Boost controller with Adjustable Vout

Phil Salisbury

Other Parts Discussed in Thread: PMP20212, PMP30722, POWERSTAGE-DESIGNER

Hello,

I am looking for a non-isolated boost controller to boost +24V +/- 5% up to a variable Vout of +26.5 to +32.5V with Iout of 8A at +32.5V. I need to drive the adjustment from a voltage ouput DAC.

The LM5123 with TRK pin looks promising but a short list of IC's to consider would be very helpful.

Thanks

Phil

over 3 years ago

0 Richard Fu22 over 3 years ago

TI__Mastermind 31015 points

Hi Phil,

Currently, the most suitable IC that can suit your application is the LM5123. However, you can use other boost controllers, such as the LM515x controller family. You can follow the adjustment voltage scheme shown in PMP20212: https://www.ti.com/tool/PMP20212 or PMP30722: www.ti.com/.../PMP30722

If you would like to calculate the value, I would suggest using the powerstage-designer calculation tool: https://www.ti.com/tool/POWERSTAGE-DESIGNER#tech-docs. There is a feature that allows for dynamic analog output voltage scaling.

Thanks,

Richard

0 Phil Salisbury over 3 years ago in reply to Richard Fu22

Prodigy 240 points

After a little more research I found slvaej4.pdf which discusses designing adjustable boost mode switchers. With this and your suggestion I think I have what I need.

Thanks

Phil

0 Phil Salisbury over 3 years ago in reply to Phil Salisbury

Prodigy 240 points

Power Stage Designer is very helpful--thanks.

I have a few more questions:

In today's supply-chain environment I find most TI parts are unavailable including all LM51xx. LM3478MA seems to be available. Do you think is an adequate choice?

I have OrCAD & PSPICE and I downloaded the TI LM3478MA model so I am doing simulations to understand operation at 26V-32V. I have yet to find a balance but still working it.

Which conduction mode is best (CCM or DCM) for variable output design? I would trade efficiency to minimize voltage dips due to load transients.

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Boost controller with Adjustable Vout