Tool/software:
Hi,
Is it possible to bypass burst mode at low load on the UCC28951 ?
The ~10kHz vibrations are less desirable for my application than the losses during the initial battery charge times.
Thanks
Hello,
The low load bust mode is based on the minimum on time selected by Rtmin. When the voltage amplifier demands less than tmin the design will burst.
There is no way to disable this. However, you can set Rtmin to the lowest value of 10 k ohms which will give you a minimum on time of 50 ns roughly.
This will ensure the lowest duty cycle before entering burst mode.
Another thing you can do is add a little bit of pre-load to keep the design from bursting. This will just require adding a high impedance resistor to the output. I would only add what you need to keep the design from bursting.
Another thing that will help is making sure you have at least 200 mV of slope compensation. In this way when you have no load and very little current sense signal the slope compensation will act as a PWM ramp and allow you to control the duty cycle despite the lack of a current sense signal.
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Regards,