CH376S from WCH Jiangsu Qin Heng, in a SOP-28-300mil. 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	INT#	output	Interrupt request output to the MCU, active low, with built-in pull-up resistor. Signals events such as USB connect/disconnect, command completion, or file-system status.
2	RSTI	input	External hardware reset input, active low, with built-in pull-down resistor. Tie high or leave floating for normal operation; pull low to force a hardware reset.
3	WR#	input	Write strobe input of the 8-bit passive parallel port, active low, with built-in pull-up resistor. Latches data on the D0-D7 bus into CH376 when PCS# is asserted.
4	RD#	input	Read strobe input of the 8-bit passive parallel port, active low, with built-in pull-up resistor. Drives the D0-D7 bus with CH376 output data when PCS# is asserted.
5	TXD	bidirectional	Dual-function pin: interface-mode selection input during power-on reset (with internal pull-up), then serial data output of the asynchronous UART after reset.
6	RXD	input	Serial data input of the asynchronous UART, with built-in pull-up resistor. Idle-high; receives serial commands from the MCU at up to 3 Mbps.
7	SD_DI	input	SD-card SPI host MISO input (data from SD card to CH376), with built-in pull-up resistor. Sampled by CH376 on the SD_CK edge.
8	A0	input	Parallel-port address input with built-in pull-up resistor. A0=1 selects the command/status register, A0=0 selects the data register.
9	V3	power_in	3.3 V core rail. Tie directly to VCC when powered from 3.3 V; add an external 0.01 uF decoupling capacitor when VCC is 5 V (built-in LDO supplies the core).
10	UD+	bidirectional	USB bus D+ data line. Connects directly to the USB connector D+ pin; no external series resistor is required.
11	UD-	bidirectional	USB bus D- data line. Connects directly to the USB connector D- pin; no external series resistor is required.
12	GND	power_in	Common ground reference. Must be tied to the USB bus ground and to the local system ground.
13	XI	input	Crystal oscillator input. Connect an external 12 MHz crystal between XI and XO with the standard load capacitors to ground.
14	XO	output	Inverted crystal oscillator output. Connect an external 12 MHz crystal between XI and XO with the standard load capacitors to ground.
15	D0	bidirectional	Bit 0 of the 8-bit bidirectional parallel data bus, three-state, with built-in pull-up resistor. Driven by CH376 during reads and by the MCU during writes.
16	D1	bidirectional	Bit 1 of the 8-bit bidirectional parallel data bus, three-state, with built-in pull-up resistor.
17	D2	bidirectional	Bit 2 of the 8-bit bidirectional parallel data bus, three-state, with built-in pull-up resistor.
18	SCS/D3	bidirectional	Muxed pin. In SPI slave mode: SPI chip-select input, active low, with built-in pull-up resistor. In parallel mode: bit 3 of the D0-D7 bus.
19	BZ/D4	bidirectional	Muxed pin. In SPI slave mode: BZ busy-status output, active high, indicating CH376 is processing. In parallel mode: bit 4 of the D0-D7 bus.
20	SCK/D5	bidirectional	Muxed pin. In SPI slave mode: SPI serial clock input, with built-in pull-up resistor. In parallel mode: bit 5 of the D0-D7 bus.
21	SDI/D6	bidirectional	Muxed pin. In SPI slave mode: SPI MOSI serial data input, with built-in pull-up resistor. In parallel mode: bit 6 of the D0-D7 bus.
22	SDO/D7	bidirectional	Muxed pin. In SPI slave mode: SPI MISO serial data output, three-state (may also serve as an interrupt output via CMD_SET_SDO_INT). In parallel mode: bit 7 of the D0-D7 bus.
23	SD_CS	output	SD-card SPI host chip-select output, open-drain, active low, with built-in pull-up resistor. Drives the CS pin of the attached SD/MMC/TF card.
24	ACT#	output	Open-drain status output, active low, with built-in pull-up resistor. Indicates USB-device connection in host mode, SD-card SPI transfer success in SD host mode, or completion of USB-device configuration in device mode with built-in firmware. Typically drives an activity LED.
25	SD_DO/RST	output	Muxed pin. Before SD-card mode is entered: RST power-on reset output, active high, usable to reset the external MCU. After SD-card mode is entered: SD_DO SPI-host serial data output (MOSI) to the SD card.
26	SD_CK	output	SD-card SPI host serial clock output. Drives the SCLK pin of the attached SD/MMC/TF card at up to 6 MHz.
27	PCS#	input	Parallel-port chip-select input, active low, with built-in pull-up resistor. Enables the 8-bit passive parallel interface when asserted.
28	VCC	power_in	Positive supply input, nominally 5 V, 3.3 V, or 3 V. Requires an external 0.1 uF decoupling capacitor placed close to the pin.

Key specifications

Parameter	Value
Manufacturer	WCH Jiangsu Qin Heng
Package	SOP-28-300mil
Category	Interface
Pins	28

Ordering variants

Same part, different packaging or reel option.

CH376S
CH376T

CAD (KiCad official)

Symbol: CH376S
Footprint: Package_SO:SOP-28_8.4x18.16mm_P1.27mm
3D model: SOP-28-300mil (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`ch376s.step`	362 KB	You want the bare part, or you mark your own boards.
`ch376s-etched.step`	2.6 MB	You want the part with `CH376S` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 648 faces against 447 in the bare model. It survives export, section views, and rendering in any CAD tool, and it drops straight into KiCad or Fusion with no extra setup.

Provenance

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

Datasheet: WCH Jiangsu Qin Heng datasheet (34 pp, sha256 a5b56270d8a36d93, 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