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Question on DCP021212D datasheet

Boxue Hu
Prodigy 70 points
Other Parts Discussed in Thread: DCP021212D

Hi.

I am using the isolated DC/DC converter DCP021212D.  And I am not clear about the parameters listed in the datasheet.

1) In section 5 of the datasheet, Device Comparison Table, the barrier capacitance is measured at Viso = 750 Vrms.  But according to the section 7.5 Electrical Characteristics, the chip can only sustain continuous 42.5 VAC or 60 VDC.  If the Viso is 750 Vrms, the chip can not survive. Does it mean the capacitance was measured within 1 seconds?

2) In the section 7.5. The difference between 1-second flash test voltage and continuous working AC voltage.  If I apply on the chip a continuous voltage, but it is several kHz square waveform, which parameter should I use?  

Thanks

Boxue

  • 0
    TI__Mastermind 38230 points

    Boxue:

    1. Paragraph 7.5 Every DCP02 including  DCP021212D  isolated  converter is required to pass the 1-second flash test 1kVrms confirming the minimum leakage across the isolation barrier.

     

             1a. Barrier capacitance Ciso 750V is based upon the 1kV 1 second  leakage test.

     

    1. In your application 1kHZ square wave continuous secondary operating voltage is limited to 42VAC and 60VDC

    2. See 8.1.3.1 Continuous working Voltage across he isolation barrier is limited to 42VAC  and 60VDC Peak,

    8.3.1.3 Continuous Voltage

    For a device that has no specific safety agency approvals (operational isolation), the continuous voltage that can be applied across the part in normal operation is less than 42.4 VRMS, or 60 VDC. Ensure that both input and output voltages maintain normal SELV limits. The isolation test voltage represents a measure of immunity to transient voltages.

    WARNING

    Do not use the device as an element of a safety isolation system when SELV is exceeded

    If the device is expected to function correctly with more than 42.4 VRMS or 60 VDC applied continuously across the isolation barrier, then the circuitry on both sides of the barrier must be regarded as operating at an unsafe voltage, and further isolation or insulation systems must form a barrier between these circuits and any user accessible circuitry according to safety standard requirements.

    8.3.1.4 Isolation Voltage

    Hipot test, flash-tested, withstand voltage, proof voltage, dielectric withstand voltage, and isolation test voltage are all terms that relate to the same thing: a test voltage applied for a specified time across a component designed to provide electrical isolation to verify the integrity of that isolation. TI’s DCP02 series of dc-dc converters are all 100% production tested at 1.0 kVAC for one second

     Tom

  • 0 in reply to Tom Guerin
    Prodigy 70 points
    Thank you for the reply.

    If I understand correctly, the 42.5 VAC or 60 VDC are for the operation personnel safety purposes. If the voltage applied across the insulation barrier is over 42.5 VAC or 60 VDC, the chip is still functioning, but no guarantee for personnel safety. Another insulation circuitry will be needed for the personnel safety.

    Is it correct?
  • 0 in reply to Boxue Hu
    TI__Mastermind 38230 points

    Boxue:

    The DCP02 is not designed  to have secondary voltages greater ≥42VAC or 6VDC.   The safety isolation barrier can be compromised if t\is voltage is exceeded. .

    Can you send me an e-mail with you contact information ?

    Tom

    tguerin@ti.com