One Four All – Low-Noise Audio PSU
- 5V input via USB-C or wires:
- At least 2A USB supply recommended, heavy loading requires 3A.
- Use USB power bank for fully isolated power.
- 5V input is boosted and filtered before regulated for output.
- Generates the following supplies from a single 5V input:
- VD – 5V digital, up to 400mA.
- VA – 6V analog reference supply, up to 150mA.
- VP/VN (+/-13.3V analog amplifier/opamp supply), up to 250mA per supply.
- Molex Micro-Fit power output connectors to power multiple Kaamos boards (subject to current limits) with simple connections:
- 2-pin Molex for digital-only boards.
- 6-pin Molex for mixed-signal boards.
- All output connectors are in parallel so total current per supply must be within the limits.
- Extensive protection features for increased reliability and robustness:
- Power-up sequencing to decrease inrush current.
- Input reverse polarity protection.
- Input over-voltage protection and under-voltage shutdown.
- Current limit and under-voltage shutdown on each output channel; if one shuts down, all shut down.
- Soft-start and soft-stop to toggle the PSU between standby and active states.
- Mute output to quickly mute DACs in case of output failure.
One Four All powering DAR 18 and W-DAC XLR.
Power switch
One Four All (OFA) has a soft-start and soft-stop switches that toggle between standby and active states. However, we strongly recommend turning the PSU completely off when not in use – a solid advice for all electronics. To do this, you can unplug the USB-supply or turn off the supplying power bank; however, we also provide a placeholder for a hard power switch. The placeholder header is in series with the power input and shorted by default so that the board is ready to use; however, we do recommend wiring a switch here if the input power supply is not easily unplugged.
VIN pad above is in parallel with the USB power – do not use both simultaneously. PWR SW is a placeholder for the power switch and is shorted with a wire by default.
As with input wiring, the wiring for the power switch and the switch itself should have low resistance to minimise voltage drop between the supply and the board. See the board guide for more information.
User instructions
Upon power-up, the PSU turns on automatically. All output channels are turned on in a sequence to minimise start-up current spike. Successful ON-state is signalled by the ON-LED. If soft-stop is engaged, the PSU goes to standby state and the OFF-LED is lit. Soft-start turns the outputs on again.
Should the OFF-LED light after a power-up, please see startup troubleshooting in the OFA Guide.
Active-high (around 5V) mute output can be used to signal standby-state to external circuits.
Important information on order
- All required SMD components are soldered down and the board is fully tested.
- USB-connector, one 6-pin Molex output, one 2-pin Molex output, and SMD-pinheaders are soldered down. The rest of the connectors are provided unsoldered (unless solder down option is selected); this allows you to solder wires to the power outputs. Power switch connection is shorted so the board is ready to use.
- Please ensure you have the skills to solder the remaining components and wires to connect the board in your system – and most of all understand what you are doing.
- If you need help prior to purchase, please contact us.
Order contents
The board is delivered with following parts included:
- Fully tested board with all SMD components populated.
- 3pcs 6-pin Molex power connector (1 soldered down).
- 3pcs 2-pin Molex power connector (1 soldered down).
- 3pcs 1×2 male SMD-pinheader (soldered down).
- PCB panel mount kit for USB-end:
- 2pcs small L-brackets.
- 4pcs 4-40 1/4″ bolts.
- PCB bottom mount kit:
- 2pcs 6mm standoff.
- 2pcs M3 bolt with 2.5mm hex end.
- 2pcs M3 nut.
- 2pcs M3 flat washer.
- 2pcs M3 teeth washer.
More information
See the One Four All Guide for more information on the following topics:
- Input voltage range and impact of wiring resistance.
- Number of boards OFA can supply.
- Soft-start and soft-stop.
- OFA startup problems.
Files
- Schematics may be released later on
- Component placement and board dimensions
