# XD74LS21

**XINLUDA** · Gates · DIP-14

XD74LS21 from XINLUDA, in a DIP-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 | 1A | input | Gate 1 input A; input high level min 2 V, low level max 0.8 V, absolute max input voltage 7 V. |
| 2 | 1B | input | Gate 1 input B; input high level min 2 V, low level max 0.8 V, absolute max input voltage 7 V. |
| 3 | NC | unconnected | No internal connection. |
| 4 | 1C | input | Gate 1 input C; input high level min 2 V, low level max 0.8 V, absolute max input voltage 7 V. |
| 5 | 1D | input | Gate 1 input D; input high level min 2 V, low level max 0.8 V, absolute max input voltage 7 V. |
| 6 | 1Y | output | Gate 1 NAND output (Y = NOT(A·B·C·D)); IOH max −0.4 mA, IOL max 8 mA. |
| 7 | GND | power_in | Ground, reference for all voltages. |
| 8 | 2Y | output | Gate 2 NAND output (Y = NOT(A·B·C·D)); IOH max −0.4 mA, IOL max 8 mA. |
| 9 | 2A | input | Gate 2 input A; input high level min 2 V, low level max 0.8 V, absolute max input voltage 7 V. |
| 10 | 2B | input | Gate 2 input B; input high level min 2 V, low level max 0.8 V, absolute max input voltage 7 V. |
| 11 | NC | unconnected | No internal connection. |
| 12 | 2C | input | Gate 2 input C; input high level min 2 V, low level max 0.8 V, absolute max input voltage 7 V. |
| 13 | 2D | input | Gate 2 input D; input high level min 2 V, low level max 0.8 V, absolute max input voltage 7 V. |
| 14 | VCC | power_in | Supply voltage, recommended 4.75 V to 5.25 V (5 V nominal), absolute max 7 V. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | XINLUDA |
| Package | DIP-14 |
| Category | Logic ICs |
| Pins | 14 |

## Electrical characteristics

Limits as printed in the datasheet (page.json `metadata.characteristics` carries them as data).

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Supply voltage | VCC | 4.75 | 5 | 5.25 | V |  | 4 |
| High-level input voltage | VIH | 2 |  |  | V |  | 4 |
| Low-level input voltage | VIL |  |  | 0.8 | V |  | 4 |
| High-level output current | IOH |  |  | -0.4 | mA |  | 4 |
| Low-level output current | IOL |  |  | 8 | mA |  | 4 |
| Operating free-air temperature | TA | 0 |  | 70 | C |  | 4 |
| Supply voltage | VCC |  |  | 7 | V | see Note 1 | 3 |
| Input voltage | VI |  |  | 7 | V | 74LS21 | 3 |
| Storage temperature range | Tstg | -65 |  | 150 | C |  | 3 |
| Input clamp voltage | VIK |  |  | -1.5 | V | VCC = MIN, II = -18 mA | 4 |
| High-level output voltage | VOH | 2.7 | 3.4 |  | V | VCC = MIN, VIL = MAX, IOH = -0.4 mA | 4 |
| Low-level output voltage | VOL |  | 0.25 | 0.4 | V | VCC = MIN, VIH = 2 V, IOL = 4 mA | 4 |
| Low-level output voltage | VOL |  | 0.35 | 0.5 | V | VCC = MIN, VIH = 2 V, IOL = 8 mA | 4 |
| Input current at max input voltage | II |  |  | 0.1 | mA | VCC = MAX, VI = 7 V | 4 |
| High-level input current | IIH |  |  | 20 | A | VCC = MAX, VI = 2.7 V | 4 |
| Low-level input current | IIL |  |  | -0.4 | mA | VCC = MAX, VI = 0.4 V | 4 |
| Short-circuit output current | IOS | -20 |  | -100 | mA | VCC = MAX | 4 |
| Supply current, outputs high | ICCH |  | 1.2 | 2.4 | mA | VCC = MAX, VI = 4.5 V | 4 |
| Supply current, outputs low | ICCL |  | 2.2 | 4.4 | mA | VCC = MAX, VI = 0 V | 4 |
| Propagation delay, low-to-high | tPLH |  | 8 | 15 | ns | VCC = 5 V, TA = 25 C, RL = 2 kΩ, CL = 15 pF | 4 |
| Propagation delay, high-to-low | tPHL |  | 10 | 20 | ns | VCC = 5 V, TA = 25 C, RL = 2 kΩ, CL = 15 pF | 4 |

## CAD (KiCad official)

- Symbol: `XD74LS21`
- Footprint: `Package_DIP:DIP-14_W7.62mm`
- 3D model: DIP-14 (KiCad packages3D, STEP)
- 3D model files: `xd74ls21-etched.step` / `xd74ls21-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `xd74ls21.step` / `xd74ls21.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [XINLUDA datasheet](docs/xd74ls21-datasheet.pdf) (5 pp, sha256 `cf7e6a3bd695af18`, retrieved 2026-10-23, tier: lcsc)
- **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/xd74ls21-datasheet.pdf)