MAX232 Overheat

Hello.
I have some problems with the MAX232.

In some cases, when I pluga and turn on the system (with contains the max232), the IC will be inoperated and overheat too much.
In other cases, the RX will work OK, but TX not work.

I don't know wich's the cause of my troubles...

I hope help me.

Best Regards
fede

  • In reply to Ives de Oliveira:

    I too can confirm even with the cap connected to Vcc, I experience overheating.

    That said, I have also managed to combat the problem by fitting a 20R resistor in series with the power feed. The resistor was initially intended to limit the current draw if the intermittent fault manifested itself but testing after installing has show the fault to disappear completely. Even when I induce the fault by momentarily shorting the capacitor, I observe no latchup.

    Please let me know if this works for you.

     

    Regards

    Dave

    G4UFS

     

  • In reply to David Pearson:

    I have the same problem with MAX202. It occurs randomly when power is applied to the circuit. Connecting the other end of the capacitor on pin 2 to VCC or GND does not make any difference.

  • In reply to Kmz Tan:

    Will anybody from TI suggest a real solution? I have many boards with this problem and the MAX202 part is exactly the same as the circuit in the datasheet.

  • In reply to Kmz Tan:

    Kmz Tan,

    I have tried multiple times to create this effect in the lab unsuccessfully. Would you be willing to send in a couple units that are prone to overheating?

    Regards,
    Ron Michallick

     

     

    Regards,
    Ronald Michallick
    Linear Applications

    TI assumes no liability for applications assistance or customer product design. Customer is fully responsible for all design decisions and engineering with regard to its products, including decisions relating to application of TI products. By providing technical information, TI does not intend to offer or provide engineering services or advice concerning Customer's design. If Customer desires engineering services, the Customer should rely on its retained employees and consultants and/or procure engineering services from a licensed professional engineer (LPE).

     

  • In reply to Ron Michallick:

    Hi Ron,

    Unfortunately, I cannot send any of these units since they are all on the boards assembled. We used 1 uF capacitors with MAX202 based on the statement "The MAX202 requires 0.1 uF capacitors, although capacitors up to 10 uF can be used without harm." on page 7 of the datasheet. When we replaced the capacitors (all of them) except the power supply decoupling one with 100 nF in a few boards, we observed that the problem does not occur. I think the problem occurs because the charge-pump circuit sometimes does not start with 1 uF capacitors.

    Regards,

    Kmz

  • In reply to Kmz Tan:

    Kmz,

    Thanks for the information. What type of 1uF capacitors were used, tantalum, ceramic, or other?

    Regards,
    Ron Michallick

    Regards,
    Ronald Michallick
    Linear Applications

    TI assumes no liability for applications assistance or customer product design. Customer is fully responsible for all design decisions and engineering with regard to its products, including decisions relating to application of TI products. By providing technical information, TI does not intend to offer or provide engineering services or advice concerning Customer's design. If Customer desires engineering services, the Customer should rely on its retained employees and consultants and/or procure engineering services from a licensed professional engineer (LPE).

     

  • In reply to Ron Michallick:

    Ron,

    They are ceramic capacitors.

    Regards,

    Kmz

     

  • In reply to Kmz Tan:

    was the problem solved? I have the same problem. I have MAX232ID and all capacitors installed as described in datasheet. But sometimes (not very often) MAX232 overheats a lot!!! Power cycle usually helps.

    It happens when RS232 side is disconnected, but TTL part is connected to MCU.

    What can be the cause of the problem?

  • In reply to Vladimir A:

    I've three Maxim MAX232CPE IC having symptoms as described by you in this thread, mainly gets hot on power-up.

    I've prototype circuit conforming to reference schematics, but TTL ports connected to uC.

    The circuit operates correctly when Ti MAX232, or ST 232BN  IC is used instead.

  • In reply to Pawel Janicki:

    Hello,

    I have exactly the same overheating problem and I explained the problem in detail at the below link.

    http://e2e.ti.com/support/interface/etc_interface/f/392/t/233847.aspx

    David suggests connect a 20 ohm resistor to VCC and I applied this. I'm not sure but this solution seems solved the overheating problem.