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PWM Controller with different dead times

Valentin Zeller
Prodigy 20 points
Other Parts Discussed in Thread: LM5105, LM5036, UCC28250

Hi guys,

I'm looking for a PWM controller (or a different solution) for a half bridge in a switched mode power supply (~500 kHz) which can provide a different dead time between the transistion Low -> High  and High->Low.
All controllers or drivers I found yet just provide the same deadtime for the two transistions.

As an alternative I'm thinking to work with delay elements.

 

Thanks for your help!

Valentin

  • 0
    TI__Mastermind 31580 points

    Hi Valentin,

    The LM5105, www.ti.com/.../samplebuy bridge&tisearch=Search-EN-Everything, is a half bridge driver with programmable dead-time but they are symmetrical.

    Our latest half bridge controller is the LM5036 again I don't think it has the different dead time between the transistion Low -> High  and High->Low, .

    The UCC28250/1 is another recent half bridge controller,

    For the asymmetrical deadtime you may have to go down the route of implementing discrete delays.

    Regards

    Peter

  • 0 in reply to Peter Meaney
    Prodigy 20 points

    Hi Peter!

    Thanks for you answer!

    I will try to realize it with delays. Any suggestions for adjustable delay components?

    Valentin

  • 0 in reply to Valentin Zeller
    TI__Mastermind 31580 points

    Hi Valentin

    I have used simple asymmetrical delay networks to slow turn-on and for faster to off.

    Turn on is through an RC circuit, the C is maybe some 10's of pF or cap across the gate soucre of the mosfet and turn-off is through a diode with maybe a series resistor which are in parallel with the R in the RC circuit.

    I hope this helps.

    Regards

    Peter