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TL594 High frequency operation

tateo yamashiro
Guru 10890 points
Other Parts Discussed in Thread: TL594

Hi,

My customer has question about TL594.
Could you tell me about questoin?

[Question]
- My customer considers to use TL594 for high frequency boost convertor, such as higher than 120kHz.
  Because they want to use small inductor.
  They consider to set push-pull mode and C1 and C2 connect to gate of MOSFET.
  And C1 and C2 are alternately turned on and off.
  Please see figure below.


  If oscillator is set 60kHz, they are thinking that switching frequency can be 120kHz.
  Can the device use this usage?

Best Regards,
tateo

  • 0
    TI__Expert 3200 points
    Tateo,

    When I look at the datasheet I do not see a reason this connection would not work at as an effective 120 kHz switching frequency however, you need to pull-up the C1 and C2 outputs to VCC or something that Q1 can tolerate. Note that this is a common-emitter configuration so I assume a P-channel MOSFET is being used.

    I will forward this question to the Team within TI that owns this PN to add additional comments.
  • 0 in reply to Brian Johnson96
    TI__Mastermind 24885 points
    Hello Tateo-san,

    Yes, as Brian mentioned you can use it this way, but you will need a pullup on the gate of your FET assuming you are using a PFET.

    You could also just set the device to single ended mode, with the OUTPUT CTRL pin pulled to ground and set the switching frequency to 120kHz. This device can manage a switching frequency up to 300kHz. You set the frequency as shown in Section 9.3.2 Oscillator.

    Best,
    Michael