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UCC2894: Practical Maximum Operating Temperature

Satyajeet Deshmukh
Prodigy 30 points
Part Number: UCC2894
Other Parts Discussed in Thread: UCC2891, UCC28C42-Q1, UCC28C52-Q1

Hello, I am trying to design an active clamp flyback with UCC2894D for an automotive application. The temperature requirement is 105 degC. According to the data given in the datasheet, the device supports this temperature although the TI website states the max operating temperature as 85 degC. I also checked the Failures in Time (FIT) rates data to be using 115 degC for testing.

Please let me know if I can safely use this device at 105 degC?

  • +1
    TI__Mastermind 23915 points

    Satyajeet,

    The max operating temperature for UCC2894 is -40°C<Tamb<+85°C. The max recommended junction temperature you see in the data sheet is -40°C<Tj<105°C and this is not the same as the -40°C<Tamb<+85°C you referenced. Operating the UCC2894 above +85C violates the data sheet and is not recommended. Also, UCC2891/2/3/4/7 family of active clamp PWM controllers are not available in -Q1 (not automotive qualified controllers).

    Thanks for connecting through E2E.

    Regards,

    Steve M

  • 0 in reply to Steven Mappus1
    Prodigy 30 points

    Thank you for your prompt response. Can you suggest a automotive qualified controller for controlling the active clamp flyback for continuous current mode?

  • 0 in reply to Steven Mappus1
    Prodigy 30 points

    Also I was referring to this when I mentioned the 125 in datasheet.

  • 0 in reply to Satyajeet Deshmukh
    TI__Mastermind 23915 points

    Satyajeet,

    I guess I would ask: why active clamp for automotive? Are you planning for power conversion from the low-voltage (LV) side or high-voltage (HV) side? If LV side, there is little benefit from active clamp ZVS. If HV side, the internal start-up can't be used and there are no p-channel MOSFETs rated for EV HV. For LV conversion, TI has UCC28C42-Q1 and for HV conversion we offer UCC28C52-Q1. Both are general purpose PWM controllers that do not include active clamp but are fully AEC-Q100 automotive qualified controllers well suited for CCM or DCM flyback and forward topologies.

    For whatever your input/output electrical requirements are, you might consider to download TI Power Stage Designer and you can compare the benefits between different topologies.

    Regards,

    Steve M