Part: CH343P — WCH

Type: USB to High-Speed Asynchronous Serial Port Adapter Chip

Description: A USB bus adapter chip that implements USB to high-speed asynchronous serial port, providing common MODEM handshake signals, supporting baud rates from 50bps to 6Mbps, and flexible I/O voltage from 1.8V to 5V.

Operating Conditions:

• Supply voltage (VDD5): 3–5.5 V
• I/O supply voltage (VIO): 1.7–5.5 V
• Operating temperature: -40 to 85 °C
• Baud rate: 50bps to 6Mbps

Absolute Maximum Ratings:

• Max supply voltage (VDD5): 6.0 V
• Max I/O supply voltage (VIO): 6.0 V
• Max storage temperature: 125 °C

Key Specs:

• VDD5 operating voltage: 4–5.5 V (V3 not connected to VDD5), 3–3.6 V (V3 connected to VDD5)
• VIO operating voltage: 1.7–5.5 V
• VDD5 or V3 operating current: 3 mA (Typ), 15 mA (Max)
• USB suspend current (VDD5=5V): 0.09 mA (Typ), 0.16 mA (Max)
• VIO suspend current (no I/O load): 0.002 mA (Typ), 0.05 mA (Max)
• Internal LDO external load capability: 10 mA (Max)
• Serial port transmit baud rate error: < 1.6%
• Serial port receive baud rate error: < 4%

Features:

• Full-speed USB device interface, compatible with USB V2.0.
• Built-in firmware, emulates standard serial port.
• Supports driver-free CDC class drivers or multi-functional high-speed VCP vendor drivers.
• Hardware full-duplex serial port, built-in independent transmit/receive buffers.
• Serial port supports 5, 6, 7, or 8 data bits, and various parity options.
• Supports common MODEM handshake signals: RTS, DTR, DCD, RI, DSR, CTS.
• Supports CTS and RTS hardware automatic flow control.
• Supports half-duplex, provides TNOW status for RS485 switching.
• USB side supports 5V and 3.3V power supply voltages.
• Serial port I/O is independently powered, supports 5V, 3.3V, 2.5V, 1.8V power supply voltages, supports anti-reverse current.
• Built-in power-on reset, built-in clock, no external crystal oscillator required.
• CH343P has built-in EEPROM, configurable chip VID, PID, maximum current value, manufacturer and product information strings.
• Chip has built-in Unique ID (USB Serial Number).

Applications:

• Expanding asynchronous serial ports for computers.
• Upgrading ordinary serial devices or MCUs to the USB bus.
• Providing RS232, RS485, RS422 interfaces via external level shifters.
• Multi-mode MCU downloads.

Package:

• QFN16_3X3 (16-pin, 3x3mm)
• SOP16 (16-pin, 3.9mm body width)
• ESSOP10 (10-pin, 3.9mm body width)

CH343P TQFN-16-EP(3x3) Pinout

Pin Number	Pin Name	Type	Description
1	UD+	USB Signal	Directly connected to the D+ data line of the USB bus, no additional series resistor.
2	UD-	USB Signal	Directly connected to the D- data line of the USB bus, no additional series resistor.
3	VDD5	Power	Positive power input for the voltage regulator, requires an external decoupling capacitor.
4	TXD	Output	Serial data output, high level in idle state.
5	RXD	Input	Serial data input, built-in pull-up resistor.
6	V3	Power	Internal voltage regulator output and core/USB power input. Connect to VDD5 for external power when VDD5 voltage is less than 3.6V. Connect an external decoupling capacitor when VDD5 voltage is greater than 3.6V.
7	UD+	USB Signal	Directly connected to the D+ data line of the USB bus, no additional series resistor.
8	UD-	USB Signal	Directly connected to the D- data line of the USB bus, no additional series resistor.
9	VBUS	Input	USB bus VBUS status detection input, built-in pull-down resistor.
10	ACT#	Output	USB configuration complete status output, low active, invalid during suspend.
11	DCD	Input	MODEM handshake input signal, Carrier Detect, low active.
12	DTR/TNOW	Output	MODEM handshake output signal, Data Terminal Ready, low active. If an external pull-down resistor is detected during power-on, it switches to serial port transmitting status indicator, high active.
13	RTS	Output	MODEM handshake output signal, Request To Send, low active.
14	DSR	Input	MODEM handshake input signal, Data Set Ready, low active.
15	CTS	Input	MODEM handshake input signal, Clear To Send, low active.
16	RI	Input	MODEM handshake input signal, Ring Indicator, low active.
0 (EP)	GND	Power	Common ground, needs to be connected to the USB bus ground. Exposed pad (EP).

Notes

• Pin 0 (EP): Exposed pad on the bottom of the TQFN-16-EP package; electrically equivalent to pins 2 and should be soldered for thermal and electrical connection.
• VIO Pin: CH343P does not have a dedicated VIO pin in the TQFN-16 package. VIO power must be supplied externally through the same supply as the MCU/peripheral I/O.
• DTR/TNOW Dual Function: Pin 12 operates as DTR (MODEM output, low active) by default. If an external 4.7kΩ pull-down resistor is connected during power-on/reset, the pin switches to TNOW (transmit status indicator, high active) for half-duplex/RS485 applications.
• EEPROM: CH343P includes built-in EEPROM for configurable VID, PID, maximum current, and product information strings.
• Power Supply: VDD5 supports 4–5.5V (when V3 is externally regulated) or 3–3.6V (when V3 is connected to VDD5). V3 requires external 0.1µF decoupling capacitor.

Name	Parameter Description	Min	Max	Unit
TA	Ambient Temperature during Operation	-40	85	°C
TS	Ambient Temperature during Storage	-55	125	°C
VDD5	USB Power Supply Voltage (VDD5 pin powered, GND pin grounded)	-0.5	6.0	V
VIO	Serial Port I/O Power Supply Voltage (VIO pin powered, GND pin grounded)	-0.5	6.0	V
VVBUS	Voltage on VBUS pin	-0.5	6.5	V
VUSB	Voltage on USB Signal Pins	-0.5	V3+0.5	V
VUART	Voltage on Serial Port and Other Pins	-0.5	VIO+0.5	V

• 6.2. Electrical Parameters (Test Conditions: TA=25 °C, VDD5=5V or VDD5=V3=3.3V, VIO=1.8V ~ 5V, excluding USB pins)

Name	Parameter Description	Parameter Description	Parameter Description	Min	Typ	Max	Unit
VDD5	USB Side	V3 pin not connected to VDD5, V3 connected to capacitor	V3 pin not connected to VDD5, V3 connected to capacitor	4	5	5.5	V
VDD5	Power Supply Voltage	V3 pin connected to VDD5, VDD5=V3	V3 pin connected to VDD5, VDD5=V3	3	3.3	3.6	V
VIO	VIO Power Supply Voltage for Serial Port and Other I/O	VIO Power Supply Voltage for Serial Port and Other I/O	VIO Power Supply Voltage for Serial Port and Other I/O	1.7	5	5.5	V
IVDD	VDD5 or V3 Power Supply Current during Operation	VDD5 or V3 Power Supply Current during Operation	VDD5 or V3 Power Supply Current during Operation		3	15	mA
IVIO	VIO Power Supply Current during Operation (depends on I/O load)	VIO Power Supply Current during Operation (depends on I/O load)	VIO Power Supply Current during Operation (depends on I/O load)		0	( 10 )	mA
ISLP	USB	VDD5 Power Supply =5V	VDD5 Power Supply =5V		0.09	0.16	mA
ISLP	During Suspend	VDD5=V3 Power Supply =3.3V	VDD5=V3 Power Supply =3.3V		0.085	0.15	mA
ISLP	Power Supply Current	VIO Power Supply, no I/O load / pull-up	VIO Power Supply, no I/O load / pull-up		0.002	0.05	mA
ILDO	External Load Capability of Internal Power Regulator	External Load Capability of Internal Power Regulator	External Load Capability of Internal Power Regulator			10	mA
VIL			VIO=5V	0		1.5	V
VIL	Low-Level Input Voltage	Low-Level Input Voltage	VIO=3.3V	0		0.9	V
VIL			VIO=1.8V	0		0.5	V
VIH			VIO=5V	2.5		VIO	V
VIH	High-Level Input Voltage	High-Level Input Voltage	VIO=3.3V	1.9		VIO	V
VIH			VIO=1.8V	1.3		VIO	V
VIHVBS	VBUS Pin High-Level Voltage	VBUS Pin High-Level Voltage	VIO=1.8V ~ 5V	1.7		5.8	V
VOL	Low-Level Output Voltage	VIO=5V, sinking 15mA current	VIO=5V, sinking 15mA current		0.4	0.5	V
VOL		VIO=3.3V, sinking 8mA current	VIO=3.3V, sinking 8mA current		0.3	0.4	V
VOL		VIO=1.8V, sinking 3mA current	VIO=1.8V, sinking 3mA current		0.3	0.4	V

VOH	High-Level	VIO=5V, output 10mA	Current VIO-0.5	VIO-0.4		V
VOH	Output Voltage	VIO=3.3V, output 5mA current	VIO-0.4	VIO-0.3		V
VOH	Non-Reset State	VIO=1.8V, output 2mA current	VIO-0.4	VIO-0.3		V
IPUP	Serial Port and RST Pin VIO=5V	Serial Port and RST Pin VIO=5V	35	150	220	μA
	Pull-up Current VIO=3.3V	Pull-up Current VIO=3.3V	15	60	90	μA
	(Pulled up to VIO voltage) VIO=1.8V	(Pulled up to VIO voltage) VIO=1.8V	3	14	21	μA
IPDN	VBUS>1.6V	VBUS>1.6V	6	10	16	μA
	VBUS Pin Pull-down Current VBUS<1.3V	VBUS Pin Pull-down Current VBUS<1.3V	50	140	200	μA
VRV3	V3 Power-on Reset / Low-Voltage Reset Voltage Threshold	V3 Power-on Reset / Low-Voltage Reset Voltage Threshold	2.5	2.7	2.9	V
VRVIO	VIO Power Low-Voltage Reset Voltage Threshold	VIO Power Low-Voltage Reset Voltage Threshold	0.8	1.0	1.15	V
VESD	HBM ESD Withstand Voltage on USB or I/O Pins	HBM ESD Withstand Voltage on USB or I/O Pins	5	6		KV

Order Part Number	Package Type	Package Description	Temperature Range
CH343P	QFN16_3X3	Square Leadless 16-pin	-40°C to 85°C
CH343G	SOP16	Standard 16-pin SMT	-40°C to 85°C
CH343C	SOP16	Standard 16-pin SMT	-40°C to 85°C
CH343K	ESSOP10	Narrow Pitch 10-pin SMT with exposed pad	-40°C to 85°C