74LS688 8-bit Magnitude Comparator

The 74LS series of integrated circuits (ICs) was one of the most popular logic families of transistor-transistor logic (TTL) logic chips. 74LS series is a bipolar, low-power Schottky IC.74LS688 is an 8-bit magnitude comparator. 74LS688 is designed to perform comparisons between two eight-bit binary or BCD words. All device types provide P = Q outputs and the LS682 and LS684 have P>Q outputs also.

74LS688 Features

• Designed to Perform Comparisons Between Two 8-bit Binary or BCD Words
• Totem Pole Output
• Provides Equal Comparison Result
• Operating Temperature up to 70°C
• Standard TTL Switching Voltages

74LS688 Specifications

Supply Voltage	4.75 – 5.25Vdc
Maximum Clock Frequency	40Mhz
Power Dissipation	2mW/gate @100kHz
Minimum Output Current	8mA
Propagation Delay	10nS
Fan Out (TTL Loads)	20

74LS688 Pinout Diagram

74LS688 Pin Description

Pin No	Pin Name	Description
1	G’	Enable Input(Active Low)
2	P0	Bit 0 of Comparator 1
3	Q0	Bit 0 of Comparator 2
4	P1	Bit 1 of Comparator 1
5	Q1	Bit 1 of Comparator 2
6	P2	Bit 2 of Comparator 1
7	Q2	Bit 2 of Comparator 2
8	P3	Bit 3 of Comparator 1
9	Q3	Bit 3 of Comparator 2
10	GND	Ground
11	P4	Bit 4 of Comparator 1
12	Q4	Bit 4 of Comparator 2
13	P5	Bit 5 of Comparator 1
14	Q5	Bit 5 of Comparator 2
15	P6	Bit 6 of Comparator 1
16	Q6	Bit 6 of Comparator 2
17	P7	Bit 7 of Comparator 1
18	Q7	Bit 7 of Comparator 2
19	P’=Q’	Comparator Equal Output Pin
20	VCC	Positive Supply

74LS688 Circuit

Below is a circuit of 1-bit magnitude comparator using logic gates (NOT, AND, and NOR).

Applications

• Null detectors
• Zero-crossing detectors
• Relaxation oscillator
• Level shifter
• Analog-to-digital converters
• Window detectors

74LS688 Alternative Equivalent

74LS682

Download 74LS688 8-bit Magnitude Comparator Datasheet from the link given below.