TAM - Aux PSU for Expansion Card(s) in Development . . .

. . . hopefully!

Start of this project was info about the anemic TAM PSU issue from many sources, here, MLA, WWW and ThinkClassic back in that day.
Was working on putting together a better Initial Post, but what the heck . . . just chuck it out to the pack of wolves!

First notion was a PicoPSU inside years ago, but recently been thinkin' about USB-C.




Looks to me like only 12V & -12V would be handled nicely? Those are for disk drives, no? What else?

Whatcha' think? Is is even possible to take the pressure off the TAM's pathetic 5V and 3.3V rails with an AuxPSU Hack on a new riser design?
Next evolution of the project will be TwinSlot/TAM in the upper right corner. 6360 version PCBs are in, look good and on the way to me for function testing . . . very soon now!


edit: typo in files, the 6" Pigtail is USB-3 running in Mac supported USB-1 role.

luRaichu said:

USB PD 3.1 supports up to 240W, should be plenty for a TAM.
It can only output one voltage at a time, you would need a power supply that converts its 20-48 VDC into your +5V, +12V, -12V rails.

Click to expand...

So USB-C is the rough equivalent of a Switching Power Supply? Might a couple of BIG MOHONKING CAPACITORS even out those switching effects?

luRaichu said:

And it would have to work with the soft-power switch...

Click to expand...

The power from USB-C AuxPSU to the cards would be continuous and unrelated to soft-power silliness in the rest of the TAM. It won't be replacing the TAM's PSU, just feeding the Riser's power line cutouts.

As in the IP: is 12V and -12V even used by PCI Cards in the TAM? Should be able to leave those voltages to the anemic TAM PSU's rails to feed those voltages to the TwinSlot/TAM Riser, I'd think?

My thinking on trying this madness IRL would be a jumper cutout on every power line of the TwinSlot/TAM riser:
- fit headers on all lines for baseline testing of the TAM Riser.
- match sockets on the AuxPSU protoboard to the risers power cuttouts.
- AuxPSU experimental circuits could be done via Wire Wrap to the TAM Riser, perf board works fine for such things.

Could experiment with powered and unpowered riser that way. However TAM's pathetic PSU reportedly can't handle a single PCI Card, CSII Card and G3/L2 Accelerator all at the same time.

TwinSlot/TAM riser would be useful for getting around a Single PCI Card power dilemma for the TAM.

Pulled post from Parallel MLA thread:
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Did a more refined diagram in AI8:



In parallel TD thread, It came up that USB-C can only output one voltage at a time. But the little Power Converter/Power Supply is the only powered device and only pulling one voltage from USB-C, so it should be continuous?

Pathetic TAM PSU is on its own in supplying 12V and -12V to the Logic Board Riser Connector, hence to cards on riser. Target Cards for TwinSlot/TAM would be Video Card in the standard (Single Slot FatBack Riser) location with the USB/FW Card moved up and set back into the loft where the NIC would be in standard FatBack configuration. I'll post pics of the TAM test setup I did in my 6360.

Soft power came up as well, so first reaction was to heck with Soft Power, the Riser/Cards would be receiving power continuously no matter what the silly machine thought was going on. Today I did a re-think and realized that it'll likely be easy enough to to a circuit on the Riser to detect 12V on its lines at startup and then begin feeding 5V/3.3V to the card stack. When Riser detects power cutoff on 12V lines on TAM shutdown, it cuts off 5V/3.3V supply, so card stack is only receiving power while the TAM is running. The little Artekit PSU will be powered up and on standby, but not the cards. Still no Soft Power tomfoolery involved!
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From the Artekit info page linked below:



The AK-USBSUPPLY-C board takes power from an external power supply through an USB type C cable and delivers 3.3V and 5V through two dedicated pins. You can use this board to supply 5V and 3.3V to other peripherals and boards by using a standard wall charger, USB hub or a PC USB port.

The CC1 and CC2 pins of the USB type C connectors are connected to ground through two 5.1K Ohm resistors. This means that when the AK-USBSUPPLY-C board is used with the right power supply and cable (wall charger or hub with USB-C standard, for example) it can deliver up to 3A on the 5V rail and 800mA on the 3.3V rail (the board mounts an STMicroelectronics LD1117 low-dropout regulator for generating 3.3V, with a maximum output current of 800mA). When used with a USB 2.0 host or power supply, the board can deliver maximum 500mA on both the 3.3V and 5V rails.

There is also an on-board green LED connected to VBUS that signals when the board is receiving 5V from the external power supply.

We also ship this a power supply from USB with a mini conector: the AK-USBSUPPLY board.

Features and Characteristics​

• Maximum output current:
  • 5V pin: up to 3A (USB-C standard)
  • 3.3V pin: up to 800mA.

DigiKey Product Page
Artekit Guides - Listed as Datasheet on DigiKey

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