UCC28C42 non isolated design

PAN-M

Other Parts Discussed in Thread: PMP10833, PMP10834

Dear all.

Our customer' request is BUCK converter, they don't want to use a transformer.
For example, can we correspond to this request in PMP10833?
When regarding the maximum of the AC input max. is 265V, output of 5V is 1.3% pluse width.
Can this be controlled by UCC28C42D?

If you have any design sample, please teach me.

Regards,
PAN-M

over 9 years ago

0 Peter Meaney over 9 years ago

TI__Mastermind 31580 points

Hi Pan,

I have contacted the design engineer who worked on the PMP10833, he is the best person to answer your question on this application.

Regards

Peter

0 PAN-M over 9 years ago in reply to Peter Meaney

Mastermind 8375 points

Peter
Thnk you for support.
If you need any business information, please send me e-mail directry. (see my profile)
Regards,
PAN-M

0 Sheng-yang Yu1 over 9 years ago in reply to PAN-M

TI__Expert 4750 points

Hi Pan,

Yes, you can use UCC28C42D for a HV buck. Another example is PMP10834:
www.ti.com/.../pmp10834.
Also, to reduce switching losses, we generally design the converter to be operated at DCM. Therefore, the duty cycle at maximum input will be less than 1.3%.

Regards,
Sheng-Yang Yu

0 PAN-M over 9 years ago in reply to Sheng-yang Yu1

Mastermind 8375 points

PMP10834 uses a transformer and photo-coupler.
Can you change these circuit?
Regards,
PAN-M

0 Sheng-yang Yu1 over 9 years ago in reply to PAN-M

TI__Expert 4750 points

Hi Pan-M,

PMP10834 uses a standard coupled-inductor to provide high enough VCC voltage for the controller and high voltage MOSFET. It 's also possible to power the controller directly from the rectified input. That way, you could replace the coupled-inductor by inductor. Using photo-coupler in PMP10834 is for higher output voltage regulation accuracy need. A high side Buck like PMP10833 usually sense the output voltage only when the freewheeling diode is conducting. An RC filter is generally used to hold the sensed output voltage signal. This type of feedback sensing generally give you worse output voltage regulation. That is why I use photo-coupler for PMP10834 since it is for 5V output.

Regards,

Sheng-Yang Yu

0 PAN-M over 9 years ago in reply to Sheng-yang Yu1

Mastermind 8375 points

Pls. teach to me little more.

Is over current 3A? (0.33 ohm)
Do you have efficiency data at 1.5A?

Regards,
PAN-M

0 Sheng-yang Yu1 over 9 years ago in reply to PAN-M

TI__Expert 4750 points

Yes, over current is at 3A.

I don't have efficiency data at 1.5A. However, I expect the efficiency at 1.5A will be around 68% at 120VAC and 63% at 230VAC.

Regards,

Sheng-Yang Yu

0 mechaniK over 8 years ago in reply to Sheng-yang Yu1

Prodigy 180 points

What is the switching frequency of the converter in PMP10833 ?

0 Sheng-yang Yu1 over 8 years ago in reply to mechaniK

TI__Expert 4750 points

The switching frequency is set to be 45kHz. The oscillator equation of UCC2813 can also be used here: Fsw = 1.5/(RT x CT).

Reagrds,

Sheng-Yang Yu

0 mechaniK over 8 years ago in reply to Sheng-yang Yu1

Prodigy 180 points

The inductor value in reference design is I think 100uH or 330uH.

If I want to convert the operation from DCM to pure CCM, would it be possible to do it by using a large value inductance say 1mH [with saturation current rating in excess of 2A] and a SIC freewheeling diode to increase efficiency? [Cost no bar]

My output voltage requirement is 60V 1A non Isolated.

0 Sheng-yang Yu1 over 8 years ago in reply to mechaniK

TI__Expert 4750 points

Sorry for my late response. Yes you can have your converter operates at CCM mode with larger inductance. As you said, you will need to use SiC diode to reduce the switching losses. An example is attached.

Regards,

Sheng-Yang YuPMP10783RevA_sch_.pdf

Power management

Power management forum

UCC28C42 non isolated design