am26c31cn damage problem

Federico Maidana

Other Parts Discussed in Thread: AM26C31, AM26LV31E, AM26C32Hello I have a product in which am26c31cn and am26c32cn are used. The connection between them is as follows: Pins Y and Z of 26c31 connects pins A and B of 26c32 respectively, with resistances of 100ohm between lines Y and Z (or A and B). The four pair of connections in the IC are used. The problem is that occasionaly am26c31cn reaches very high temperatures that damage the device. The power supply is correct, there are no overvoltages, no short circuits. I would like to know if there is some external component I should use or something I am doing wrong. Thanks

over 14 years ago

0 Ron Michallick over 14 years ago

TI__Guru**** 165176 points

Hello Federico,

I suspect that the initial device damage occurs just before the device will overheat. Most often damage to the driver will cause excessive current flow and this will increase the temperature and cause more damage.

The 100 ohm resistor should be on the AB pins but not the YZ pins. The purpose of the resistor is to prevent reflections back down the cable.

The AM26C31 does not have a strong resistance to ESD and EOS. If 3.3V is availble in your system I susgest using the AM26LV31E instead.
It has much better ESD and EOS protection and uses less power.

If staying with the AM26C31, adding protection diodes from Y and Z to GND and VCC and a small series resistance (10 ohms) to the Y&Z outputs will make a more robust system.

Regards,
Ron Michallick

0 Federico Maidana over 14 years ago in reply to Ron Michallick

Prodigy 30 points

Thanks for the reply.

I will consider the protection diodes and small resistances because it's not posible to use 3.3V version.

I missed an important detail. In my circuit, I'm using am26c31 and am26c32 to establish a communication beetwen two separated boards that don't share the same Ground.

Is it critical for am26c31 and am26c32 to have the same Ground?