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CD4047B: CD4047 questions from customer

Sulyn ZHANG
Expert 8700 points
Part Number: CD4047B

Hi Team,

My customer is using our CD4047 and they have some questions here I want to search support from your side:

1. CD4047 working in unstable free running mode, pin 10 and pin 13 will output complementary pulse waveform, so how to define the dead time for this        complementary pulse waveform and can customer change this dead time?

2. When calculating the frequency, it is confusing to understand below transfer voltage, hope expert can help clarify on these:

3. Under free running mode and used as PWM waveform, do we have soft start function? If yes, how to realize the soft start function?

Appreciate for your support on these questions, this will be used in a new project, your support are appreciated!

Best regards,

Sulyn

  • 0
    TI__Guru* 96722 points
    Hi Sulyn,
    It sounds like the customer is trying to convert this device into an H-bridge controller for a motor or power supply. You won't be able to do that -- this is a very simple device and it's only intended to generate pulses. I would recommend looking into TI's wide assortment of controllers. It's very likely that we have a device that will support them more directly.
  • 0 in reply to Emrys Maier
    TI__Expert 8700 points
    Hi Maier,
    Thanks for your support. The application is small power Aux power, customer just want to use CD4047B to output complementary PWM signal. So would you pls help check above questions from customer, thanks a lot!

    Best regards,
    Sulyn
  • 0 in reply to Sulyn ZHANG
    TI__Guru* 96722 points
    1. There is no dead-time control for the CD4047B, it is a very simple oscillator, not a power controller.

    2. V_TR is used as a simplified means of describing the variation between units (process variation). The transfer voltages can be used with the equations given on the same page to determine the period of the waveform across all possible variations. It's much easier to just use the given min/typ/max equations given for TA:

    typ: T_A = 4.4*R*C
    min/max: T_A = 4.62*R*C

    3. No, soft start is a feature of power controllers, not for a simple oscillator like the CD4047B.