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SN74LS221DBR
Public Made by Adomby adom
Texas Instruments Monostable Multivibrators, SSOP-16-208mil. Pinout cross-checked by two models against the datasheet, KiCad symbol/footprint/3D.
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README.mdadded+52@@ -0,0 +1,52 @@+# SN74LS221DBR++**Texas Instruments** · Monostable Multivibrators · SSOP-16-208mil++SN74LS221DBR from Texas Instruments, in a SSOP-16-208mil. 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 | Monostable 1 negative-transition-triggered input, which can also be used as an inhibit input; unused inputs must be held at VCC or GND. |+| 2 | 1B | input | Monostable 1 positive-transition-triggered Schmitt-trigger input, which can also be used as an inhibit input. |+| 3 | 1CLR | input | Monostable 1 active-low overriding clear input that terminates the output pulse. |+| 4 | 1Q̄ | output | Monostable 1 complementary (inverted) totem-pole output, high when idle; IOL 8 mA max and IOH -400 µA for the SN74LS221. |+| 5 | 2Q | output | Monostable 2 totem-pole output, low when idle and high during the pulse; IOL 8 mA max and IOH -400 µA for the SN74LS221. |+| 6 | 2Cext | passive | Monostable 2 external timing capacitor connection; the Rext/Cext terminal is never more positive than this terminal. |+| 7 | 2Rext/Cext | passive | Monostable 2 external timing resistor/capacitor junction; Rext 1.4 kΩ min to 100 kΩ max for the SN74LS221, with tw ≈ 0.7·Cext·Rext. |+| 8 | GND | power_in | Ground. |+| 9 | 2A | input | Monostable 2 negative-transition-triggered input, which can also be used as an inhibit input. |+| 10 | 2B | input | Monostable 2 positive-transition-triggered Schmitt-trigger input, which can also be used as an inhibit input. |+| 11 | 2CLR | input | Monostable 2 active-low overriding clear input that terminates the output pulse. |+| 12 | 2Q̄ | output | Monostable 2 complementary (inverted) totem-pole output, high when idle; IOL 8 mA max and IOH -400 µA for the SN74LS221. |+| 13 | 1Q | output | Monostable 1 totem-pole output, low when idle and high during the pulse; IOL 8 mA max and IOH -400 µA for the SN74LS221. |+| 14 | 1Cext | passive | Monostable 1 external timing capacitor connection; the Rext/Cext terminal is never more positive than this terminal. |+| 15 | 1Rext/Cext | passive | Monostable 1 external timing resistor/capacitor junction; Rext 1.4 kΩ min to 100 kΩ max for the SN74LS221, with tw ≈ 0.7·Cext·Rext. |+| 16 | VCC | power_in | Supply voltage, 4.75 V to 5.25 V recommended for the SN74LS221 (7 V absolute maximum). |++## Key specifications++| Parameter | Value |+|---|---|+| Manufacturer | Texas Instruments |+| Package | SSOP-16-208mil |+| Category | Logic ICs |+| Pins | 16 |++## CAD (KiCad official)++- Symbol: `SN74LS221DBR`+- Footprint: `Package_SO:SSOP-16_5.3x6.2mm_P0.65mm`+- 3D model: SSOP-16-208mil (KiCad packages3D, STEP)+- 3D model files: `sn74ls221dbr-etched.step` / `sn74ls221dbr-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `sn74ls221dbr.step` / `sn74ls221dbr.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/sn74ls221) (31 pp, sha256 `9d7f372b30430c70`, retrieved 2026-10-08, 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/sn74ls221dbr-datasheet.pdf)
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unused inputs must be held at VCC or GND."+ },+ {+ "number": "2",+ "name": "1B",+ "type": "input",+ "description": "Monostable 1 positive-transition-triggered Schmitt-trigger input, which can also be used as an inhibit input."+ },+ {+ "number": "3",+ "name": "1CLR",+ "type": "input",+ "description": "Monostable 1 active-low overriding clear input that terminates the output pulse."+ },+ {+ "number": "4",+ "name": "1Q̄",+ "type": "output",+ "description": "Monostable 1 complementary (inverted) totem-pole output, high when idle; IOL 8 mA max and IOH -400 µA for the SN74LS221."+ },+ {+ "number": "5",+ "name": "2Q",+ "type": "output",+ "description": "Monostable 2 totem-pole output, low when idle and high during the pulse; IOL 8 mA max and IOH -400 µA for the SN74LS221."+ },+ {+ "number": "6",+ "name": "2Cext",+ "type": "passive",+ "description": "Monostable 2 external timing capacitor connection; the Rext/Cext terminal is never more positive than this terminal."+ },+ {+ "number": "7",+ "name": "2Rext/Cext",+ "type": "passive",+ "description": "Monostable 2 external timing resistor/capacitor junction; Rext 1.4 kΩ min to 100 kΩ max for the SN74LS221, with tw ≈ 0.7·Cext·Rext."+ },+ {+ "number": "8",+ "name": "GND",+ "type": "power_in",+ "description": "Ground."+ },+ {+ "number": "9",+ "name": "2A",+ "type": "input",+ "description": "Monostable 2 negative-transition-triggered input, which can also be used as an inhibit input."+ },+ {+ "number": "10",+ "name": "2B",+ "type": "input",+ "description": "Monostable 2 positive-transition-triggered Schmitt-trigger input, which can also be used as an inhibit input."+ },+ {+ "number": "11",+ "name": "2CLR",+ "type": "input",+ "description": "Monostable 2 active-low overriding clear input that terminates the output pulse."+ },+ {+ "number": "12",+ "name": "2Q̄",+ "type": "output",+ "description": "Monostable 2 complementary (inverted) totem-pole output, high when idle; IOL 8 mA max and IOH -400 µA for the SN74LS221."+ },+ {+ "number": "13",+ "name": "1Q",+ "type": "output",+ "description": "Monostable 1 totem-pole output, low when idle and high during the pulse; IOL 8 mA max and IOH -400 µA for the SN74LS221."+ },+ {+ "number": "14",+ "name": "1Cext",+ "type": "passive",+ "description": "Monostable 1 external timing capacitor connection; the Rext/Cext terminal is never more positive than this terminal."+ },+ {+ "number": "15",+ "name": "1Rext/Cext",+ "type": "passive",+ "description": "Monostable 1 external timing resistor/capacitor junction; Rext 1.4 kΩ min to 100 kΩ max for the SN74LS221, with tw ≈ 0.7·Cext·Rext."+ },+ {+ "number": "16",+ "name": "VCC",+ "type": "power_in",+ "description": "Supply voltage, 4.75 V to 5.25 V recommended for the SN74LS221 (7 V absolute maximum)."+ }+ ],+ "provenance": {+ "extractor": "extract_pins 0.3",+ "factory_chain": {+ "factory": "2.0.0",+ "extractor": "extract_pins 0.3",+ "primary_model": "claude-sonnet-5-5",+ "primary_mode": "text+vision",+ "consensus_model": "claude-opus-5-5",+ "consensus": "agreed",+ "guards": "pin_guards 0.1: passed",+ "guard_notes": [+ "extractor flagged: Pin types for the Cext and Rext/Cext timing pins are classed as passive because they connect to exte",+ "vision extraction: provenance cannot be text-verified; needs consensus"+ ],+ "pages_sent": 31,+ "cost_usd": 0.3507,+ "at": "2026-10-08T15:48:27"+ },+ "datasheet": {+ "url": "https://www.ti.com/cn/lit/gpn/sn74ls221",+ "pages": 31,+ "sha256": "9d7f372b30430c70",+ "source_tier": "lcsc"+ },+ "cad": "KiCad official (CC-BY-SA 4.0)",+ "pins": {+ "total": 16,+ "described": 16,+ "cites_pages": true,+ "refuses_to_fabricate": true+ }+ },+ "viewers": {+ "symbol": "viewers/symbol.html",+ "footprint": "viewers/footprint.html"+ },+ "models_3d": [+ {+ "file": "sn74ls221dbr.step",+ "role": "plain",+ "up": "Z",+ "units": "mm",+ "origin": "footprint origin = pad-pattern centre",+ "seat": "z = 0",+ "extents_mm": [+ 7.8,+ 6.2,+ 2.1+ ],+ "zmin_mm": 0,+ "centre_offset_mm": 0,+ "footprint_binding": "identity",+ "sha256": "d0e11e46aeca5dbaa5c4bb538f3f4899761267cabdeba6486325ae9e979c03ef",+ "checked": "2026-10-08",+ "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"+ },+ {+ "file": "sn74ls221dbr-etched.step",+ "role": "eda",+ "up": "Z",+ "units": "mm",+ "origin": "footprint origin = pad-pattern centre",+ "seat": "z = 0",+ "extents_mm": [+ 7.8,+ 6.2,+ 2.1+ ],+ "zmin_mm": 0,+ "centre_offset_mm": 0,+ "footprint_binding": "identity",+ "sha256": "0a2393f9541b6adf629d34d80ce570cff51c7b32a1b61ec72760e34037617008",+ "checked": "2026-10-08",+ "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"+ }+ ]+ },+ "visibility": "public",+ "org": "adom",+ "author": {+ "name": "Ray",+ "email": "[email protected]"+ }+}