RS232C / Internal pull up resistor

Sho Ogane

Other Parts Discussed in Thread: TRS232E, TRS202E, MAX3232E

Hi all.

I am looking RS232C device which has inernal pull up resistor at DIN1,DIN2 line like SP232E(EXAR) for my customer.
If you have such adevice, please tell me it.

I look forward to hearing your kind reply at your earliest convenience.

Best Regards,
Sho Ogane

over 9 years ago

0 Ron Michallick over 9 years ago

TI__Guru*** 145216 points

Sho,

TRS232E and TRS202E have pull up resistors.

The data sheet states this feature as Driver input current.

Edit: TRS202E does not have pull up resistors.

0 Sho Ogane over 9 years ago in reply to Ron Michallick

Genius 5575 points

Hi Ron san,

Thank you for quick reply.
I know that TRS232E and TRS202E have internal pull up resistors.
Which point can I know whether device has internal pull up resistors in the data sheet?

Sorry I have one more question.
Does MAX3232E have internal pull up resistor?

Best Regards,
Sho Ogane

0 Ron Michallick over 9 years ago in reply to Sho Ogane

TI__Guru*** 145216 points

Sho san,

TRS202E driver table. The IIH entry however doesn't make much sense

TRS232E driver table. Having a typical value would have been nice.

MAX3232E driver table. No pull up input resistor. The specification only allows for temperature induced junction leakages.

0 Sho Ogane over 9 years ago in reply to Ron Michallick

Genius 5575 points

Ron san

Thank you for your kind explanation.

I was able to understand the content very well.
I will check Low-level input current value for the future.

Best Regards,
Sho Ogane

0 Ron Michallick over 8 years ago in reply to Sho Ogane

TI__Guru*** 145216 points

Sho san,

I am sad to report that driver input current is not a reliable way to determine the presence of a internal pull up.
I confirmed that the 232 does have pull ups, however the 202 does not have pull ups on driver inputs.

0 Sho Ogane over 8 years ago in reply to Ron Michallick

Genius 5575 points

Ron san,

Thank you for your reply and confirming 232 and 202.

I understood that 232 has pull up and 202 doesn't have pull up,
I recommended 232 device for my customer, so I was relieved.

Thank you for the informing!
I am satisfied with your support.

We will contact you if there is question.

Best Regards,
Sho Ogane

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RS232C / Internal pull up resistor