MAX3223: Transmitter section failure of MAX3223IPW

Anurag Bajpai

Part Number: MAX3223

Hi in one application for MAX3223IPW , the force on is connected with invalid bar pin with zero ohm resistor. By mistake the force on is also connected with ground using zero ohm resistor. Initially the ic was working fine, now the tranmit section on RS 232 is sending garbage while the recive section of rs232 of ic is working fine. Can you tell due the invalid bar pin is connected to ground has done the damage to the IC?

Thank you.

4 months ago

0 Clemens Ladisch 4 months ago

Guru 327600 points

/INVALID is a push/pull output; shorting it to the wrong voltage indeed might damage the device. But it's possible that that wrong connection simply pulls V_CC down, and that removing that connection will fix it.

0 Ethan Sempsrott 3 months ago

TI__Mastermind 29862 points

Hi Anurag,

Thanks for reaching out on E2E.

I agree with Clemens' statement above since INVALID is an output. I would recommend removing the zero Ohm resistor that connects the INVALID pin to the Forceon pin going forward (so INVALID isn't permanently shorted to GND). Forceon can stay shorted to GND.

Best,

Ethan

0 Anurag Bajpai 3 months ago in reply to Ethan Sempsrott

Prodigy 10 points

Hi Ethan,

Thank you for your reply. This is used for communication with MK70 NXP controller and outside world. This IC worked around 6 months in same configuration for multiple power cycle operation. Now it is showing garbage. The query is how it worked for this much time.

0 Anurag Bajpai 3 months ago in reply to Clemens Ladisch

Prodigy 10 points

Hi Clemens,

0 Ethan Sempsrott 3 months ago in reply to Anurag Bajpai

TI__Mastermind 29862 points

Hi Anurag,

It is possible that the transceiver was slowly damaged over time. I would measure the exact Forceon and Forceoff voltages during operation, and I would try disconnecting the Invalid pin to see if the failing device works.

Best,

Ethan

0 Anurag Bajpai 3 months ago in reply to Ethan Sempsrott

Prodigy 10 points

Hi Ethan,

Thank you for your reply. Now i changed the IC with new one and using configuration where /INVALID is connected to forceon but there no resistor between forceon and ground so /INVALID is not connected to ground now. Hope this configuration will work.

Regards

Anurag Bajpai

0 Ethan Sempsrott 3 months ago in reply to Anurag Bajpai

TI__Mastermind 29862 points

Hi Anurag,

Either way, that is the proper setup for this device. If you run into more issues, just reach out again.

Best,

Ethan

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MAX3223: Transmitter section failure of MAX3223IPW