UCC2808A-1: UCC2808A Wide Input Range

Hirotsugu Kobayashi

Part Number: UCC2808A-1

Is it possible to achieve a circuit of Fig.2 of ucc2808 data seat?
The input voltage area which is 72V from 36V by Push - Pull system, can it correspond?

over 7 years ago

0 John Stevens over 7 years ago

TI__Expert 7395 points

Kobayashi-San,
Thank you for your interest here. Please excuse the delays until January 3rd as it is US holiday now.
Figure 2 if the data sheet seems to be a curve for Idd vs. Osc frequency. What circuit figure are you referring to? Your design needs input voltage range from 36-72v , is that correct? What is your output voltage and current?
Regards
John

0 Hirotsugu Kobayashi over 7 years ago in reply to John Stevens

Mastermind 8895 points

John-san

I'm seeing rebesion SLUS456D of a dataseat.

The circuit which is being asked is attached.

Best Regards,

0 John Griffin1 over 7 years ago in reply to Hirotsugu Kobayashi

TI__Mastermind 34465 points

Hi Kobayashi-san,
The data sheet for this part has recently been revised. The latest revision is now SLUS456E.
The application section is now shown in Fig. 11.
The input voltage varies from 36V to 72V and has a nominal value of 48V.
The output is 5V at 50W max.
This application is detailed as a design example and is not available as a reference design.

Regards,
John Griffin

0 Hirotsugu Kobayashi over 7 years ago in reply to John Griffin1

Mastermind 8895 points

Hi John
It's mentioned that the input voltage range is from 36V to 72V by a design parameter of Table.2 of a data seat.
But our costomer think it's difficult to correspond to a wide input voltage range with Push-pull topology.

Can UCC2808A correspond to a double input voltage range?

Best Regards,
Kobayashi

0 John Griffin1 over 7 years ago in reply to Hirotsugu Kobayashi

TI__Mastermind 34465 points

Hi Kobayashi-san,

The push pull can be designed for this wide voltage range.

For example if the output duty cycle is 90% at 36V (corresponding to 45% duty cycle on each gate drive) then the required output duty cycle will be 45% at 72V
(corresponding to 22.5% duty cycle on each gate drive)
Does that make sense? Of course it is always difficult to design a power supply with a wide input range but it is possible to do so with the right care and attention to details

Regards,

John

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UCC2808A-1: UCC2808A Wide Input Range