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Contents

Pinout
Key specifications
CAD (KiCad official)
Provenance

README

markdown

CH9104L

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

CH9104L 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	GND	power_in	Common ground; must be connected to the USB bus ground line.
2	LOWPWR	bidirectional	USB suspend status output, active low (high in normal operation, low when suspended); if an external pull-down is detected at power-up, the output polarity is switched; tolerates 5 V when used as input.
3	DSR3/GPIO32	bidirectional	UART3 modem input Data Set Ready, active low; general-purpose I/O GPIO32.
4	GND	power_in	Common ground; must be connected to the USB bus ground line.
5	VCC	power_in	Positive supply input, 3.0 V to 3.6 V (typ. 3.3 V); requires an external decoupling capacitor of about 0.1 uF to ground.
6	RTS0/TNOW0/GPIO05	bidirectional	UART0 modem output RTS, active low, or RS485 TNOW transmit/receive control if a pull-down is present at power-up; general-purpose I/O GPIO05; tolerates 5 V when used as input.
7	CTS0/GPIO04	bidirectional	UART0 modem input CTS, active low; general-purpose I/O GPIO04; tolerates 5 V when used as input.
8	TXD1	output	UART1 serial data output; idles high.
9	RXD1	input	UART1 serial data input with internal pull-up; idles high.
10	RTS1/TNOW1/GPIO15	bidirectional	UART1 modem output RTS, active low, or RS485 TNOW transmit/receive control if a pull-down is present at power-up; general-purpose I/O GPIO15; tolerates 5 V when used as input.
11	CTS1/GPIO14	bidirectional	UART1 modem input CTS, active low; general-purpose I/O GPIO14; tolerates 5 V when used as input.
12	DTR1/GPIO13	bidirectional	UART1 modem output DTR, active low; at power-up, a pull-down on this pin enables hardware flow control on all UARTs; general-purpose I/O GPIO13; tolerates 5 V when used as input.
13	DSR1/GPIO12	bidirectional	UART1 modem input Data Set Ready, active low; general-purpose I/O GPIO12.
14	DCD1/GPIO11	bidirectional	UART1 modem input Data Carrier Detect, active low; general-purpose I/O GPIO11.
15	RI1/RWK1/GPIO10	bidirectional	UART1 modem input Ring Indicator, active low; USB wake-up event input 1, active low with internal pull-up; general-purpose I/O GPIO10.
16	DTR0/GPIO03	bidirectional	UART0 modem output DTR, active low; if an external pull-down is present at power-up, the EEPROM configuration is disabled and the chip default parameters are used; general-purpose I/O GPIO03.
17	DSR0/GPIO02	bidirectional	UART0 modem input Data Set Ready, active low; general-purpose I/O GPIO02.
18	VCC	power_in	Positive supply input, 3.0 V to 3.6 V (typ. 3.3 V); requires an external decoupling capacitor of about 0.1 uF to ground.
19	GND	power_in	Common ground; must be connected to the USB bus ground line.
20	DCD0/GPIO01	bidirectional	UART0 modem input Data Carrier Detect, active low; general-purpose I/O GPIO01.
21	RI0/RWK0/GPIO00	bidirectional	UART0 modem input Ring Indicator, active low; USB wake-up event input 0, active low with internal pull-up; general-purpose I/O GPIO00.
22	TXD2	output	UART2 serial data output; idles high.
23	RXD2	input	UART2 serial data input with internal pull-up; idles high.
24	RTS2/TNOW2/GPIO25	bidirectional	UART2 modem output RTS, active low, or RS485 TNOW transmit/receive control if a pull-down is present at power-up; general-purpose I/O GPIO25.
25	CTS2/GPIO24	bidirectional	UART2 modem input CTS, active low; general-purpose I/O GPIO24.
26	DTR2/GPIO23	bidirectional	UART2 modem output DTR, active low; general-purpose I/O GPIO23.
27	DSR2/GPIO22	bidirectional	UART2 modem input Data Set Ready, active low; general-purpose I/O GPIO22.
28	DCD2/GPIO21	bidirectional	UART2 modem input Data Carrier Detect, active low; general-purpose I/O GPIO21.
29	RI2/RWK2/GPIO20	bidirectional	UART2 modem input Ring Indicator, active low; USB wake-up event input 2, active low with internal pull-up; general-purpose I/O GPIO20; tolerates 5 V when used as input.
30	TXD0	output	UART0 serial data output; idles high.
31	RXD0	input	UART0 serial data input with internal pull-up; idles high; tolerates 5 V when used as input.
32	GND	power_in	Common ground; must be connected to the USB bus ground line.
33	VCC	power_in	Positive supply input, 3.0 V to 3.6 V (typ. 3.3 V); requires an external decoupling capacitor of about 0.1 uF to ground.
34	DCD3/GPIO31	bidirectional	UART3 modem input Data Carrier Detect, active low; general-purpose I/O GPIO31; tolerates 5 V when used as input.
35	CFG0	input	Remote wake-up and USB power mode configuration pin 0; tolerates 5 V when used as input.
36	CFG1	input	Remote wake-up and USB power mode configuration pin 1; tolerates 5 V when used as input.
37	RI3/RWK3/GPIO30	bidirectional	UART3 modem input Ring Indicator, active low; USB wake-up event input 3, active low with internal pull-up; general-purpose I/O GPIO30; tolerates 5 V when used as input.
38	TXD3	output	UART3 serial data output; idles high.
39	RXD3	input	UART3 serial data input with internal pull-up; idles high; tolerates 5 V when used as input.
40	GND	power_in	Common ground; must be connected to the USB bus ground line.
41	GND	power_in	Common ground; must be connected to the USB bus ground line.
42	UD-	bidirectional	USB D- data line, connected directly to the USB bus; no series resistor may be added.
43	UD+	bidirectional	USB D+ data line, connected directly to the USB bus; no series resistor may be added.
44	NC	unconnected	No connection; must be left floating.
45	VCC	power_in	Positive supply input, 3.0 V to 3.6 V (typ. 3.3 V); requires an external decoupling capacitor of about 0.1 uF to ground.
46	RTS3/TNOW3/GPIO35	bidirectional	UART3 modem output RTS, active low, or RS485 TNOW transmit/receive control if a pull-down is present at power-up; general-purpose I/O GPIO35; tolerates 5 V when used as input.
47	CTS3/GPIO34	bidirectional	UART3 modem input CTS, active low; general-purpose I/O GPIO34; tolerates 5 V when used as input.
48	DTR3/GPIO33	bidirectional	UART3 modem output DTR, active low; general-purpose I/O GPIO33; tolerates 5 V when used as input.

Key specifications

Parameter	Value
Manufacturer	WCH Jiangsu Qin Heng
Package	LQFP-48(7x7)
Category	Interface
Pins	48

CAD (KiCad official)

Symbol: CH9104L
Footprint: Package_QFP:LQFP-48_7x7mm_P0.5mm
3D model: LQFP-48(7x7) (KiCad packages3D, STEP)
3D model files: ch9104l-etched.step / ch9104l-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); ch9104l.step / ch9104l.glb are the bare package body.

Provenance

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

Datasheet: WCH Jiangsu Qin Heng datasheet (7 pp, sha256 4c6ffbf98d4337ee, 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, 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