XD74LS181

@@ -0,0 +1,59 @@+# XD74LS181++**XINLUDA** · Specialty Logic · DIP-24++XD74LS181 from XINLUDA, in a DIP-24. 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 | B0 | input | B-operand bit 0 input (active-low B0 for Table 1 / active-high B0 for Table 2). One of the four bits of the B operand presented to the ALU. |+| 2 | A0 | input | A-operand bit 0 input (active-low A0 for Table 1 / active-high A0 for Table 2). One of the four bits of the A operand presented to the ALU. |+| 3 | S3 | input | Function-select input bit 3. Together with S0-S2 selects one of 16 arithmetic or logic operations per Tables 1 and 2. |+| 4 | S2 | input | Function-select input bit 2. Together with S0, S1, S3 selects one of 16 ALU operations. |+| 5 | S1 | input | Function-select input bit 1. Together with S0, S2, S3 selects one of 16 ALU operations. |+| 6 | S0 | input | Function-select input bit 0. Together with S1, S2, S3 selects one of 16 ALU operations. |+| 7 | Cn | input | Carry input to the ALU (active-low Cn for Table 1 / active-high Cn for Table 2). Provides the incoming carry for arithmetic operations; ignored during logic operations when M is high. |+| 8 | M | input | Mode control input. M=H selects the 16 logic functions (internal carry disabled); M=L selects the 16 arithmetic operations (internal carries enabled). |+| 9 | F0 | output | Function output bit 0 (active-low F0 for Table 1 / active-high F0 for Table 2). Represents bit 0 of the ALU result F. |+| 10 | F1 | output | Function output bit 1 (active-low F1 for Table 1 / active-high F1 for Table 2). Represents bit 1 of the ALU result F. |+| 11 | F2 | output | Function output bit 2 (active-low F2 for Table 1 / active-high F2 for Table 2). Represents bit 2 of the ALU result F. |+| 12 | GND | power_in | Ground reference (0 V) for the device. |+| 13 | F3 | output | Function output bit 3 (active-low F3 for Table 1 / active-high F3 for Table 2). Represents the most-significant bit of the ALU result F. |+| 14 | A=B | output | Comparator output. Open-collector; goes high when the four F outputs are all high, indicating A equals B when the ALU is in subtract mode with Cn=H. Can be wire-AND'd across cascaded devices for comparison of more than four bits. |+| 15 | P | output | Carry propagate output (active-low P for Table 1 / X for Table 2). Used with a look-ahead carry generator such as the SN74LS182 to build fast wider adders. |+| 16 | Cn+4 | output | Ripple carry output from the ALU (active-low Cn+4 for Table 1 / active-high Cn+4 for Table 2). Provides the carry to the next 4-bit slice when full look-ahead is not used. |+| 17 | G | output | Carry generate output (active-low G for Table 1 / Y for Table 2). Combined with P and a look-ahead carry generator to produce fast carries for wider adders. |+| 18 | B3 | input | B-operand bit 3 (MSB) input (active-low B3 for Table 1 / active-high B3 for Table 2). |+| 19 | A3 | input | A-operand bit 3 (MSB) input (active-low A3 for Table 1 / active-high A3 for Table 2). |+| 20 | B2 | input | B-operand bit 2 input (active-low B2 for Table 1 / active-high B2 for Table 2). |+| 21 | A2 | input | A-operand bit 2 input (active-low A2 for Table 1 / active-high A2 for Table 2). |+| 22 | B1 | input | B-operand bit 1 input (active-low B1 for Table 1 / active-high B1 for Table 2). |+| 23 | A1 | input | A-operand bit 1 input (active-low A1 for Table 1 / active-high A1 for Table 2). |+| 24 | VCC | power_in | Supply voltage input. Recommended 4.75 V to 5.25 V (nominal 5 V); absolute maximum 7 V. |++## Key specifications++| Parameter | Value |+|---|---|+| Manufacturer | XINLUDA |+| Package | DIP-24 |+| Category | Logic |+| Pins | 24 |++## CAD (KiCad official)++- Symbol: `XD74LS181`+- Footprint: `Package_DIP:DIP-24_W7.62mm`+- 3D model: DIP-24 (KiCad packages3D, STEP)++## Provenance++Data extracted from the manufacturer datasheet, not a distributor listing:++- **Datasheet:** [XINLUDA datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8588896624320131072) (11 pp, sha256 `ab5b774bf827e79e`, 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/xd74ls181-datasheet.pdf)

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