Hi void_error,
Please, dont make the mistake because Spice tels you its stable (power on, Power off and Load variation)
I did extensive testing on power supply's, and i can tell you, its is difficult to get it all wright.
Just test the real thing, you will be amazed how much Spice is lying to you.
Take a look @ this Dutch website (a lot of pictures!) how i measured the AC Ri. of a powersupply i'am designing.
http://www.circuitsonline.net/forum/view/110029/8/noise+amp+power+supply
Be aware that i use 2x 0,5M kabel to my Dummy Load, in the Dummy Load there is a 6,8uF capacitor (High Q)
This make's the ringing on the output of the power supply.
The better the power Supply the smaller the ringing
(its complicated, bandwith of the opamp, bandwith compound stage, ESR and L of the output capacitor, wiring etc.)
With de best compound output stage, and a fast opamp, there was only a view mV over and undershoot @ almost 10A change in load.
Thise is only possible with good wiring technics.
Keep up the good work!
Kind regarts,
Blackdog
One solution would be to use dual transistors, pretty hard to get compared to single ones but at least they'll be at almost exactly the same temperature. Not liking this. Another option might be to keep the transistors physically close which probably wouldn't be difficult with SOT-23 devices.
Either way I'm stuck here.
Hi void_error,
Please, dont make the mistake because Spice tels you its stable (power on, Power off and Load variation)
I did extensive testing on power supply's, and i can tell you, its is difficult to get it all wright.
Just test the real thing, you will be amazed how much Spice is lying to you.
Take a look @ this Dutch website (a lot of pictures!) how i measured the AC Ri. of a powersupply i'am designing.
http://www.circuitsonline.net/forum/view/110029/8/noise+amp+power+supply
Be aware that i use 2x 0,5M kabel to my Dummy Load, in the Dummy Load there is a 6,8uF capacitor (High Q)
This make's the ringing on the output of the power supply.
The better the power Supply the smaller the ringing
(its complicated, bandwith of the opamp, bandwith compound stage, ESR and L of the output capacitor, wiring etc.)
With de best compound output stage, and a fast opamp, there was only a view mV over and undershoot @ almost 10A change in load.
Thise is only possible with good wiring technics.
Keep up the good work!
Kind regarts,
Blackdog
Do you possibly have any related english text?
Here are the updated design goals:
Analog part
- Scalable for different output voltages/currents - up to 40V & 5A output using the same PCB
- Step-down switchmode pre-regulator which can go up to 100% duty cycle - for low output currents it will automatically be disabled to provide a cleaner output
- Not use highly specialized/hard-to-get parts
- Only one transformer winding fed into a bridge rectifier + filter caps or any fixed DC supply with the required voltage/current output used to power it
- Voltage/current can be set either using DACs or regular multi-turn pots
Digital part (optional, incomplete)
- MCU control
- Voltage/current and maybe other things displayed on an LCD
- USB interface
- Auxiliary 5V and/or 3.3V earth-referenced output to power logic circuitry (the USB connection to a PC will be mains earth referenced anyway)
As always suggestions are welcome.