THVD1550: DE / RE pin 2 MΩ internal pull-down / UP question

AJ Cheng

Genius 3615 points

Part Number: THVD1550
Other Parts Discussed in Thread: THVD1505

Hello.

I saw THVD1550 SPEC description "2 MΩ internal pull-down / UP" on DE and RE pin. Is it new function of THVD1550 ?

May I know why such a design increase. Thanks~

over 7 years ago

0 Hao L over 7 years ago

TI__Mastermind 25705 points

AJ,

The pull down and pull up circuitry were there in some other RS485 transceivers, like HVD78, HVD82. The value is specified in THVD1505 to help some customer to design their digital interface. Please let me know if you have other questions.

Regards,

0 AJ Cheng over 7 years ago in reply to Hao L

Genius 3615 points

Dear Hao.
Thank you for your reply. May I know what kind of design need to pay attention to such a specification. Thanks~

0 Hao L over 7 years ago in reply to AJ Cheng

TI__Mastermind 25705 points

AJ,

For example, if you want to change default state by adding external pull up or pull down resistors at the pin, you would know how much resistance you need to override the internal one. Some customers asked such information before. Please let me know if you have more questions.

Regards,

Hao

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THVD1550: DE / RE pin 2 MΩ internal pull-down / UP question