74LS190 Up/Down Decade Counter


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. The 74LS190 is a synchronous UP/DOWN BCD Decade (8421) Counter and State changes of the counters are synchronous with the A LOW-to-HIGH transition of the Clock Pulse input.

74LS190 Features

  • Synchronous Up/Down BCD Decade Counter, Count is Updated with Low-to-High Clock Transition
  • Synchronous Counting
  • High Speed up to 25MHz
  • Individual Preset Inputs
  • Standard TTL Switching Voltages

74LS190 Specifications

Supply Voltage4.75 – 5.25Vdc
Maximum Clock Frequency40Mhz
Power Dissipation2mW/gate @100kHz
Minimum Output Current8mA
Propagation Delay10nS
Fan Out (TTL Loads)20

74LS190 Pinout Diagram

74LS190 Pin Description

Pin NoPin NameDescription
1P1Parallel Data Input
2Q1Flip-Flop Output
3Q0Flip-Flop Output
4CE’Count Enable (Active LOW) Input
5U/DUp/Down Count Control Input
6Q2Flip-Flop Output
7Q3Flip-Flop Output
9P3Parallel Data Input
10P2Parallel Data Input
11PL’Parallel Load Control (Active LOW) Input
12TCTerminal Count Output
13RC’Ripple Clock Output
14CPClock Pulse (Active HIGH going edge) Input
15P0Parallel Data Input
16VCCPositive Supply


  • Clock generation
  • Clock division
  • Integrated oscillator
  • Low power CMOS
  • TTL compatible inputs
  • In frequency counting circuits

74LS190 Alternative Equivalent


Download 74LS190 Up/Down Decade Counter Datasheet from the link given below.