component
CH344L
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WCH Jiangsu Qin Heng USB Converters, LQFP-48(7x7). 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
markdownCH344L
WCH Jiangsu Qin Heng · USB Converters · LQFP-48(7x7)
CH344L from WCH Jiangsu Qin Heng, in a LQFP-48(7x7). 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 | NC | unconnected | No connect; must be left floating on CH344L. |
| 2 | CFG2 | input | CH344L TNOW/DTR function select: high or floating at power-up makes all DTRx/TNOWx pins TNOW, low makes them DTR, and individual ports can be set to TNOW with a 4.7kΩ pull-down on their DTRx/TNOWx pin. |
| 3 | NC | unconnected | No connect; must be left floating on CH344L. |
| 4 | NC | unconnected | No connect; must be left floating on CH344L. |
| 5 | XI | input | Crystal oscillator input; an 8MHz crystal with ~22pF load capacitors to GND is recommended, and CH344L may use its internal clock if the crystal is omitted at the cost of larger baud-rate error. |
| 6 | XO | output | Crystal oscillator inverting output; connects to the other side of the 8MHz crystal with its ~22pF load capacitor to GND. |
| 7 | RESET | input | External reset input, active low, with internal pull-up (RPU typ. 40kΩ, range 30-60kΩ). |
| 8 | GND | power_in | Common ground; must be connected to the USB bus ground. |
| 9 | VCC | power_in | Positive supply input at 3.0-3.6V (3.3V typical), decoupled to GND with a ~0.1µF capacitor. |
| 10 | CTS1/GPIO2 | input | UART1 modem input CTS, active low, also usable as general-purpose GPIO2 and for hardware flow control. |
| 11 | RTS1/GPIO3 | output | UART1 modem output RTS, active low, also general-purpose GPIO3. |
| 12 | TXD1 | output | UART1 serial data output, idle high. |
| 13 | RXD1 | input | UART1 serial data input with internal pull-up. |
| 14 | ACT | output | USB configuration complete status output, active low. |
| 15 | TX_S | output | Serial data transmit status output; outputs a 200ms-period pulse while any UART is transmitting. |
| 16 | RX_S | output | Serial data receive status output; outputs a 200ms-period pulse while any UART is receiving. |
| 17 | NC | unconnected | No connect; must be left floating on CH344L. |
| 18 | DTR1/TNOW1/GPIO9 | bidirectional | UART1 modem output DTR (active low) or RS485 TNOW1 transmit/receive control, selected at power-up by CFG2; also general-purpose GPIO9. |
| 19 | DTR2/TNOW2/GPIO10 | bidirectional | UART2 modem output DTR (active low) or RS485 TNOW2 transmit/receive control, selected at power-up by CFG2; also general-purpose GPIO10. |
| 20 | GND | power_in | Common ground; must be connected to the USB bus ground. |
| 21 | TXD2 | output | UART2 serial data output, idle high. |
| 22 | RXD2 | input | UART2 serial data input with internal pull-up. |
| 23 | GND | power_in | Common ground; must be connected to the USB bus ground. |
| 24 | VCC | power_in | Positive supply input at 3.0-3.6V (3.3V typical), decoupled to GND with a ~0.1µF capacitor. |
| 25 | NC | unconnected | No connect; must be left floating on CH344L. |
| 26 | CTS2/GPIO4 | input | UART2 modem input CTS, active low, also general-purpose GPIO4. |
| 27 | RTS2/GPIO5 | output | UART2 modem output RTS, active low, also general-purpose GPIO5. |
| 28 | NC | unconnected | No connect; must be left floating on CH344L. |
| 29 | TXD3 | output | UART3 serial data output, idle high. |
| 30 | TXD0 | output | UART0 serial data output, idle high. |
| 31 | RXD0 | input | UART0 serial data input with internal pull-up. |
| 32 | UD- | bidirectional | USB D- data line, connected directly to the USB bus D- with no series resistor allowed. |
| 33 | UD+ | bidirectional | USB D+ data line, connected directly to the USB bus D+ with no series resistor allowed. |
| 34 | NC | unconnected | No connect; must be left floating on CH344L. |
| 35 | GND | power_in | Common ground; must be connected to the USB bus ground. |
| 36 | VCC | power_in | Positive supply input at 3.0-3.6V (3.3V typical), decoupled to GND with a ~0.1µF capacitor. |
| 37 | NC | unconnected | No connect; must be left floating on CH344L. |
| 38 | CFG | input | Hardware flow control enable, active low, with internal pull-up. |
| 39 | DTR0/TNOW0/GPIO8 | bidirectional | UART0 modem output DTR (active low) or RS485 TNOW0 transmit/receive control, selected at power-up by CFG2; also general-purpose GPIO8. |
| 40 | RTS0/GPIO1 | output | UART0 modem output RTS, active low, also general-purpose GPIO1; if pulled low at power-up, internal EEPROM configuration is disabled and chip default parameters are used. |
| 41 | CTS0/GPIO0 | input | UART0 modem input CTS, active low, also general-purpose GPIO0. |
| 42 | RXD3 | input | UART3 serial data input; requires an external pull-up resistor on CH344L. |
| 43 | DTR3/TNOW3/GPIO11 | bidirectional | UART3 modem output DTR (active low) or RS485 TNOW3 transmit/receive control, selected at power-up by CFG2; also general-purpose GPIO11. |
| 44 | TEST | input | Internal test pin; connect to GND through a pull-down (typ. 4.7kΩ) or tie directly to GND. |
| 45 | RTS3/GPIO7 | output | UART3 modem output RTS, active low, also general-purpose GPIO7. |
| 46 | CTS3/GPIO6 | input | UART3 modem input CTS, active low, also general-purpose GPIO6. |
| 47 | GND | power_in | Common ground; must be connected to the USB bus ground. |
| 48 | VCC | power_in | Positive supply input at 3.0-3.6V (3.3V typical), decoupled to GND with a ~0.1µF capacitor. |
Key specifications
| Parameter | Value |
|---|---|
| Manufacturer | WCH Jiangsu Qin Heng |
| Package | LQFP-48(7x7) |
| Category | Interface |
| Pins | 48 |
Electrical characteristics
Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).
| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Supply voltage (VCC) | VCC | 3 | 3.3 | 3.6 | V | TA=25℃，VCC=3.3V，不含 USB 引脚 | 7 |
| Operating supply current, CH344L | ICC | 12 | 18 | 24 | mA | TA=25℃，VCC=3.3V，不含 USB 引脚 | 7 |
| USB suspend supply current, CH344L | ISLP | 200 | 450 | 600 | uA | TA=25℃，VCC=3.3V，不含 USB 引脚 | 7 |
| Low-level input voltage | VIL | 0 | 0.8 | V | TA=25℃，VCC=3.3V，不含 USB 引脚 | 7 | |
| High-level input voltage | VIH | 2 | V | TA=25℃，VCC=3.3V，不含 USB 引脚 | 7 | ||
| High-level input voltage, 5V-tolerant pins | VIH5 | 2 | 5 | V | TA=25℃，VCC=3.3V，不含 USB 引脚 | 7 | |
| Output low voltage | VOL | 0.4 | V | 单个引脚吸入 8mA 电流 | 7 | ||
| Internal pull-up equivalent resistance | RPU | 30 | 40 | 60 | KΩ | TA=25℃，VCC=3.3V，不含 USB 引脚 | 7 |
| Power-on/power-down reset threshold voltage | VPOR | 1.9 | 2.2 | 2.5 | V | TA=25℃，VCC=3.3V，不含 USB 引脚 | 7 |
| ESD withstand voltage, human body model, non-contact (CH344L) | VESD | 3 | KV | 人体模型，非接触式 | 7 | ||
| Internal clock error, TA=0℃ to 70℃ (CH344L) | FD | -1.5 | 0.8 | 1.5 | % | TA=0℃～70℃ | 7 |
| Internal clock error, TA=-40℃ to 85℃ (CH344L) | FD | -2 | 1.5 | 2 | % | TA=-40℃～85℃ | 7 |
| Reset delay after power-on or external reset | TRSTD | 15 | 30 | 45 | mS | TA=25℃，VCC=3.3V | 7 |
| USB auto-suspend detection time | TSUSP | 3 | 5 | 9 | mS | TA=25℃，VCC=3.3V | 7 |
| Wake-up completion time after sleep | TWAKE | 0.3 | 0.5 | 4 | mS | TA=25℃，VCC=3.3V | 7 |
| Operating ambient temperature | TA | -40 | 85 | ℃ | 工作时的环境温度 | 6 | |
| Storage ambient temperature | TS | -40 | 105 | ℃ | 储存时的环境温度 | 6 | |
| Supply voltage (VCC pin, GND grounded) | VCC | -0.3 | 4 | V | VCC 引脚供电，GND 引脚接地 | 6 | |
| Voltage on USB signal pins | VUSB | -0.5 | 3.8 | V | USB 信号引脚 | 6 | |
| Voltage on 5V-tolerant serial pins | VIO5V | -0.5 | 5.6 | V | 耐受 5V 的串口引脚 | 6 |
CAD (KiCad official)
- Symbol:
CH344L - Footprint:
Package_QFP:LQFP-48_7x7mm_P0.5mm - 3D model: LQFP-48(7x7) (KiCad packages3D, STEP)
- 3D model files:
ch344l-etched.step/ch344l-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);ch344l.step/ch344l.glbare the bare package body.
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: WCH Jiangsu Qin Heng datasheet (8 pp, sha256
9044ddf347f308c1, retrieved 2026-10-19, 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).