CV/CC settng & how it manifests in practice?

Posted by: natb1 on 06/16/2011

In PI Expert and using the CV/CC option I designed a 24VDC@2A supply using HX series controller.

I selected "1" for the CV/CC Threshold. Does this mean:

If output Voltage falls to <23VDC (Because of excessive load), the power supply will now act as a 2 Amp Current Source (max current limiting), allowing Vout to fall out of regulation (outer control loop). In this mode, the controller is operating in "current mode control" (inner loop) only? This is the behavior I want. I do not want "Hiccup Limiting / Reset".

Is this why PI recommends this selection for Battery Chargers?

Thank You

回應

It just signifies the voltage drop of the current sensing element on the output side.
You'll need 2 separate controllers one for CV region and one for CC region.

Thank You,

"2 separate controllers"?

You mean 2 TopSwitch ICs in the same Power Supply....or a 2nd feedback control circuit?

Do ALL Topswitch families enter a "shut down" mode when Vout falls below regulation?

Can I defeat this behavior such that TopSwitch continues providing maximum current?

Thanks

No. You need 2 error amplifiers. 1 for CV and 1 for CC region. There will still be one TOPSwitch on primary side.

Where is this load current sensing resistor & error amplifiers?
PI Expert designed no such thing in the schematic, even though I selected CV/CC option. It only designed a standard Voltage feedback via opto-isolator.
Do you have an application Note to implement this?

Thank You