MAX3232 in parallel

Joaquin Gonzalez

Other Parts Discussed in Thread: MAX3232, TRS3232

Hi to everybody,

Is there any problem if I connect a MAX3232 output to two Max3232 inputs, so I can sen the same data to two receivers at the same time.

Thanks in advance.

Nuba

over 12 years ago

0 Ron Michallick over 12 years ago

TI__Guru**** 165666 points

Nuba,

The only concern it that each RIN input a has a 5k ohm internal load resistor. Therefore the RIN load will be typically 2.5k ohms which will lower the RIN voltage.

0 Joaquin Gonzalez over 12 years ago in reply to Ron Michallick

Expert 1200 points

Hi Ron,

Thanks for your answer. I would say that the voltage would remain the same (since the resistor is in parallel configuration) but this configuration will increase the current that the driver has to deliver (now it is feeding two receivers). Since the current would be under 35mA, I supose there won't be any problem.

Have anybody try this before?

Thanks in advance for the help.

Nuba

0 Ron Michallick over 12 years ago in reply to Joaquin Gonzalez

TI__Guru**** 165666 points

Nuba,

You are correct the current will nearly double. There are differences in driver performance based on the RS232 driver used. All drivers can tolerate 3k which is the minimum specification in the MAX3232 data sheet. The expected range for RIN on MAX3232 is 5k +/-20%. So the load potentially could be as low as 2k with two receivers. This is why I said the voltage may be lower.

Connecting the two receivers will work except for cases with highest speed, longest cables, and noisiest environments.

Here are two driver output curves.

0 Joaquin Gonzalez over 12 years ago in reply to Ron Michallick

Expert 1200 points

Thanks Ron

0 Joaquin Gonzalez over 12 years ago in reply to Ron Michallick

Expert 1200 points

Hi again Ron,

Do you have similar curves like the one you posted befor but for driver MAX3232?

Thanks

0 Ron Michallick over 12 years ago in reply to Joaquin Gonzalez

TI__Guru**** 165666 points

Nuba,

MAX3232 is same as TRS3232 in every way except for first three letters in device name.
Therefore the TRS3232 curves apply to MAX3232.

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MAX3232 in parallel