TF360 Power Supply Discussion

[GadgetUK164]

Guess it depends on how many amps you need. There is a lot of intergrated chips but they tend to have poor internal MOSFETs for the switching. So once you get around the 1amp mark your mostly getting stuck with more complicated things.

I use a integrated chip for my PSUs. Probably the most efficient and runs the 5v rail, but needs a inductor and diode. The inductor is a issue as pissy small ones will get red hot so you don't end up better off.

I think the 060 needs around 7 amps on the 3.3v rail. So it will be tricky to get a small footprint with high power output. You could copy my 5v design and use a smaller inductor, which will run hotter. But the chip stays cool.

There may be better 3.3v solutions but the ones I went for were more adjustable then fixed voltages. Probably look at Texas intergrated chips and see what's there first. But you need the rdson like 20mR or lower else it will cook when pushing a few amps.

Its a bit of a minefield unfortunaly , and regulation is also a factor as I found, some chips really suck.

7 AMPS!!! Holy hell, that' can't be right? I would be amazed if it pulled more than an amp tbh. An entire Neo Geo MVS doesn't pull more than 1.3 amps, sure it's only running a 12Mhz 68000 but 7 amps?!?!?

[terriblefire]

Its a superscalar CPU so maybe... What does a pentium P60 draw?. it'll be similar numbers.

[techniplex]

I have used these Mini DC-DC Buck converters for other applications. Maybe they would work here. I have a few on hand if you wanted to give it a try.

1.Input Voltage:DC 4.5-24V
2.Output Voltage:integration adjustable and fixed output,back side can choose fixed output voltage
3.Adjustable Range:0.8-17V,fixed voltage (1.8V 2.5V 3.3V 5V 9V 12V)
4.Output Current:3A (max)
5.Transform Efficiency:97.5%(max) (6.5 to 5V 0.7A)
6.Switch Frequency:500KHz
7.Output Ripple Wave:20mV (12V to 5V 3A) 20m band width
8.Operating Voltage:-40 Celsius-85 Celsius
9.Output Overvoltage Protection:no
10.Static Current:0.85MA
11.Load Adjust Rate:±1%
12.Voltage Adjust Rate:±0.5%
13.Dynamic Response Speed:5% 200uS
14.Output Short Circuit Protection:yes
15.Input Transposition Protection:no
16.Enable Control:yes
17.Connecting Type:soldering
18.Input Way:soldering
19.Output Way:soldering/pin
20.Soldering Hole Space:2.54mm

https://www.aliexpress.com/item/Mini-DC ... 6a8d686c82

[Higgy]

On Chucky's Blizzard 1240 to 060 conversion page he fits a LT1085CM.

Looking at the datasheet it chucks out 3.3v @ 3A

https://www.analog.com/media/en/technic ... 8345fh.pdf

Am I rembering correct, as voltage goes down current goes up. So the voltage regulator should be happy if supplied with 5v @3A. I.e. a PSU rated with 4A on the 5v line.

[terriblefire]

On Chucky's Blizzard 1240 to 060 conversion page he fits a LT1085CM.

Looking at the datasheet it chucks out 3.3v @ 3A

https://www.analog.com/media/en/technic ... 8345fh.pdf

Am I rembering correct, as voltage goes down current goes up. So the voltage regulator should be happy if supplied with 5v @3A. I.e. a PSU rated with 4A on the 5v line.

Thats whats currently on the TF360.. its not up to the task.

[8 Bit Dreams]

John's board doesn't have RAM on it, that's big difference, cause it's also 3.3V

[exxos]

7 AMPS!!! Holy hell, that' can't be right? I would be amazed if it pulled more than an amp tbh. An entire Neo Geo MVS doesn't pull more than 1.3 amps, sure it's only running a 12Mhz 68000 but 7 amps?!?!?

Well , take it up with Czuba as its what he quoted for power requirements for the CT60. 8amps x 3.3v is still only 26watts.

EDIT: Also don't forget the 060 CPU's were (or can) be overclocked to around 100MHz, so need more juice for that as well.

ct60.jpg (56.28 KiB) Viewed 5898 times

[terriblefire]

John's board doesn't have RAM on it, that's big difference, cause it's also 3.3V

No the RAM is bugger all in the scheme of things. John's regulators are overheating above the normal operating temperature and I'm not comfortable releasing a design with them. I could not sleep at night knowing those were in the small space in a CD32s that someone might have left on.

We need a 4-6A SMPSU solution.

EDIT: Also don't forget the 060 CPU's were (or can) be overclocked to around 100MHz, so need more juice for that as well.

Indeed. Power squares with clock speed.

[terriblefire]

Am I rembering correct, as voltage goes down current goes up. So the voltage regulator should be happy if supplied with 5v @3A. I.e. a PSU rated with 4A on the 5v line.

No this isnt correct.

Power = Current x Voltage

Doing a simple ohms law substitution...

Power = Current^2 x Resistance (Current Squared x Resistance)

Hence the thermals go up on a curve the more power is required. And its the thermals that are the issue. At some temperature the regulator will go into thermal shutdown. So you can use a car battery or an arc welder to supply thing.... the problem is the same. That linear reg is not up to it if you want to go past 50Mhz with some RAM in a confined space.

[chucky]

Yeah I have been using the LT1085CM solution, as this is from "back then"

but. yeah it gets terrible hot, remember I am only selfthaught. I am quite poor in "analog" electronics etc. there must be a way better modern solution for this.

and in the CD32- yeah the heat cannot be good. especially when there is no real solution for active cooling.


(and for blizzard etc. well just using what phase5 used. the LT1085CM )

and for 100MHz. overvoltage to 3.5V is recomended.

I would say: look at the FPGA Arcade 060 DB and use that solution.