# CD74AC161M

**Texas Instruments** · Counters, Dividers · SOIC-16

CD74AC161M from Texas Instruments, in a SOIC-16. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | CLR | input | Asynchronous clear input, active low; sets all Q outputs to low regardless of CLK, LOAD, or enable inputs. |
| 2 | CLK | input | Synchronous clock input, rising edge triggered. |
| 3 | A | input | Data input A for parallel preset operation; loaded to QA when LOAD is low. |
| 4 | B | input | Data input B for parallel preset operation; loaded to QB when LOAD is low. |
| 5 | C | input | Data input C for parallel preset operation; loaded to QC when LOAD is low. |
| 6 | D | input | Data input D for parallel preset operation; loaded to QD when LOAD is low. |
| 7 | ENP | input | Count enable input; ENP and ENT must both be high for counting; does not affect RCO output. |
| 8 | GND | power_in | Ground connection for power return and logic reference. |
| 9 | LOAD | input | Parallel load input, active low; disables counting and loads data A-D to Q outputs on next clock edge. |
| 10 | ENT | input | Count enable input; ENP and ENT must both be high for counting; feed-forward enables RCO at maximum count. |
| 11 | QD | output | Counter output D (most significant bit) for 4-bit binary count. |
| 12 | QC | output | Counter output C for 4-bit binary count. |
| 13 | QB | output | Counter output B for 4-bit binary count. |
| 14 | QA | output | Counter output A (least significant bit) for 4-bit binary count. |
| 15 | RCO | output | Ripple carry output; high pulse when counter reaches maximum (9 or 15) and ENT is high. |
| 16 | VCC | power_in | Power supply input voltage; operating range 1.5V to 5.5V. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | SOIC-16 |
| Category | Logic |
| Pins | 16 |

## CAD (KiCad official)

- Symbol: `CD74AC161M`
- Footprint: `Package_SO:SOIC-16_3.9x9.9mm_P1.27mm`
- 3D model: SOIC-16 (KiCad packages3D, STEP)
- 3D model files: `cd74ac161m-etched.step` / `cd74ac161m-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `cd74ac161m.step` / `cd74ac161m.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Texas Instruments datasheet](https://www.ti.com/cn/lit/gpn/cd74ac161) (23 pp, sha256 `cc0df0be38defb4e`, retrieved 2026-09-27, tier: lcsc)
- **Datasheet language:** Chinese. Pin names, descriptions, and specs on this page were extracted and translated to English by ds2sf; the linked PDF is the manufacturer original.
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.2`, primary `claude-haiku-4-5-20251001` (text), consensus `claude-sonnet-4-6` (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/cd74ac161m-datasheet.pdf)