LM2587: Isolation between Input & Output voltage levels

vishnuvardhan reddy1

Part Number: LM2587
Other Parts Discussed in Thread: LM3478, UCC28711, LM1084

Hi,

I am trying to find a controller for flyback buck converter to convert 24VDC to 5VDC. I came across LM2587 on the way.

1. If we design using this controller and the transformer to convert from 24VDC to 5V DC,8A, do we get isolation between input side and the output side...?? please clarify.

2. Please suggest a controller for isolated DC-DC converter. Input voltage 24VDC & output voltage levels : 5V,8A; +15V,2.2A; -15V,1A requirement.

Thanks

Vishnu

over 5 years ago

0 Jasper Li over 5 years ago

TI__Mastermind 46905 points

Hi Vishnu,

I think output power is too high for this device. I would suggest use a boost controller for this application. I will find other expert to suggest a boost controller

0 Jasper Li over 5 years ago

TI__Mastermind 46905 points

Hi Vishnu

Please have a look at LM3478. this device is easy to used in flyback converter to generate isolate converter. by using flyback, we can use different winding to generate other output voltage.

0 vishnuvardhan reddy1 over 5 years ago in reply to Jasper Li

Prodigy 20 points

Hi Jasper Li,

Thanks for the suggestion.

I have used UCC28711 flyback design to output 24V DC. So, I will change the flyback transformer design to derive my 5V output. I think, the performance with UCC28711 (Primary Side Regulation DCM Operation) can be matched to LM3478/LM2587. If required, I will derive 6V output on the flyback secondary and then I use voltage regulator on the output side to get the regulated 5V output.

The high current requirement on 5V side is still a problem in above design. I could able to use LDO LM1084 at the output of the flyback transformer to get the regulated output 5V.

If check and comment.

Thanks.

Vishnu

0 Jasper Li over 5 years ago in reply to vishnuvardhan reddy1

TI__Mastermind 46905 points

Hi Vishnu

Considering the large output current, I think using a opto-coupler to regulate the 5V output voltage is higher efficiency solution and avoid using LDO.

The +-15V can be generated by additional winding, although the regulation accuracy will be not good as the 5V rail.

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LM2587: Isolation between Input & Output voltage levels