SN75ALS191

series introduction

# SN75ALS191 Product Series Introduction

## 1. Overview
The SN75ALS191 is a highly regarded product series within the realm of digital integrated circuits. It belongs to the family of synchronous up/down binary counters, which are fundamental building blocks in various digital systems. These counters are designed to perform accurate and reliable counting operations, making them suitable for a wide range of applications in electronics, telecommunications, and industrial control.

## 2. Key Features

### 2.1 Synchronous Operation
One of the standout features of the SN75ALS191 series is its synchronous operation. In a synchronous counter, all flip - flops are triggered by the same clock signal. This ensures that the counting process is well - coordinated and free from the propagation delays associated with asynchronous counters. As a result, the SN75ALS191 can operate at higher frequencies, providing faster and more stable counting performance.

### 2.2 Up/Down Counting Capability
The SN75ALS191 offers the flexibility of both up - counting and down - counting. A dedicated control input allows the user to easily select between these two counting modes. This feature is extremely useful in applications where bidirectional counting is required, such as in position control systems or frequency division circuits.

### 2.3 Parallel Load Function
The series is equipped with a parallel load input. This enables the user to preset the counter to a specific value instantaneously. By applying the desired data to the parallel data inputs and activating the parallel load control signal, the counter can be loaded with the new value on the next clock edge. This functionality is valuable in applications where the counter needs to start from a non - zero initial value or be re - initialized during operation.

### 2.4 Ripple Clock Output
The SN75ALS191 provides a ripple clock output. This output can be used to cascade multiple counters together to create larger - scale counting systems. By connecting the ripple clock output of one counter to the clock input of another, it is possible to build multi - stage counters with a higher counting range.

### 2.5 High - Speed Operation
Designed with advanced semiconductor technology, the SN75ALS191 is capable of high - speed operation. It can handle clock frequencies in the megahertz range, making it suitable for applications that require fast counting and processing, such as high - speed data acquisition systems and digital communication interfaces.

### 2.6 Low Power Consumption
In addition to its high - speed performance, the SN75ALS191 series is also known for its relatively low power consumption. This makes it an energy - efficient choice for battery - powered devices or applications where power management is a critical concern.

## 3. Pin Configuration and Functionality

### 3.1 Pinout
The SN75ALS191 typically comes in a standard 16 - pin package. The pins are carefully assigned to perform specific functions related to the counter's operation.
- **Clock Input (CLK)**: This pin receives the clock signal that drives the counting process. The counter advances its state on the rising or falling edge of the clock signal, depending on the internal design.
- **Up/Down Control Input (U/D)**: A logic high on this pin selects the up - counting mode, while a logic low selects the down - counting mode.
- **Parallel Load Input (PL)**: When this pin is activated (usually by a low logic level), the counter loads the data present on the parallel data inputs (D0 - D3) on the next clock edge.
- **Parallel Data Inputs (D0 - D3)**: These four pins are used to provide the data that will be loaded into the counter when the parallel load function is enabled.
- **Ripple Clock Output

Images for reference

8-SOIC

8-DIP

8-SOIC

Datasheets

• SN75ALS191
• SN75ALS191
• PDF 3

Partlist