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Contents

README

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SN74LS161ADR

Texas Instruments · Counters, Dividers · SOIC-16

SN74LS161ADR 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 CLR input Active-low asynchronous clear; a low level resets all four flip-flops regardless of clock, load, or enable inputs.
2 CLK input Clock input; all synchronous operations occur on the rising edge of CLK.
3 A input Parallel data input A; loaded into QA on the rising clock edge when LOAD is low.
4 B input Parallel data input B; loaded into QB on the rising clock edge when LOAD is low.
5 C input Parallel data input C; loaded into QC on the rising clock edge when LOAD is low.
6 D input Parallel data input D; loaded into QD on the rising clock edge when LOAD is low.
7 ENP input Count enable parallel input; counting is enabled only when both ENP and ENT are high.
8 GND power_in Ground supply reference (0 V).
9 LOAD input Active-low synchronous parallel load enable; a low level causes the A-D inputs to be loaded on the next rising clock edge.
10 ENT input Count enable trickle input; enables counting when high (along with ENP) and also enables the RCO output.
11 QD output Flip-flop D (MSB) counter output; represents the 2³ bit of the synchronous binary count.
12 QC output Flip-flop C counter output; represents the 2² bit of the synchronous binary count.
13 QB output Flip-flop B counter output; represents the 2¹ bit of the synchronous binary count.
14 QA output Flip-flop A (LSB) counter output; represents the 2⁰ bit of the synchronous binary count.
15 RCO output Ripple carry output; goes high when the count is at terminal count (15) and ENT is high, enabling cascaded counting.
16 VCC power_in Positive supply voltage; LS-family typical operating range 4.75 V to 5.25 V.

Key specifications

Parameter Value
Manufacturer Texas Instruments
Package SOIC-16
Category Logic
Pins 16

CAD (KiCad official)

  • Symbol: SN74LS161ADR
  • Footprint: Package_SO:SOIC-16_3.9x9.9mm_P1.27mm
  • 3D model: SOIC-16 (KiCad packages3D, STEP)
  • 3D model files: sn74ls161adr-etched.step / sn74ls161adr-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); sn74ls161adr.step / sn74ls161adr.glb are the bare package body.

Provenance

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

  • Datasheet: Texas Instruments datasheet (40 pp, sha256 0ea50a72dfbd95c3, retrieved 2026-09-27, tier: manufacturer)
  • Extractor: parts-factory 2.0.0 / extract_pins 0.2, primary claude-sonnet-4-6 (text+vision), consensus claude-opus-4-7 (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