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CH341A
Public Made by Adomby adom
WCH(Jiangsu Qin Heng) USB ICs, SOP-28-300mil. Pinout cross-checked by two models against the datasheet, KiCad symbol/footprint/3D.
3D Model
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Symbol & Footprint
Schematic Symbol
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PCB Footprint
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Datasheet
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README
markdownCH341A
WCH(Jiangsu Qin Heng) · USB ICs · SOP-28-300mil
CH341A from WCH(Jiangsu Qin Heng), in a SOP-28-300mil. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.
Pinout
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | ACT# | output | USB device configuration status output, active low: high while the USB device is unconfigured, low once configured; may drive an LED through a series current-limiting resistor. |
| 2 | RSTI | input | External reset input, active high with internal pull-down; the chip stays in reset while high and runs about 20 ms of delay after returning low. |
| 3 | IN7 | input | Custom general-purpose input in serial mode; datasheet recommends leaving it unconnected when unused (alternate function AS# in parallel mode). |
| 4 | ROV# | tri_state | Serial receive buffer overflow indicator, active low tri-state output; it should stay high in normal operation (alternate functions AFD# and DS# in printer and parallel modes). |
| 5 | TXD | output | Serial data output of the asynchronous UART; idles high (alternate functions ERR# in printer and parallel modes). |
| 6 | RXD | input | Serial data input of the asynchronous UART with internal pull-up; idles high (alternate function PEMP in printer and parallel modes). |
| 7 | INT# | input | Custom interrupt request input, rising-edge active, with internal pull-up. |
| 8 | IN3 | input | Custom general-purpose input in serial mode; datasheet recommends leaving it unconnected when unused (alternate function SLCT in printer and parallel modes). |
| 9 | V3 | power_in | At 3.3V supply it must be tied to VCC with a 3.0-3.6V input; at 5V supply it needs a 0.01uF to 0.1uF decoupling capacitor. |
| 10 | UD+ | bidirectional | USB D+ data line, connects directly to the USB bus; the chip has the USB pull-up built in. |
| 11 | UD- | bidirectional | USB D- data line, connects directly to the USB bus. |
| 12 | GND | power_in | Common ground, connected directly to the USB bus ground. |
| 13 | XI | input | Crystal oscillator input; CH341A requires an external 12 MHz crystal and load capacitor (or 12 MHz clock input at 11.98-12.02 MHz). |
| 14 | XO | output | Inverting crystal oscillator output; requires a 12 MHz crystal and load capacitor to XO and GND. |
| 15 | CTS# | input | Modem handshake input, clear to send, active low; controlled by the host application, not by the chip. |
| 16 | DSR# | input | Modem handshake input, data set ready, active low; controlled by the host application. |
| 17 | RI# | input | Modem handshake input, ring indicator, active low; controlled by the host application. |
| 18 | DCD# | input | Modem handshake input, carrier detect, active low; controlled by the host application. |
| 19 | OUT# | tri_state | Custom general-purpose output, active low tri-state; the host application sets its state. |
| 20 | DTR# | tri_state | Modem handshake output, data terminal ready, active low tri-state; set by the host application. |
| 21 | RTS# | tri_state | Modem handshake output, request to send, active low tri-state; set by the host application. |
| 22 | SLP# | tri_state | Sleep state output, active low tri-state (alternate function D7 in parallel and printer modes). |
| 23 | SDA | bidirectional | Open-drain configuration data line, with internal pull-up; configures chip function from an external 24Cxx EEPROM or via a direct SCL/SDA strap. |
| 24 | SCL | output | Open-drain configuration clock output with internal pull-up; connects to the SCL pin of an external serial EEPROM. |
| 25 | RDY# | output | Serial receive ready output, active low; high means the chip cannot yet receive data (reset, USB not configured, or receive buffer full). |
| 26 | TNOW | output | Serial transmit in progress indicator, active high; low again after transmission completes. |
| 27 | TEN# | input | Serial transmit enable input, active low, with internal pull-up; when high the chip pauses sending, so it must be low or grounded for the chip to transmit. |
| 28 | VCC | power_in | Positive supply input; 4.0-5.5V with V3 unconnected, or 3.0-3.6V with V3 tied to VCC; requires a 0.1uF decoupling capacitor. |
Key specifications
| Parameter | Value |
|---|---|
| Manufacturer | WCH(Jiangsu Qin Heng) |
| Package | SOP-28-300mil |
| Category | Interface ICs |
| Pins | 28 |
CAD (KiCad official)
- Symbol:
CH341A - Footprint:
Package_SO:SOP-28_8.4x18.16mm_P1.27mm - 3D model: SOP-28-300mil (KiCad packages3D, STEP)
- 3D model files:
ch341a-etched.step/ch341a-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);ch341a.step/ch341a.glbare the bare package body.
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: WCH(Jiangsu Qin Heng) datasheet (12 pp, sha256
8f76a55cf6fbe6fe, retrieved 2026-10-27, tier: lcsc) - Datasheet language: Chinese. Pin names, descriptions, and specs on this page were extracted and translated to English by ds2sf; the linked PDF is the manufacturer original.
- Extractor: parts-factory
2.0.0/extract_pins 0.3, primaryclaude-haiku-5-5(text), consensusclaude-sonnet-5-5(agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish. - CAD: KiCad official libraries (CC-BY-SA 4.0).