| Pin | Symbol | Type | Function (EN) |
|---|---|---|---|
| 1 | IO1 | I/O | General Purpose Digital I/O Pin IO1 |
| 2 | IO2 | I/O | General Purpose Digital I/O Pin IO2 |
| 3 | 3V3 | Power | 3.3V Main Power Supply Rail (3.0V ~ 3.6V) |
| 4 | NC | NC | No Connect (Leave Floating) |
| 5 | PC1 I/O/A PC1 | I/O | Multiplexed I/O & Peripheral Pin PC1 I/O/A PC1 (General) |
| 6 | PA0 I/O/A PA0 | I/O | Multiplexed I/O & Peripheral Pin PA0 I/O/A PA0 (UART) |
| 7 | GND P GND | GND | Ground Reference Pin (GND P GND) |
| 8 | IO0 | I/O | GPIO0 / RTC_GPIO0 (Chip Boot Mode Strapping Pin) |
| 9 | V P VDD DD | Power | Power Supply Input (V P VDD DD — 2V~5.5V) |
| 10 | PA4 I/O/A PA4 | I/O | Multiplexed I/O & Peripheral Pin PA4 I/O/A PA4 (UART) |
| 11 | IO6 | I/O | GPIO6 / RTC_GPIO6 / TOUCH6 / ADC1_CH5 |
| 12 | PA6 I/O/A PA6 | I/O | Multiplexed I/O & Peripheral Pin PA6 I/O/A PA6 (UART, SPI) |
| 13 | PB11/T1C3/T2C1N_/RX1 | I/O | Multiplexed I/O & Peripheral Pin PB11/T1C3/T2C1N_/RX1 (General) |
| 14 | IO16 | I/O | GPIO16 / RTC_GPIO16 / U0CTS / ADC2_CH5 / XTAL_32K_N |
| 15 | PB12/T1C4_/T2C2N_ | I/O | Multiplexed I/O & Peripheral Pin PB12/T1C4_/T2C2N_ (General) |
| 16 | IO18 | I/O | GPIO18 / RTC_GPIO18 / U1RXD / ADC2_CH7 / CLK_OUT3 |
| 17 | IO8 | I/O | GPIO8 / RTC_GPIO8 / TOUCH8 / ADC1_CH7 / SUBSPICS1 |
| 18 | IO19 | I/O | GPIO19 / RTC_GPIO19 / USB_D- / U1RTS / ADC2_CH8 |
| 19 | IO20 | I/O | GPIO20 / RTC_GPIO20 / USB_D+ / U1CTS / ADC2_CH9 |
| 20 | IO9 | I/O | GPIO9 / RTC_GPIO9 / TOUCH9 / ADC1_CH8 / FSPIHD |
| 21 | GND | GND | Ground Reference Pin (GND) |
CH32X035 / CH32X033 (QFN-20-EP(3x3))
CH32X035 / CH32X033 (QFN-28(4X4))
CH32X035 / CH32X033 (LQFP-48(7x7))
| Designator / Replacement MPN | Value / Package | Function & PCB Layout Rule |
|---|---|---|
| N/A BOM | Per application circuit QFN-20-EP(3x3) | Size power & signal trace widths for rated load current following IPC-2221 clearance rules. |
Manufactured by WCH, the CH32X035F8U6 is housed in a QFN-20-EP(3x3) package with 21 pins and a 0.50 mm lead pitch, supporting a VCC supply range of 2V~5.5V. Key pins include: 1 (IO1: General Purpose Digital I/O Pin IO1), 2 (IO2: General Purpose Digital I/O Pin IO2), 3 (3V3: 3.3V Main Power Supply Rail (3.0V ~ 3.6V)), 4 (NC: No Connect (Leave Floating)), 5 (PC1 I/O/A PC1: Multiplexed I/O & Peripheral Pin PC1 I/O/A PC1 (General)), 6 (PA0 I/O/A PA0: Multiplexed I/O & Peripheral Pin PA0 I/O/A PA0 (UART)).
Normalized from the official datasheet mechanical drawing per IPC-7351B (Density Level B Nominal), CH32X035F8U6 (QFN-20-EP(3x3)) has a nominal body envelope of 3.00 × 3.00 mm, pitch e = 0.50 mm, and 21 copper pads plus a central exposed thermal pad (EPAD) of 1.70 × 1.70 mm with a 60% IPC-7525 windowed solder paste grid.
You can download the verified open-hardware (CERN-OHL-P-2.0) CAD library bundle for CH32X035F8U6 (WCH, QFN-20-EP(3x3)) directly on this page, including KiCad 8 Footprints (.kicad_mod), Schematic Symbols (.kicad_sym), Autodesk Fusion 360 / Eagle (.lbr), and 3D STEP AP214 / WebGL GLB models.
| Pin # | Signal Name | Electrical Type | Functional Description & Design Notes |
|---|---|---|---|
| 1 | IO1 | Digital_IO | General Purpose Digital I/O Pin IO1 |
| 2 | IO2 | Digital_IO | General Purpose Digital I/O Pin IO2 |
| 3 | 3V3 | Power_In | 3.3V Main Power Supply Rail (3.0V ~ 3.6V) |
| 4 | NC | No_Connect | No Connect (Leave Floating) |
| 5 | PC1 I/O/A PC1 | Digital_IO | Signal terminal PC1 I/O/A PC1 (I/O, 2V~5.5V domain). Multiplexed alternate functions: PC1 I/O/A PC1. Supported peripheral buses: General. |
| 6 | PA0 I/O/A PA0 | Digital_IO | Signal terminal PA0 I/O/A PA0 (I/O, 2V~5.5V domain). Multiplexed alternate functions: PA0 I/O/A PA0. Supported peripheral buses: UART. |
| 7 | GND P GND | GND | 0V electrical ground return terminal (GND P GND) for internal core logic, I/O drivers, and analog sub-blocks. |
| 8 | IO0 | Digital_IO | GPIO0 / RTC_GPIO0 (Chip Boot Mode Strapping Pin) |
| 9 | V P VDD DD | Power_In | Primary positive power supply input (V P VDD DD) operating in the 2V~5.5V domain (Max rating: 5.5V). |
| 10 | PA4 I/O/A PA4 | Digital_IO | Signal terminal PA4 I/O/A PA4 (I/O, 2V~5.5V domain). Multiplexed alternate functions: PA4 I/O/A PA4. Supported peripheral buses: UART. |
| 11 | IO6 | Digital_IO | GPIO6 / RTC_GPIO6 / TOUCH6 / ADC1_CH5 |
| 12 | PA6 I/O/A PA6 | Digital_IO | Signal terminal PA6 I/O/A PA6 (I/O, 2V~5.5V domain). Multiplexed alternate functions: PA6 I/O/A PA6. Supported peripheral buses: UART, SPI. |
| 13 | PB11/T1C3/T2C1N_/RX1 | Digital_IO | Signal terminal PB11/T1C3/T2C1N_/RX1 (I/O, 2V~5.5V domain). Multiplexed alternate functions: PB11/T1C3/T2C1N_/RX1. Supported peripheral buses: General. |
| 14 | IO16 | Digital_IO | GPIO16 / RTC_GPIO16 / U0CTS / ADC2_CH5 / XTAL_32K_N |
| 15 | PB12/T1C4_/T2C2N_ | Digital_IO | Signal terminal PB12/T1C4_/T2C2N_ (I/O, 2V~5.5V domain). Multiplexed alternate functions: PB12/T1C4_/T2C2N_. Supported peripheral buses: General. |
| 16 | IO18 | Digital_IO | GPIO18 / RTC_GPIO18 / U1RXD / ADC2_CH7 / CLK_OUT3 |
| 17 | IO8 | Digital_IO | GPIO8 / RTC_GPIO8 / TOUCH8 / ADC1_CH7 / SUBSPICS1 |
| 18 | IO19 | Digital_IO | GPIO19 / RTC_GPIO19 / USB_D- / U1RTS / ADC2_CH8 |
| 19 | IO20 | Digital_IO | GPIO20 / RTC_GPIO20 / USB_D+ / U1CTS / ADC2_CH9 |
| 20 | IO9 | Digital_IO | GPIO9 / RTC_GPIO9 / TOUCH9 / ADC1_CH8 / FSPIHD |
| 21 | GND | GND | 0V electrical ground return terminal (GND) for internal core logic, I/O drivers, and analog sub-blocks. |