THVD1452: Pull up/down resistor

Takashi Yamaguchi

Part Number: THVD1452

Hi team,

My customer is considering to use the THVD1452. Could you please support the question below?

The Figure 38 in the d/s suggests to connect 10k pull up on R, and 10k pull down on DE. Don't need the 10k pull up on RE, and 10k pull down on D? If it doesn't need, could you tell me the reason?

Regards,

Yamaguchi

over 4 years ago

0 Clemens Ladisch over 4 years ago

Guru 319070 points

The R output has high impedance when the receiver is disabled. The pullup prevents the MCU's RxD pin from floating.

The DE pin already has a weak internal pulldown. The external pulldown is stronger to allow for larger noise currents (see point 6 in the layout guidelines).

0 Hao L over 4 years ago in reply to Clemens Ladisch

TI__Mastermind 25705 points

BTW, the REB and D pins have internal pull up. You could use external pull up for the reason Clemens mentioned.

Regards,

Hao

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THVD1452: Pull up/down resistor