[hpsdr] Demeter: Microcontroller regulated/controlled linear PSU

[Henry Vredegoor]

Hi Jeroen, All,

What about a microcontroller regulated/controlled low-voltage linear PSU?

If we are going to monitor/control the different voltages and currents with
ADC's and DAC's and have a microcontroller at hand anyway....

What does it do, how does it work?
A microprocessor senses the output of the regulating device by means of an
ADC (voltage and/or current) and adjusts the reference/input to the
regulating device by means of a DAC accordingly.

I've done some research on the web and this has been done before, look here:
http://www.linuxfocus.org/English/June2005/article379.shtml
and here:
http://www.emsp.tu-berlin.de/Members/Kusch/USBpower_report.pdf


This could also be a solution and a challenge to try and reduce the power
dissipation of a linear PSU.
There are known solutions which achieve this by maintaining a voltage of
abt. 1.0 Volts min. (to keep them saturated, regulating) to 2.0 Volts max.
(to limit dissipation) voltage difference across the series regulator power
device('s)).

Usually this is a sort of "raw power" pre-regulator; a full-on/full-off
switching power device which controls the average voltage input level to the
following series regulating power device.

I imagine a microcontroller equipped with some ADC's/DAC's is perfectly
suited for this task? 


Other possibilities/advantages (could all be done in software) might be:
- Temperature control/-compensation of the output voltage
- Soft-Power On/Off (switching on/off by logic levels)
- Soft-Start (Switch-on inrush current limiting in case of high power PSU) 
- Soft-Fuse (max. current limiting after initial inrush at switch on)
- Remote/Master/Slave On/Off/Standby
- Elaborate Power Good evaluation / -Indication 
- Standby (Low Power mode)


It would of course have to have some extra "real" hardware safety circuitry
to prevent disaster in case the microcontroller fails or the software
doesn't work correctly.

If this could be realized it would IMHO truly be a peer companion for a
HPSDR!
A true "HPSDHPSU" (High Performance Software Defined Hybrid Power Supply
Unit, ......... ;-)  )

I am aware of the fact that this is put very simply here.
But I think it can be done and could have some advantages worth
investigating.

Would like to hear opinions on this.

73's,

Henry.