENSOR SIDE) only.

SENSOR_CLK is 37.125MHz, 200ohm is connected to B port, 100ohm is connected to A port.

Please check, is there no problem with the switching speed?

0 ShreyasRao over 5 years ago in reply to Charles Jeon

TI__Guru 59120 points

Hi Charles,

If the sensor signals are push pull type, then the B port need no external pullup resistors, if going from B to A direction.

Logic

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LSF0204: Schematic review