# CH344Q

**WCH Jiangsu Qin Heng** · USB Converters · LQFP-48(7x7)

CH344Q 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 internal connection; must be left floating (禁止连接，必须悬空). |
| 2 | DSR2 | input | UART2 modem input, data set ready, active low. |
| 3 | RI2 | input | UART2 modem input, ring indicator, active low. |
| 4 | DCD2 | input | UART2 modem input, carrier detect, active low. |
| 5 | XI | input | Crystal oscillator input; 8MHz crystal between XI and XO with about 22pF load capacitors to GND. |
| 6 | XO | output | Crystal oscillator inverting output; 8MHz crystal between XI and XO with about 22pF load capacitor to GND. |
| 7 | RESET | input | External reset input, active low, with internal pull-up (typical 30 ms reset delay after power-up or reset input). |
| 8 | GND | power_in | Common ground; must be connected to the USB bus ground. |
| 9 | VCC | power_in | Positive supply input, 3.0 V to 3.6 V (3.3 V typical); needs external 0.1uF decoupling capacitor. |
| 10 | CTS1/GPIO2 | bidirectional | UART1 modem input, clear to send, active low; also general-purpose GPIO2. |
| 11 | RTS1/GPIO3 | bidirectional | UART1 modem output, request to send, active low; also general-purpose GPIO3. |
| 12 | TXD1 | output | UART1 serial data output; idle state high. |
| 13 | RXD1 | input | UART1 serial data input with internal pull-up. |
| 14 | ACT/CFG/DCD3 | output | USB configured status output, active low, also hardware flow-control enable with internal pull-up; when RTS3 is strapped low at power-up it becomes the UART3 DCD3 carrier-detect input, active low. |
| 15 | TX_S/RI3 | output | Serial transmit status output (200 ms pulse while any UART is sending); when RTS3 is strapped low at power-up it becomes the UART3 RI3 ring-indicator input, active low. |
| 16 | RX_S/DSR3 | output | Serial receive status output (200 ms pulse while any UART is receiving); when RTS3 is strapped low at power-up it becomes the UART3 DSR3 data-set-ready input, active low. |
| 17 | DSR1 | input | UART1 modem input, data set ready, active low. |
| 18 | DTR1/TNOW1/GPIO9 | bidirectional | UART1 modem output DTR, active low, or RS485 TNOW1 direction control per power-up strap (pull-down selects TNOW); also general-purpose GPIO9. |
| 19 | DTR2/TNOW2/GPIO10 | bidirectional | UART2 modem output DTR, active low, or RS485 TNOW2 direction control per power-up strap (pull-down selects TNOW); 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 state high. |
| 22 | RXD2 | input | UART2 serial data input with internal pull-up; input is 5V tolerant (FT). |
| 23 | GND | power_in | Common ground; must be connected to the USB bus ground. |
| 24 | VCC | power_in | Positive supply input, 3.0 V to 3.6 V (3.3 V typical); needs external 0.1uF decoupling capacitor. |
| 25 | RI1 | input | UART1 modem input, ring indicator, active low; input is 5V tolerant (FT). |
| 26 | CTS2/GPIO4 | bidirectional | UART2 modem input, clear to send, active low; also general-purpose GPIO4. |
| 27 | RTS2/GPIO5 | bidirectional | UART2 modem output, request to send, active low; also general-purpose GPIO5. |
| 28 | DCD1/GPIO15 | bidirectional | UART1 modem input, carrier detect, active low; input is 5V tolerant (FT); also general-purpose GPIO15. |
| 29 | DSR0/GPIO14 | bidirectional | UART0 modem input, data set ready, active low; input is 5V tolerant (FT); also general-purpose GPIO14. |
| 30 | TXD0 | output | UART0 serial data output; idle state high. |
| 31 | RXD0 | input | UART0 serial data input with internal pull-up; input is 5V tolerant (FT). |
| 32 | RI0/GPIO13 | bidirectional | UART0 modem input, ring indicator, active low; input is 5V tolerant (FT); also general-purpose GPIO13. |
| 33 | DCD0/GPIO12 | bidirectional | UART0 modem input, carrier detect, active low; input is 5V tolerant (FT); also general-purpose GPIO12. |
| 34 | DTR3/TNOW3/GPIO11 | bidirectional | UART3 modem output DTR, active low, or RS485 TNOW3 direction control per power-up strap (pull-down selects TNOW); input is 5V tolerant (FT); also general-purpose GPIO11. |
| 35 | GND | power_in | Common ground; must be connected to the USB bus ground. |
| 36 | VCC | power_in | Positive supply input, 3.0 V to 3.6 V (3.3 V typical); needs external 0.1uF decoupling capacitor. |
| 37 | TXD3 | output | UART3 serial data output; idle state high. |
| 38 | RXD3 | input | UART3 serial data input; requires an external pull-up resistor (no internal pull-up); input is 5V tolerant (FT). |
| 39 | DTR0/TNOW0/GPIO8 | bidirectional | UART0 modem output DTR, active low, or RS485 TNOW0 direction control per power-up strap (pull-down selects TNOW); input is 5V tolerant (FT); also general-purpose GPIO8. |
| 40 | RTS0/GPIO1 | bidirectional | UART0 modem output, request to send, active low; a pull-down at power-up disables EEPROM parameters and enables built-in defaults; also general-purpose GPIO1. |
| 41 | CTS0/GPIO0 | bidirectional | UART0 modem input, clear to send, active low; input is 5V tolerant (FT); also general-purpose GPIO0. |
| 42 | UD- | bidirectional | USB D- data line connected directly to the USB bus; no series resistor allowed. |
| 43 | UD+ | bidirectional | USB D+ data line connected directly to the USB bus; no series resistor allowed. |
| 44 | TEST | input | Internal test pin; connect to GND through a pull-down resistor (typically 4.7 kΩ) or tie directly to GND. |
| 45 | RTS3/GPIO7 | bidirectional | UART3 modem output, request to send, active low; a pull-down at power-up enables DCD3/RI3/DSR3 on pins 14/15/16; also general-purpose GPIO7. |
| 46 | CTS3/GPIO6 | bidirectional | UART3 modem input, clear to send, active low; input is 5V tolerant (FT); 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, 3.0 V to 3.6 V (3.3 V typical); needs external 0.1uF decoupling 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 |
|---|---|---|---|---|---|---|---|
| Ambient temperature, operating | TA | -40 |  | 85 | ℃ |  | 6 |
| Ambient temperature, storage | TS | -40 |  | 105 | ℃ |  | 6 |
| Supply voltage, absolute maximum | VCC | -0.3 |  | 4 | V | VCC pin supplied, GND pin grounded | 6 |
| Voltage on USB signal pins | VUSB | -0.5 |  | 3.8 | V |  | 6 |
| Voltage on 5V-tolerant serial pins | VIO5V | -0.5 |  | 5.6 | V |  | 6 |
| Voltage on serial and other pins | VUART | -0.5 |  |  | V |  | 6 |
| Supply voltage | VCC | 3 | 3.3 | 3.6 | V | TA=25℃, VCC=3.3V, excluding USB pins; VCC pin supplied, GND grounded | 7 |
| Operating supply current, CH344Q | ICC | 27 | 37 | 50 | mA | TA=25℃, VCC=3.3V, excluding USB pins; normal operation | 7 |
| USB suspend supply current, CH344Q | ISLP | 160 | 230 | 320 | uA | TA=25℃, VCC=3.3V, excluding USB pins; USB suspended | 7 |
| Low-level input voltage | VIL | 0 |  | 0.8 | V | TA=25℃, VCC=3.3V, excluding USB pins | 7 |
| High-level input voltage | VIH | 2 |  |  | V | TA=25℃, VCC=3.3V, excluding USB pins | 7 |
| High-level input voltage, 5V-tolerant pins | VIH5 | 2 |  | 5 | V | TA=25℃, VCC=3.3V, excluding USB pins | 7 |
| Output low voltage | VOL |  |  | 0.4 | V | Single pin sinking 8mA | 7 |
| Equivalent resistance of internal pull-up | RPU | 30 | 40 | 60 | KΩ | TA=25℃, VCC=3.3V, excluding USB pins | 7 |
| Power-on/power-down reset threshold voltage | VPOR | 1.9 | 2.2 | 2.5 | V | TA=25℃, VCC=3.3V, excluding USB pins | 7 |
| ESD withstand voltage, CH344Q | VESD | 3 |  |  | KV | Human body model, non-contact | 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 chip sleep | TWAKE | 0.3 | 0.5 | 4 | mS | TA=25℃, VCC=3.3V | 7 |

## CAD (KiCad official)

- Symbol: `CH344Q`
- Footprint: `Package_QFP:LQFP-48_7x7mm_P0.5mm`
- 3D model: LQFP-48(7x7) (KiCad packages3D, STEP)
- 3D model files: `ch344q-etched.step` / `ch344q-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `ch344q.step` / `ch344q.glb` are the bare package body.

## Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

- **Datasheet:** [WCH Jiangsu Qin Heng datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8618866915339493376) (8 pp, sha256 `9044ddf347f308c1`, retrieved 2026-10-18, 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`, primary `claude-haiku-5-5` (text), consensus `claude-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).

[Datasheet PDF](docs/ch344q-datasheet.pdf)