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TL5001A: No PWM output and no sawtooth on RT pin

Prodigy 30 points

Replies: 7

Views: 179

Part Number: TL5001A

I am running a TL5001A on +5V VCC and do not see an output or a sawtooth waveform on the RT pin.  DTC is at 1.0 V, COMP is at 1.2 V, SCP and FB are grounded.  In an older design, I used the same configuration, but the VCC was +24 V.  Is the LVLO really 3. 0 V?

7 Replies

  • Hi Dan,

    Can you share me the schematic first? 

    Regards,
    Zack Liu
    Boost Converter Solution

  • In reply to Zack Liu:

    Hi Zack,

     

    Here is a snip of the area of the schematic with the TL5001A.  DCOM is the +5V return.  The lines going out from pin 6 go through resistors to open drain gates.  The voltage on pin 3 is 0.7 VDC.  Pin 1 is pulled up to +5V through an opto isolator diode in series with a 250 ohm resistor.

     

    Dan


  • In reply to Dan Geist:

    Sorry Dan. I don't understand the schematic that you show, what's the topology that you are using? Buck or Boost, I didn't see any MOSFET, inductor.

    Regards,
    Zack Liu
    Boost Converter Solution

  • In reply to Zack Liu:

    There is no MOSFET, no inductor.  The TL5001A just provides a PWM signal for another purpose.  The simple question is:  If I put 5V on the supply pin, provide signals in the range of operation for the comp and DTC pin and a 100k resistor on the RT pin, should I be able to see a sawtooth waveform on the RT pin?

    Dan

  • In reply to Dan Geist:

    Hi Dan,

    Once VCC voltage is higher than 3V, the sawtooth waveform should show up. Can you increase VCC higher to see when sawtooth will show up?

    Regards,
    Zack Liu
    Boost Converter Solution

  • In reply to Zack Liu:

    Hi Dan,

    Is there any difference if you increase VCC higher from 3V? Please check the IC is well soldered.

    Regards,
    Zack Liu
    Boost Converter Solution

  • In reply to Zack Liu:

    Hi Dan,

    I'll close this thread since haven't got any reply from you. You can post a new thread if you still have any questions.

    Regards,
    Zack Liu
    Boost Converter Solution

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