Depending upon their capability, USB-C PD adapters and chargers can source a variety of different voltages and currents. This is typically 5V, 9V, 12V, 15V and 20V up to 100W (for PD version 3.0).
The adapter will initially provide either 5V (to support legacy protocols) or no voltage at all (if USB-C PD only). To obtain 5V or a higher voltage, the sink device needs to request this.
For USB Power Delivery, the mechanism is that the source (adapter) will advertise its capabilities through a series of PDO or power delivery objects and the sink will request the desired voltage and current creating a power contract. This communication occurs via the communication channel lines CC1 and CC2 found on USB Type-C connectors at 300kbaud using Biphase Mark Coding (BMC).
A ‘trigger’ board, like the one pictured below, can be used to request the desired power contract from the source device (normally a power adapter or power bank). These boards can normally be found very cheap at the normal electronic sources such as Aliexpress, Amazon, Banggood and ebay. Search for terms such as USB type C ‘trigger’ or ‘decoy’. The board below was sourced from the Tenstar Robot Aliexpress Store.
The board provides provision to solder a screw terminal block (not included) on the output. This can then be connected to the device requiring power. This could be integrated into your own electronics, or connected to a DC power cable with an appropriate connector on the end (i.e DC 2.1 or 2.5mm socket) to plug into a device – camera, router etc.
Schematic
The board pictured above is based on a CH224 from Chinese Semiconductor manufacturer Nanjing Qinheng Microelectronics Co., Ltd under the WinChipHead (WCH) brand.
The CH224 is a series of “USB-PD and Other Fast Charging Protocol Sink Controller” integrated circuits designed to operate as a sink controller for a variety of charging standards including USB-C PD, Qualcomm Quick Charge and Samsung Adaptive Fast Charging. Some variants of the chip incorporate a high voltage regulator or internal pull-up resistors on the CFG pins, while others support I2C allowing an external MCU to request different voltage and current profiles.
The CH224 family appears to be stocked by LCSC Electronics.
The board above incorporates the common CH224K variant (LCSC Part # C970725). This device doesn’t have the high voltage regulator.
According to the english datasheet (version 1F), the CH224K has a typical VDD voltage of 3.3V and a maximum of 3.6V. It appears with the inclusion of a series current limiting resistor and probably with the help of the internal ESD diodes or perhaps a zener, the device can operate on higher voltages as per WCH’s reference schematic below.
It is therefore curious why this board has increased the BOM count by using a LM78L05 – 5 volt linear regulator. This may be to prevent overstress at higher voltages – i.e. 20V.
It appears CFG1, CFG2 and CFG3 has been reordered to help optimise the PCB layout and as such S1, S2 and S3 do not directly correspond with the datasheet. The table on the rear of the device has been changed to reflect the PCB change.
S1 and S2 (CFG2 & CFG3 respectively) have 1k pull up resistors, while CFG1 has 10k. According to the datasheet CFG2 & CFG3 do not have internal pull-up resistors and are 5V tolerant.
The LED appears to be powered directly from the regulator (and VBUS). The device has a power good pin – it would have been good to see the LED attached to this pin instead.
USB-C power delivery is negotiated on the Configuration Channel (CC) pins. The USB data positive (DP) and negative (DN) pins are not required for USB power delivery, but allows the controller to fall back to other fast charging protocols (AFC: Samsung Adaptive Fast Charging, and QC2.0/QC3.0: Qualcomm Quick Charge Version 2 or 3).
Testing
Testing with a variety of chargers (USB-PD and legacy) at no load was successful over the range of voltages.
However, load testing at 20V quickly killed the device when the DC load was switched off – possibly due to an inductive spike through the USB cable.
A quick meter test with 5V applied via the USB-C socket showed the LM78L05 regulator was working, but there was no voltage on the CH224K’s VDD pin. This was shorted to ground (approx 3.3 ohms) and was current limited via the 510 ohm series resistor.
Removing the 510 ohm series resistor and powering VDD via a 3.3V bench power supply showed it was drawing about 260mA. In this state, some of the device was still functional. It could negotiate power using the Quick Charge V2 protocol, but not USB PD suggesting the DP and DM pins were unscathed, but the CC1 & 2 pins were also damaged.
It appears an electrical over-stress condition most likely killed the device. It is not clear if this occurred via the VDD pin, or the USB-PD configuration channels – CC1 or CC2. The datasheet suggests the absolute maximum voltage for on the CC pins for a CH221K variant is 8V, and is increased to 32V for the CH224Q/A variants. But, at the same time the absolute maximum voltage for the VDD pin goes from 5.8V on the CH221K variant to 32V on the CH224Q/A variant.
Update
I ended up ordering a couple more pieces (from a different vendor) and was supplied a slightly different PCB with a SOIC10 labelled “PAK02A”. The device works as intended, however I am unable to determine a manufacturer or datasheet.
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