component
SN74LS221DR
Public Made by Adomby adom
Texas Instruments Monostable Multivibrators, SOIC-16. Pinout reviewed by a person against the datasheet, KiCad symbol/footprint/3D.
3D Model
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Symbol & Footprint
Schematic Symbol
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PCB Footprint
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Datasheet
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README
markdownSN74LS221DR
Texas Instruments · Monostable Multivibrators · SOIC-16
SN74LS221DR 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 | 1Cext | passive | Timing capacitor connection for monostable 1; connect timing capacitor between this pin and GND. |
| 2 | 1Q | output | Q output (true) of monostable 1; TTL-compatible output. |
| 3 | 1Q | output | Q output (inverted) of monostable 1; TTL-compatible output. |
| 4 | NC | unconnected | No internal connection. |
| 5 | 2Q | output | Q output (inverted) of monostable 2; TTL-compatible output. |
| 6 | 2CLR | input | Clear input for monostable 2; overriding clear terminates output pulse; active low with Req = 12.5 kΩ NOM. |
| 7 | 2B | input | B input (Schmitt trigger) of monostable 2; positive-transition triggered; Req = 15.4 kΩ NOM for LS221. |
| 8 | 2A | input | A input of monostable 2; negative-transition triggered; Req = 25 kΩ NOM for LS221. |
| 9 | GND | power_in | Ground; 0 V reference. |
| 10 | 2Rext/Cext | passive | Timing resistor and capacitor connection for monostable 2; never more positive than 2Cext terminal; range 1.4 to 100 kΩ for Rext. |
| 11 | 2Cext | passive | Timing capacitor connection for monostable 2; connect timing capacitor between this pin and GND; range 0 to 1000 µF for Cext. |
| 12 | VCC | power_in | Power supply; +5 V nominal (4.75 to 5.25 V operating range for SN74LS221). |
| 13 | 1CLR | input | Clear input for monostable 1; overriding clear terminates output pulse; active low with Req = 12.5 kΩ NOM. |
| 14 | 1B | input | B input (Schmitt trigger) of monostable 1; positive-transition triggered; Req = 15.4 kΩ NOM for LS221. |
| 15 | 1A | input | A input of monostable 1; negative-transition triggered; Req = 25 kΩ NOM for LS221. |
| 16 | 1Rext/Cext | passive | Timing resistor and capacitor connection for monostable 1; never more positive than 1Cext terminal; range 1.4 to 100 kΩ for Rext. |
Key specifications
| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | SOIC-16 |
| Category | Logic |
| Pins | 16 |
CAD (KiCad official)
- Symbol:
SN74LS221DR - Footprint:
Package_SO:SOIC-16_3.9x9.9mm_P1.27mm - 3D model: SOIC-16 (KiCad packages3D, STEP)
- 3D model files:
sn74ls221dr-etched.step/sn74ls221dr-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);sn74ls221dr.step/sn74ls221dr.glbare the bare package body.
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: Texas Instruments datasheet (31 pp, sha256
6a9b0a69e8f80f2b, retrieved 2026-09-29, tier: manufacturer) - 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).