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Switch between Constant Voltage (CV) and Constant Current (CC)

Posted by: phenpz on

Dear,

I would like to know if anyone knows how to make a source that has CV (constant voltage) with load from 0 to 5A for example, and by increasing this load, start to operate a CC (constant current), reducing the voltage and maintaining the 5A. PI have items for this?

Thank you

Comments

Submitted by PI-ODO on 02/27/2017

Dear Paulo,

 

What you describe is what is known as "CV/CC" operation, and indeed PI has multiple product families which support that profile, which is popular for battery charging.  The InnoSwitch, TopSwitch, TinySwitch, and LinkSwitch families are all possibilities, depending on your preferences.  For primary-side regulation, one can use LinkSwitch.  For secondary-side regulation, one can consider TopSwitch, TinySwitch, or InnoSwitch.  For <12W, TinySwitch is typically used; for >12W, TopSwitch.  InnoSwitch is also an option if one wishes to have secondary-side regulation without using an opto-isolator.

 

-PI-ODO

 

 

Submitted by phenpz on 03/01/2017

In reply to by PI-ODO

Dear PI-ODO,

Thanks for your answer :)

I had seen this CV / CC feature in PI Expert, but I did not understand how it works. How to control it? Which components are responsible for adjusting the current levels that I want the CV to operate, and the characteristic performance ramp.

Is there any document that explains?

For example follows a schematic generated by PI Expert with CV / CC, but that in the tests when reaching the 7A current, it cuts the output and does not reduce the voltage.

Thank you,

Attachment Size
PI Expert Online_sch.pdf 138.45 KB
Submitted by PI-ODO on 03/01/2017

Dear Paulo,

 

For a description of the expected CV/CC behavior, it is best to consult directly with the relevant datasheet.  For example, in the CC region, there may be an AR (auto-restart) threshold for some products that sets the voltage level where the output folds back to zero.

 

Other useful documents include our DER (reference design) reports.  For example, for TopSwitch, you can take a look at DER-580 at https://ac-dc.power.com/design-support/reference-designs/design-examples/der-580-118-w-high-line-input-non-pfc-cv-cc/.

 

You can see on p.35 the expected V/I profile:

 

-PI-ODO