ADM3252E output issue!

Dear friends,

Recnetly, We have a cusotmer found ADM3252E will output 0x 00 or 0x FF when the system power on, in order to confirm if the CPU or ADM3252E output the error data, we have broken the connection between CPU and ADM3252E, but the issue is still exit, could you give some comments about the issue, many thanks!

  • 0
    •  Analog Employees 
    on Aug 25, 2015 3:03 PM over 5 years ago

    Hi Eason,

    Is the customer seeing an issue with the Receiver output pin, or the Transmitter (Driver) output?

    Can you please supply a schematic for the customer setup?

    Are there Pull-Up or Pull-Down resistors located on the Transmitter or Receiver pins?

    Are the decoupling capacitors the same as those shown on Figure 16 of the data sheet?

    Best Regards,

    Richard

  • Hi Richard,

    Many thanks for your reply, for your comments, kindly please find the following description:

    1) Is the customer seeing an issue with the Receiver output pin, or the Transmitter (Driver) output?

        The issue was only found in the transmitter output pin.

    2) The following is the customer schematic

    3) Are there Pull-Up or Pull-Down resistors located on the Transmitter or Receiver pins?

        We have tried to add the Pulll-Up resistor for the transmitter pin, but the issue is still exit;

    4) Are the decoupling capacitors the same as those shown on Figure 16 of the data sheet?

        The decoupling capacitors were the same as the datasheet Figure 16;

  • 0
    •  Analog Employees 
    on Aug 26, 2015 7:46 AM over 5 years ago

    Hi Eason,

    Thanks for the feedback.

    I just have a few more questions to help me to better understand the customer's application.

    Is the customer seeing this issue during power supply ramp up?

    How long does the power supply take to ramp up? (do you have an oscilloscope plot?)

    Is the Vcc operating voltage 3.3V or 5V ?

    What is connected to the Tout pins? Are you seeing issues with Tout1 or Tout2 or both?

    Best Regards,

    Richard

  • Hi Richard,

    Sorry for the delaied reply, kindly please find the following reply for you questions about ADM3253E:

    1) Is the customer seeing this issue during power supply ramp up?

    Reply: The customer has found the issue during power supply ramp up and ramp down;

    2) How long does the power supply take to ramp up? (do you have an oscilloscope plot?)

    Reply: The following is the sequence diagram ramp up and ramp down:

    Power supply ramp up:

    Power supply ramp down:

    3) Is the Vcc operating voltage 3.3V or 5V ?

    Reply: The Vcc operating voltage is 3.3V;

    4) What is connected to the Tout pins? Are you seeing issues with Tout1 or Tout2 or both?

    Reply: The Tout pins is the RS-232 connector and connect with the RS-232 jack of  PC. The issues are exist both on Tout1 and Tout2.

  • 0
    •  Analog Employees 
    on Sep 7, 2015 9:33 AM over 5 years ago

    Hi Eason,

    Please see the ADM3252E data sheet.

    For the Power-Up transient:

    Figure 13. Typical Output Voltage Start-Up Transient, VCC = 3.3 V.

    We can see that the start-up transient is load dependent.

    This corresponds to the first image that you have provided.

    For the Power-Down transient :

    Can you please ask the customer to repeat the measurements with a slower Vcc ramp up/ramp down.

    I would like to see if the part is powered-down at a slower rate do we still see this behavior.

    Best Regards,

    Richard