Use USB-C Port as Power Supply

CatSink is a free and low cost tool designed for use in the electronics laboratory or small projects that require a load supply of maximum 5 amps, this board works as a source of voltage and adjustable current.

CatSink has a USB-type C input designed to work with the Power Delivery (PD) protocol, this standard includes 4 different output profiles 5 V, 9 V, 15 V and 20 V and the amount of current is limited to power that the power supply can offer, at this time there are chargers of up to 100 Watts.

You can find its repository at https://github.com/ElectronicCats/Cat-Sink

This tool is designed so that it can be taken to any workplace together with a type-C PD charger or included in projects that need any of the output profiles mentioned above and keep it small.

Advantages of USB Power Delivery

• Increased power levels of existing USB standards up to 100W.
• The direction of energy is no longer fixed. This allows the powered product (peripheral) to provide the power.
• Optimize power management across multiple peripherals by allowing each device to draw only the power it needs and get more power when needed for a given application.
• Intelligent and flexible system-level power management through optional hub communication with PC.
• It allows low-power cases, like headphones, to negotiate only the power they need.

How to use a CatSink?

In the previous photo you can see two 4-position switch:

The first switch selects the amount of current to be provided (1 to 5 amps).

The second switch selects the amount of output voltage (5, 9, 12 and 20 volts).

These values ​​depend on the charger used when connecting to the USB port.

The following 2 examples show two types of chargers: one 30 Watt and one 100 Watt.

Example 1:

USB-C PD charger at 15 Watts 5v, 9v, 12v and 15v

If the charger in the previous image is used, the CatSink board will only be able to provide the following outputs:

Case 1:

The image above shows the selection from 5 volts to 3 amps.

As the PD charger provides up to 20 Watts, it can handle a voltage output of up to 3 amps without fault.

Case 2: Fault led ON

This happens when selecting some invalid profile for the loaded PD.

The charger cannot provide a 5 volt output at 5 amps.

This happens by the amount of current it can supply, which is limited by the power of the charger.

Power = Voltage x Current

When any of these inconsistencies are generated, the card goes into failure mode, turning on the indicator, indicating that the output voltage or current must change.

Example 2

USB-C charger DP 30 Watts (5v, 9v, 12v, 15v y 20v)

As shown in the table above with a 30 watt charger it is possible to use all CatSink profiles, providing a maximum of 5 amps of output for 5 volts.

Case 1:

The image above shows an output of 20 volts at 1 amp, the maximum output that the PD charger can provide.

Case 2:

The image above shows a voltage output of 15 volts, this profile does not exist directly in CatSink, however the PD charger does provide it. When selecting a voltage of 20 volts at 2 amps the charger cannot provide the necessary power and CatSink adjusts the output to 15 volts at 2 amps that the PD charger can provide.

Example: Catsink on load

The following image shows the power supply of 3 servomotors at 5 volts and consuming a total of 1.4 Amps, powered by a 30 watt PD charger using a CatSink card to regulate the power and a Bast Pro Mini M0 card to control the PWM signals.

Conclusion

When working with CatSink it is important to consider the power of the PD charger, if you are going to work with a high current it is necessary to check the temperature to avoid damaging CatSink although it works well at 5 amps in all its profiles.

It is an excellent laboratory or test tool where you do not have the option of carrying a voltage source with you.