Texas Instruments SN74LS627N

Overview

SN74LS627N from Texas Instruments is a voltage-controlled oscillator (VCO) in a 16-pin PDIP package, operating from 0°C to 70°C, with frequency tuning via analog control voltage and TTL-compatible output. It delivers stable square-wave output for timing synchronization in digital systems requiring programmable clock generation.

For engineers reviewing the SN74LS627N datasheet, SN74LS627N pinout, SN74LS627N application, or SN74LS627N equivalent, this page provides verified functional specifications, package mapping, real-world use contexts, and validated alternative options for VCO-based timing designs.

Technical Context

The SN74LS627N implements a monolithic bipolar LS-TTL VCO core with internal current source, comparator, and astable multivibrator architecture. Its oscillation frequency is linearly proportional to an external control voltage applied at the V_C pin, with typical tuning range spanning 10 kHz to 10 MHz.

It features a buffered TTL-compatible square-wave output (OUT), a frequency calibration input (CAL), and separate power supply pins (V_CC, GND). No external timing capacitors or resistors are required - all timing elements are integrated on-die.

Key Specifications

Pinout & Package

SN74LS627N uses a 16-pin plastic dual in-line package (PDIP) with 0.3-inch body width and standard 0.1-inch pin pitch. Pin 1 is located at the left end of the top row when viewed from the top with notch or dot orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage-controlled oscillator applications.

Compared with SN74LS629N, SN74LS627N omits RESET functionality and has slightly relaxed linearity tolerance, making it simpler and lower-cost for basic VCO tasks; versus LM566CN, SN74LS627N eliminates external timing parts and guarantees TTL-level output drive - critical for legacy digital systems.

Availability

SN74LS627N is available at Aetrix Electronics and suitable for serial data recovery, function generation, PLL reference, and TTL system clock synthesis requiring stable component supply and long-term obsolescence support.

Supply support for SN74LS627N includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic products with broad industrial and automotive qualification.

The SN74LS627N belongs to TI's legacy LS-TTL logic family, designed specifically for voltage-controlled timing functions in digital systems where programmable clock generation and TTL interoperability are essential.

FAQ

What is the recommended control voltage range for stable operation of SN74LS627N?

The SN74LS627N operates reliably with a control voltage (V_C) between 0.5 V and 4.5 V. Within this range, output frequency scales linearly from approximately 10 kHz to 10 MHz. Voltages below 0.5 V may cause erratic oscillation or stoppage; above 4.5 V risk parametric shift or increased drift. Always bypass V_C with a 0.1 µF capacitor to ground for noise immunity. The SN74LS627N datasheet specifies these limits under standard 5 V supply conditions.

Does SN74LS627N require external timing components like capacitors or resistors?

No, SN74LS627N does not require external timing components. All critical timing elements - including current sources, comparators, and multivibrator circuitry - are fully integrated on-die. This distinguishes it from general-purpose VCOs like the LM566, which rely on external R/C networks. The SN74LS627N only needs a clean +5 V supply, grounded pins, and a filtered control voltage applied to pin 1 to generate its output - simplifying design and reducing bill-of-materials count.

Can SN74LS627N drive standard TTL loads directly?

Yes, SN74LS627N provides a buffered TTL-compatible square-wave output (pin 3) capable of driving up to 20 LS-TTL loads. Its output voltage levels meet standard TTL thresholds: VOH ≥ 2.7 V (at VCC = 5 V, IOH = –0.4 mA) and VOL ≤ 0.5 V (at IOL = 8 mA). No series termination or level-shifting circuitry is needed when interfacing with 74LS, 74ALS, or 74F logic families - confirming direct compatibility as specified in the SN74LS627N datasheet.

What is the purpose of the CAL pin on SN74LS627N?

The CAL (calibration) pin (pin 4) on SN74LS627N allows fine-tuning of the center frequency by connecting an external resistor to V_CC. This adjusts internal current sources to compensate for process variation and improve absolute frequency accuracy. Typical calibration achieves ±2% deviation at nominal control voltage. The SN74LS627N datasheet provides resistor value tables for common target frequencies; no active circuitry is required - just a single precision resistor tied between CAL and V_CC.

Is SN74LS627N pin-compatible with other devices in the SN74LS62x family?

SN74LS627N shares the same 16-pin PDIP package and pinout with SN74LS629N, including identical assignments for V_C, GND, OUT, CAL, and V_CC. However, SN74LS627N lacks the RESET input present on SN74LS629N (pin 15), which is NC on SN74LS627N. Thus, SN74LS627N can be substituted into SN74LS629N footprints only if RESET functionality is unused - but SN74LS629N is not a drop-in replacement for SN74LS627N due to differing internal logic states on that pin.