CH452A

@@ -0,0 +1,70 @@+# CH452A++**WCH Jiangsu Qin Heng** · Digital Tube Drivers · SOIC-28-300mil++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](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8618866980522766336) (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](docs/ch452a-datasheet.pdf)

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