# SN74LS90DR

**Texas Instruments** · Counters, Dividers · SOIC-14

SN74LS90DR from Texas Instruments, in a SOIC-14. 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 | CKB | input | Clock input B for the divide-by-five section, advancing on the high-to-low transition; connect to QA for full decade count. |
| 2 | R0(1) | input | Gated zero-reset input 1; with R0(2) both high resets the counter to zero. |
| 3 | R0(2) | input | Gated zero-reset input 2; with R0(1) both high resets the counter to zero. |
| 4 | NC | unconnected | No internal connection. |
| 5 | VCC | power_in | Positive supply voltage. |
| 6 | R9(1) | input | Gated set-to-nine input 1; with R9(2) both high sets the outputs to BCD nine. |
| 7 | R9(2) | input | Gated set-to-nine input 2; with R9(1) both high sets the outputs to BCD nine. |
| 8 | QC | output | Counter output C of the divide-by-five section. |
| 9 | QB | output | Counter output B of the divide-by-five section. |
| 10 | GND | power_in | Ground. |
| 11 | QD | output | Counter output D, the most significant bit of the divide-by-five section. |
| 12 | QA | output | Counter output A of the divide-by-two section. |
| 13 | NC | unconnected | No internal connection. |
| 14 | CKA | input | Clock input A for the divide-by-two section, advancing on the high-to-low transition; count pulses are applied here. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | SOIC-14 |
| Category | Logic |
| Pins | 14 |

## CAD (KiCad official)

- Symbol: `SN74LS90DR`
- Footprint: `Package_SO:SOIC-14_3.9x8.7mm_P1.27mm`
- 3D model: SOIC-14 (KiCad packages3D, STEP)
- 3D model files: `sn74ls90dr-etched.step` / `sn74ls90dr-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `sn74ls90dr.step` / `sn74ls90dr.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/lit/ds/symlink/sn74ls90.pdf) (27 pp, sha256 `43d2e13b0f0e6ce2`, retrieved 2026-10-08, tier: manufacturer)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-5-5` (text+vision), consensus `claude-opus-5-5` (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/sn74ls90dr-datasheet.pdf)