CH224 is a chip family specializing on negotiating fixed output voltages from a variety of USB power protocols, including USB PD. The basic CH224K is well suited for use cases where you need one of the pre-defined voltage steps (5V, 9V, 12V, 15V, 20V) at a maximum of 100W.
Newer family members like the CH224A also support PD3.2 EPS (140W at a maximum voltage of 48V), and CH224Q also supports PPS and AVS for delivering adjustable voltages in 20/100mV increments.
Overview
CH224 manages USB Power Delivery (PD) negotiation, ensuring your device receives the voltage and current it needs.
- CH224K:
10-pin CH224K is the most popular family member found on many simple and affordable USB trigger boards: it supports USB PD3.0/2.0 and BC 1.2, can request five fixed voltages (5V, 9V, 12V, 15V, and 20V) at up to 100W, and includes an optional simple-to-use digital interface that makes it easy to interface with external microcontrollers.
-
CH224A:
modern drop-in replacement for CH224K with additional USB PD 3.2 EPR support for voltages of up to 48V at a maximum power of 140W. I2C is supported as another interface option.Unfortunately, CH224A does not support PPS and AVS (adjustable voltage). -
CH224Q:
Adds support for PPS and AVS which allows voltage selection in 20mV/100mV increments.
Variant Overview
| Feature / Model | CH221K | CH224K | CH224D | CH224A | CH224Q |
|---|---|---|---|---|---|
| PD Version | PD3.0/2.0 | PD3.0/2.0 | PD3.0/2.0 | PD3.2 EPR | PD3.2 EPR AVS PPS |
| Max Voltage | 20V | 20V | 20V | 48V | 48V |
| Adjustable Voltage | ❌ | ❌ | ❌ | ❌ | ✔️ |
| Max Power | 100W | 100W | 100W | 140W | 140W |
| Protocols | PD | PD, BC1.2, AFC, FCP, QC2.0, etc. | PD, BC1.2, AFC, FCP, QC2.0, etc. | PD, BC1.2, EPR, etc. | PD, BC1.2, EPR, AVS, PPS, etc. |
| Voltage Config | - Resistor | - Resistor - GPIO |
- Resistor - GPIO |
-Resistor - GPIO - I2C |
-Resistor - GPIO - I2C |
| I2C Support (400kHz) | ❌ | ❌ | ❌ | ✔️ | ✔️ |
| E-Marker Simulation | ❌ | ✔️ | ✔️ | ✔️ | ✔️ |
Max Voltage on pins CFG2/CFG3 |
❌ | 3.7V | 5V | 5V | 5V |
| Special Pins | ❌ | ❌ | GATE (NMOS), ISP/ISN (current) | ❌ | ❌ |
| Package | SOT23-6L | ESSOP10 | QFN20, ESSOP10 | ESSOP10 | QFN20 |
| Use Case | Consumer Devices | Trigger Boards | Trigger Boards | High-Power Trigger Boards | High-Power Trigger Boards |
Trigger Boards
Trigger boards typically use the affordable 10-pin CH224K found in many USB Trigger Boards.
It is likely that CH224K will be replaced by the pin-compatible CH224A in the near future, increasing the power from 100W to 140W, and the maximum voltage from 20V to 48V, and adding I2C support for external microcontrollers.
| Feature | CH224K | CH224A |
|---|---|---|
| max. Voltage | 20V | 48V |
| max. Power | 100W | 140W |
| I2C | no | yes |
Note that CH224A does not support adjustable voltage (PPS and AVR). Only CH224Q allows for freely adjustable voltages in 20/100mV increments.
Use Cases
USB trigger boards play an important role in many DIY projects, for example:
- Custom Power Adapters: Power portable soldering irons and other high-demand devices at 20V and up to 100W from a USB power bank.
- Car Adapter: Add a trigger board to a 12V cigarette lighter socket, and run devices originally designed for automotive use from a USB power source.
- USB PD Tester: Control the trigger chip from an external microcontroller to automatically test USB power sources and identify the voltages it can deliver.
- Lab Bench Power Supply: Create a (simple) lab bench power supply that can be powered by a USB charger and delivers one of the pre-defined voltages on key press.
Voltage Selection
The trigger voltage can be set in three ways:
| Method | CH221K | CH224K/D | CH224A/Q |
|---|---|---|---|
Resistor (CFG1) |
✔️ | ✔️ | ✔️ |
Level (CFG2, CFG3) |
❌ | ✔️ | ✔️ |
| I2C | ❌ | ❌ | ✔️ |
Resistance Configuration
In this mode, a single resistor is connected to CFG1 and GND.
| Resistance on CFG1 to GND | Request-voltage |
|---|---|
| 6.8KΩ | 9V |
| 24KΩ | 12V |
| 56KΩ | 15V |
| NC (CH224K/D) / 120KΩ (CH224A/Q) | 20V |
| 210KΩ (CH224A/Q only) | 28V |
CFG2 and CFG3 are not used.
With CH224K/D, when
CFG1,CFG2, andCFG3are left unconnected, the chip defaults to 20V.
CH221K
CH221K is the only chip variant that works differently: the pin is called CFG (not CFG1), the resistor must connect to VDD (not GND), and the resistor values are different:
| Resistance on CFG to VDD | Request-voltage |
|---|---|
| 10KΩ | 5V |
| 20KΩ | 9V |
| 47KΩ | 12V |
| 100KΩ | 15V |
| 200KΩ | 20V |
Level Configuration Mode
In this mode, all three CFGx pins are used. when CFG1 is pulled low, this digital (“level”) mode is enabled: the states of CFG2 and CFG3 now determine the trigger voltage:
| CFG1 | CFG2 | CFG3 | Request-voltage |
|---|---|---|---|
| 1 | - | - | 5V |
| 0 | 0 | 0 | 9V |
| 0 | 0 | 1 | 12V |
| 0 | 1 | 1 | 15V |
| 0 | 1 | 0 | 20V |
Level configuration mode is a simple digital protocol for external microcontrollers to control the trigger voltage, requiring just two GPIOs:
- Maximum Pin Voltage:
- CH224K:
CFG1,CFG2andCFG3must not exceed 3.7V -
all other:
CFG1must not exceed 3.7V (use a 2KΩ resistor in series for 5V systems)CFG2andCFG3must not exceed 5.0V
- CH224K:
- External Pullup/Pulldown Resistors:
- CH224K/D:
add external pullup or pulldown resistors to setCFG2andCFG3to defined default states. Else, while the MCU is still booting, the GPIOs may be in a floating (random) state and can accidentally request high trigger voltages that may damage connected devices. - CH224A/Q:
uses built-in pull-up resistors onCFG2andCFG3defaulting to 20V output when not actively configured otherwise.
- CH224K/D:
- Disabling Level Control:
pull upCFG1toVHVthrough 100KΩ resistor
I2C Interface
CH224A/Q support the I2C interface. Using this interface is mandatory for accessing advanced functionality:
- CH224A:
- I2C status register (
0x09) - voltage control register (
0x0A, only fixed voltage steps) - current data register (
0x50, maximum available current).
- I2C status register (
- CH224Q adds:
- AVS voltage configuration register (
0x51,0x52, adjustable voltage above 15V in 100mV increments) - PPS voltage configuration register (
0x53, adjustable voltage up to 15V in 25mV increments) - PD power data register (
0x60-0x8F, complete power information)
- AVS voltage configuration register (
For I2C details including the register map, see the datasheet.
E-Marker Simulation
With USB PD protocols, power levels above 60W or voltages above 20V are only enabled when the USB-C cable contains an e-marker chip certifying the cable for these power levels. This is a critical safety feature.
CH224 can simulate e-markers, allowing the use of any USB cable at high power. If you enable e-marker simulation, you lose the built-in cable safety protection and must ensure the cable can safely carry the required current.
To enable e-marker simulation, connect CC2 to GND using a 1KΩ resistor.
Safety Features
- OVP: over-voltage protection
- OTP: over-temperature protection
- OVD: output-voltage detection
Materials
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(content created Jun 29, 2025)