TPS55010: Calculating maximum output level

Dan Andersen

Part Number: TPS55010

Is there a way to calculate the maximum level the output of the TPS55010 secondary could drift up to when unloaded and used in a standard flybuck configuration? My customer has an LDO follower and wants to make sure the input voltage range of the LDO is not exceeded when unloaded. I can share the exact schematic and coupled inductor spec.

Thanks,

Dan

over 7 years ago

0 Arief Hernadi over 7 years ago

TI__Mastermind 23845 points

Hi Dan,

Are you ok with adding a zener at the secondary of the flybuck as a crude OVP protection?

Thanks
-Arief

0 Dan Andersen over 7 years ago in reply to Arief Hernadi

TI__Genius 11450 points

They were hoping to avoid it - if they could figure out how high the output of the transformer could drift. Is there a way to calculate this easily or is general practice to simply clamp it?
Thanks,
Dan

0 Benjamin Lough over 7 years ago in reply to Dan Andersen

TI__Mastermind 26735 points

Hi Dan,

The secondary regulation is dependent on the leakage inductance, coupled inductor turns ratio and duty cycle with the worst case being when the primary output is fully loaded and the secondary output is unloaded. I am not aware of a reliable method for easily calculating the peak secondary voltage however.

Depending on how tight your regulation requirement is, you can clamp the secondary using a few different methods:
- Use a pre-load resistor
- Zener clamp as Arief suggested
- Soft Zener clamp (resistor in series with zener: www.ti.com/.../slyt392.pdf)

Hope this helps.

Best Regards,
Ben Lough

Power management

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TPS55010: Calculating maximum output level