CH452A from WCH Jiangsu Qin Heng, in a SOIC-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	DIG7	output	Word drive output 7 for LED nixie tube (active low, ~4x25 mA sink). Also used as column-scan output during keyboard scan. DIG6/DIG7 can be reused as GPO universal outputs.
2	DIG6	output	Word drive output 6 for LED nixie tube (active low). Also used as column-scan output during keyboard scan and can be reused as GPO.
3	DIG5	output	Word drive output 5 for LED nixie tube (active low). Also used as column-scan output during keyboard scan.
4	DIG4	output	Word drive output 4 for LED nixie tube (active low). Also used as column-scan output during keyboard scan.
5	DIG3	output	Word drive output 3 for LED nixie tube (active low). Also used as column-scan output during keyboard scan.
6	DIG2	output	Word drive output 2 for LED nixie tube (active low). Also used as column-scan output during keyboard scan.
7	DIG1	output	Word drive output 1 for LED nixie tube (active low). Also used as column-scan output during keyboard scan.
8	DIG0	output	Word drive output 0 for LED nixie tube (active low). Also used as column-scan output during keyboard scan.
9	GND	power_in	Common ground. Continuous current not less than 150 mA.
10	GND	power_in	Common ground. Continuous current not less than 150 mA.
11	NC/GPI	input	No connection or general-purpose input; state reported in bit 7 of the returned key code.
12	RST	output	Power-on reset output, active high. Can be tied to the host MCU reset input.
13	RST#	output	Power-on reset output, active low. Complementary to RST for MCUs needing active-low reset.
14	H3L2	input	Serial interface mode select with built-in pull-up. High selects the 4-wire serial interface; low selects the 2-wire (I2C-like) serial interface.
15	SEG0	bidirectional	Segment drive 0 (active high, ~20 mA source) for LED nixie tube segment A; also acts as keyboard scan input (active high) with built-in pull-down resistor.
16	SEG1	bidirectional	Segment drive 1 (active high) for segment B; also keyboard scan input with built-in pull-down.
17	SEG2	bidirectional	Segment drive 2 (active high) for segment C; also keyboard scan input with built-in pull-down.
18	SEG3	bidirectional	Segment drive 3 (active high) for segment D; also keyboard scan input with built-in pull-down.
19	SEG4	bidirectional	Segment drive 4 (active high) for segment E; also keyboard scan input with built-in pull-down.
20	SEG5	bidirectional	Segment drive 5 (active high) for segment F; also keyboard scan input with built-in pull-down.
21	SEG6	bidirectional	Segment drive 6 (active high) for segment G; also keyboard scan input with built-in pull-down.
22	SEG7	bidirectional	Segment drive 7 (active high) for the decimal point of the LED nixie tube; also keyboard scan input with built-in pull-down.
23	VCC	power_in	Positive power supply, 3V-5V. Continuous current not less than 150 mA. Requires 0.1 uF ceramic and >=100 uF electrolytic decoupling capacitors close to the pin.
24	DOUT/INT#	output	In 4-wire mode: serial data output DOUT (built-in pull-up, open-drain); also serves as keyboard interrupt output, active low. In 2-wire mode: interrupt output INT# (built-in pull-up, open-drain), keyboard interrupt active low.
25	LOAD/ADDR	input	In 4-wire mode: serial data load strobe LOAD (built-in pull-up). In 2-wire mode: address selection ADDR (built-in pull-up) for parallel-connecting two CH452 chips on the same bus.
26	DIN/SDA	bidirectional	In 4-wire mode: serial data input DIN (built-in pull-up). In 2-wire mode: serial data line SDA (semi-bidirectional, open-drain output plus input, built-in pull-up); I2C-compatible 400 kHz.
27	DCLK/SCL	input	In 4-wire mode: serial data clock DCLK (built-in pull-up, up to 10 MHz shift / spec limit 2 MHz for cascade). In 2-wire mode: serial clock SCL (built-in pull-up, 400 kHz I2C-compatible).
28	RSTI	input	Manual reset input, active high, with built-in pull-down resistor. Drives the internal reset and the RST/RST# outputs.

Key specifications

Parameter	Value
Manufacturer	WCH Jiangsu Qin Heng
Package	SOIC-28-300mil
Category	LED Drivers
Pins	28

Ordering variants

Same part, different packaging or reel option.

CH452A
CH452L

CAD (KiCad official)

Symbol: CH452A
Footprint: Package_SO:SOIC-28W_7.5x17.9mm_P1.27mm
3D model: SOIC-28-300mil (KiCad packages3D, STEP)

Provenance

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

Datasheet: WCH Jiangsu Qin Heng datasheet (30 pp, sha256 9bca8400a8383cac, 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