LM27213: Bidirection DC DC converter question.

John Griffith

Mastermind 22052 points

Part Number: LM27213
Other Parts Discussed in Thread: LM5170

Hello,

I have a customer that is looking to design a bi-directional DCDC converter and is interested in the hysteretic current control of the LM27213 device. They have two questions:

When a new lower voltage command is sent to the chip, is the inductor current allowed to reverse and pull current out of the output cap and send it to the input cap (turning it into a boost converter) or does the output just sag with the output load until it reaches the new commanded voltage?
They would like to override the VID inputs to the DAC. Can I set the output voltage by tying the STP_CPU# pin low and applying a voltage to the VSTP pin?

Thanks,

John

over 8 years ago

0 Brani Dubocanin over 8 years ago

TI__Expert 4100 points

Hi john,

I will forward your question to an expert for this device.

Regards

Brani

0 Mathew Jacob1 over 8 years ago

TI__Expert 5910 points

John,

I don't think this would work in the way you are planning to use as a bi-directional converter. Check out LM5170 that is designed for this application.

Regards,

Mathew

0 John Griffith over 7 years ago in reply to Mathew Jacob1

TI__Mastermind 22052 points

Hi Mathew,

Sorry for the delay in following up and thank you for the response. The customer stated that they didn't like that the direction pin would have to be externally controlled and that the controller was not able to switch between sourcing and sinking current depending on what the output voltage was. They are concerned that this will then require software to be developed which is a long process for medical applications.

Can you think of any devices that would be able to handle this automatically? My other thought was possibly using a comparator or a supervisor to control the direction pin "in analog"?

Thanks again,

John

0 Mathew Jacob1 over 7 years ago in reply to John Griffith

TI__Expert 5910 points

John,

I cannot think of a part that supports this. Yes the analog method would work.

Regards,
Mathew

0 John Griffith over 7 years ago in reply to Mathew Jacob1

TI__Mastermind 22052 points

Thanks for the help, I will close this out and follow up with the customer.

John

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LM27213: Bidirection DC DC converter question.