This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

  • TI Thinks Resolved

ISO3082: 1st A&B output pulse after enable driver

Part Number: ISO3082

Hi,

In the test of ISO3082, we obverse both output A&B are driven to "low" at the 1st bit after enable driver. 

If the device work properly, when D = '0'

A='0', B='1'

But, from capture, when D = '0', after enable driver with D='1'

A='0', B='0' then turn to '1' after 0.8us. 

Is this the correct behavior for ISO3082?

Schematic: There is a modification on board R36 = R42 = 680 Ohm.

Waveform: CH1: RS485_TX(D); CH2: RS485-(B); CH3: RS485+(A); CH4: S485_EN(DE)

Thanks.

Zhou

  • Hi Zhou,

    Yes, this is expected. For ISO3082 the device would take typically 1.8us.
    Please refer to tpzh and tpzl parameters in section 6.11 of datasheet for additional details.

    Regards,
    Anand Reghunathan

  • In reply to Anand Reghunathan:

    HI Anand,

    tpzh and tpzl specified high impedance delay, but A&B are pulled low simultaneously.
    It is not the same thing specified in datasheet, right??

    Even though we remove R38, this waveform is still existing.

    Thanks.

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.