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About overcurrent of DAC8760

Gk 110
Expert 2440 points
Other Parts Discussed in Thread: DAC8760

Hello,

Our customer uses DAC8760.
When they use following conditions,it flowed overcurrent.

 - AVDD : 24V
 - They are referencing Figure88 of datasheet(Boost Mode Configration).
 - output current range : 0mA to 24mA

When they connected directly Ammeter without registor to IOUT pin,
the current increased to 100mA from 24mA.
Transistor was broken at the same time.

When the current increased,that is occured nothing in Status Registor.
And it wasn't output of the signal from ALARM pin.

They connected thermal PAD to GND plane.
Could you please tell me the cause of the over-current?
If you want to confirm detail,I have a circuit diagram of a customer.
So I can send at E-mail.

Best regards,

Manabu Ito

  • 0
    TI__Genius 10615 points

    Hello Ito-san,

    I have a few questions to help me debug this issue.

    MANABU ITO said:
    When they connected directly Ammeter without registor to IOUT pin,
    the current increased to 100mA from 24mA.
    Transistor was broken at the same time.

    What was the state of the DAC at this time? Was it powered on?

    Was the output enabled?

    Did it have another load attached?

    Did the device break or only the external transistor?

    More description of the conditions when this occurred will help replicate this test in my lab.

    MANABU ITO said:

    They connected thermal PAD to GND plane.

    What is AVSS connected to?

    MANABU ITO said:
    If you want to confirm detail,I have a circuit diagram of a customer.

    Thank you for the offer. This would be very helpful, but first i need to make sure that it is okay to contact you to your registered E2E email.

  • 0 in reply to Eugenio Mejia
    Expert 2440 points

    Hello Mejia-san

    Thanks for your quick reply.

    I answer your question.


    What was the state of the DAC at this time? Was it powered on?
    -> Yes,it was.

    Was the output enabled?
    -> Yes, it was.

    Did it have another load attached?
    -> NO,it didn't.

    Did the device break or only the external transistor?
    -> They connected external transistor.
        P/N is  CPH6223-TL-E of ONsemi.

    What is AVSS connected to?
    -> AVSS connected to GND.

    Our customer are very troubled.
    Could you please elucidate the cause?

    Best regards,

    Manabu Ito

  • 0 in reply to Gk 110
    Expert 2440 points

    Hi Mejia-san

    I do the information updates.
    Our customers did verification of variety.

    They are referencing Figure88 of datasheet(Boost Mode Configration).
    They changed to 100Ω from 20Ω.
    This points to the R2.

    Phenomenon of the overcurrent by this measure was improved.
    Is it correct treatment?

    If it is correct actions that they adjust the value of R2, please tell me the appropriate value of R2.

    They use following conditions.

      - AVDD : 24V
      - They are referencing Figure88 of datasheet(Boost Mode Configration).
      - output current range : 0mA to 24mA
      - They use transistor of ONsemi(CPH6223-TL-E)

    Best regards,

    Manabu Ito

  • 0 in reply to Gk 110
    TI__Genius 10615 points
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