UCC20225: Supply high side

Max Av

Part Number: UCC20225
Other Parts Discussed in Thread: DRV8302

Hi,

I am using this IC to drive a bridge, it is necessary to be able to fill the PWM 100% using a bootstrap capacitor. How can I make an external charging pump circuit like in the DRV8302 chip?

over 4 years ago

0 Krystian Plaskota over 4 years ago

TI__Expert 4065 points

Hi Max,

Correct me if I misunderstand your question, but a bootstrap circuit on high side cannot support 100% duty cycle. I would recommend that you use isolated supplies for the high side. I am not aware of any external charge pump ICs to recommend.

Here are some reference designs we have using isolated supplies:

Regards,

Krystian

0 Max Av over 4 years ago in reply to Krystian Plaskota

Intellectual 470 points

Hi,

I thought so too, but the DRV8302 datasheet indicates support for 100% filling "Bootstrap Gate Driver With 100% Duty Cycle
Support". I would like to use a similar principle with a different driver.

0 Krystian Plaskota over 4 years ago in reply to Max Av

TI__Expert 4065 points

Hi,

We don't have a simple driver that has an internal charge pump that supports 100% duty cycle. Feel free to review the UCC5870, it has internal charge pump but the part might be excessive for your application.

Regards,

Krystian

0 Max Av over 4 years ago in reply to Krystian Plaskota

Intellectual 470 points

Hi,

Still, I don't understand.
For DRV8302, Texas Instruments claims 100% PWM support, isn't it?
I am interested in a similar scheme, only on external components.

0 Krystian Plaskota over 4 years ago in reply to Max Av

TI__Expert 4065 points

Hi,
I can check with the DRV team to see if they can assist. I don't know how the DRV8302's charge pump was designed so I can't offer advice to build an external one that is similar in principle.

Regards,

Krystian

0 Krystian Plaskota over 4 years ago in reply to Max Av

TI__Expert 4065 points

Hi,

Here is an app note that includes an external charge pump schematic. Please see figure 2 of this document and section 5, this should do what you want.

Regards,

Krystian

0 Max Av over 4 years ago in reply to Krystian Plaskota

Intellectual 470 points

Thanks!

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UCC20225: Supply high side