CP2108-B03-GMR from SKYWORKS SILICON LABS, in a QFN-64-EP(9x9). Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	RX3	input	UART 3 Receive (RX), high-drive input (VIOHD domain, 2.7-6.0 V).
2	VSSHD	power_in	High-drive device ground for UART 3 pins 1-6. Connect to device ground.
3	VIOHD	power_in	High-drive I/O supply voltage input for UART 3 pins 1-6, 2.7 V to 6.0 V.
4	TX3	output	UART 3 Transmit (TX), high-drive output (VIOHD domain).
5	CTS3	input	UART 3 Clear to Send (CTS), high-drive input.
6	RTS3	output	UART 3 Ready to Send (RTS), high-drive output.
7	RI3	input	UART 3 Ring Indicator (RI). Indicates modem detected a ringing signal.
8	DCD3	input	UART 3 Data Carrier Detect (DCD).
9	DSR3	input	UART 3 Data Set Ready (DSR).
10	DTR3	output	UART 3 Data Terminal Ready (DTR).
11	RI2	input	UART 2 Ring Indicator (RI).
12	DCD2	input	UART 2 Data Carrier Detect (DCD).
13	CTS2	input	UART 2 Clear to Send (CTS).
14	RTS2	output	UART 2 Ready to Send (RTS).
15	RX2	input	UART 2 Receive (RX).
16	TX2	output	UART 2 Transmit (TX).
17	DSR2	input	UART 2 Data Set Ready (DSR).
18	DTR2	output	UART 2 Data Terminal Ready (DTR).
19	/SUSPEND	output	Suspend indicator, active low. Asserted when USB is in suspend state.
20	SUSPEND	output	Suspend indicator, active high. Asserted when USB is in suspend state.
21	GPIO.15	bidirectional	General Purpose I/O 15. Alternate function: Clock Output 3.
22	GPIO.14	bidirectional	General Purpose I/O 14. Alternate function: UART 3 RS-485 transceiver control.
23	GPIO.13	bidirectional	General Purpose I/O 13. Alternate function: UART 3 RX toggle indicator.
24	VIO	power_in	Non-high-drive I/O supply voltage input, 3.0 V to VDD.
25	VSS	power_in	Device ground.
26	GPIO.12	bidirectional	General Purpose I/O 12. Alternate function: UART 3 TX toggle indicator.
27	GPIO.11	bidirectional	General Purpose I/O 11. Alternate function: Clock Output 2.
28	GPIO.10	bidirectional	General Purpose I/O 10. Alternate function: UART 2 RS-485 transceiver control.
29	GPIO.9	bidirectional	General Purpose I/O 9. Alternate function: UART 2 RX toggle indicator.
30	GPIO.8	bidirectional	General Purpose I/O 8. Alternate function: UART 2 TX toggle indicator.
31	GPIO.7	bidirectional	General Purpose I/O 7. Alternate function: Clock Output 1.
32	GPIO.6	bidirectional	General Purpose I/O 6. Alternate function: UART 1 RS-485 transceiver control.
33	GPIO.5	bidirectional	General Purpose I/O 5. Alternate function: UART 1 RX toggle indicator.
34	GPIO.4	bidirectional	General Purpose I/O 4. Alternate function: UART 1 TX toggle indicator.
35	NC	unconnected	No Connect. Leave floating or tie to ground.
36	NC	unconnected	No Connect. Leave floating or tie to ground.
37	GPIO.3	bidirectional	General Purpose I/O 3. Alternate function: Clock Output 0.
38	GPIO.2	bidirectional	General Purpose I/O 2. Alternate function: UART 0 RS-485 transceiver control.
39	VIO	power_in	Non-high-drive I/O supply voltage input, 3.0 V to VDD.
40	GPIO.1	bidirectional	General Purpose I/O 1. Alternate function: UART 0 RX toggle indicator.
41	GPIO.0	bidirectional	General Purpose I/O 0. Alternate function: UART 0 TX toggle indicator.
42	RI1	input	UART 1 Ring Indicator (RI).
43	DCD1	input	UART 1 Data Carrier Detect (DCD).
44	DSR1	input	UART 1 Data Set Ready (DSR).
45	DTR1	output	UART 1 Data Terminal Ready (DTR).
46	CTS1	input	UART 1 Clear to Send (CTS).
47	RTS1	output	UART 1 Ready to Send (RTS).
48	RX1	input	UART 1 Receive (RX).
49	TX1	output	UART 1 Transmit (TX).
50	RI0	input	UART 0 Ring Indicator (RI).
51	DCD0	input	UART 0 Data Carrier Detect (DCD).
52	DSR0	input	UART 0 Data Set Ready (DSR).
53	DTR0	output	UART 0 Data Terminal Ready (DTR).
54	CTS0	input	UART 0 Clear to Send (CTS).
55	RTS0	output	UART 0 Ready to Send (RTS).
56	RX0	input	UART 0 Receive (RX).
57	TX0	output	UART 0 Transmit (TX).
58	VDD	power_in	Core power supply voltage input (also serves as voltage regulator output). 3.0-3.6 V self-powered.
59	VSS	power_in	Device ground.
60	VREGIN	power_in	Voltage regulator input, 4.0-5.5 V when USB bus-powered. Feeds the on-chip 3.3 V voltage regulator.
61	VBUS	input	USB VBUS sense input. Connect to VBUS signal of USB network.
62	D+	bidirectional	USB D+ data line, full-speed (12 Mbps) transceiver.
63	D-	bidirectional	USB D- data line, full-speed (12 Mbps) transceiver.
64	RESET	bidirectional	Active-low device reset. Open-drain output of internal POR/VDD monitor; can be driven low externally to force a system reset.

Key specifications

Parameter	Value
Manufacturer	SKYWORKS SILICON LABS
Package	QFN-64-EP(9x9)
Category	Interface
Pins	64

Ordering variants

Same part, different packaging or reel option.

CP2108-B03-GMR

CAD (KiCad official)

Symbol: CP2108-B03-GMR
Footprint: Package_DFN_QFN:QFN-64-1EP_9x9mm_P0.5mm_EP6x6mm
3D model: QFN-64-EP(9x9) (KiCad packages3D, STEP)

Provenance

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

Datasheet: SKYWORKS SILICON LABS datasheet (35 pp, sha256 b08863a6cad1259c, retrieved 2026-08-17, tier: lcsc)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF