74LS90 Decade Counter IC (7490) DIP 14 Package

74LS90 Decade Counter IC (7490) DIP 14 Package

The 74LS90 is a 4-bit decade counter belonging to the 74LS (Low-Power Schottky TTL) logic family.
It can function as:

• A divide-by-2 counter,
• A divide-by-5 counter, or
• Combined as a divide-by-10 (decade counter).

It consists of four JK flip-flops internally arranged to produce a mod-10 counting sequence (0000 ? 1001) and automatically resets to 0000 on the next clock pulse.

The IC is widely used in digital clocks, frequency dividers, timing circuits, and event counters.

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Features:-

• A decade counter is a binary counter that is designed to count to 1010b.
• By changing the modes of Decade Counter IC, the chip can count up to other maximum numbers and return to zero.
• The Decade Counter IC consists of four master-slave JK flip-flops internally connected to provide a MOD-2 (count-to-2) counter and a MOD-5 (count-to-5) counter.
• Decade counter is one that counts in decimal digits, rather than binary. A decade counter may have each or other binary encodings.

Specifications:-

• Type:                         DIP, JK Flip-Flop
• Voltage Rating:           4.75 to 5.25V
• Current Rating:           8mA Low Level and – 0.4mA High Level Output Current
• Temperature Rating:    0 to 70 Deg C
• Number of Bits:           4 bit

Functional Description

• Asynchronous Reset (Pins 2 & 3):
  When both reset inputs are HIGH, all flip-flops reset to 0000 (Q outputs LOW).
• Asynchronous Preset (R9(1), R9(2)):
  Sets the counter to binary 1001 (decimal 9).
• Clock Inputs:
• CLK_A drives the ÷2 section (QA).
• CLK_B drives the ÷5 section (QB, QC, QD).
  When properly connected, they form a decade counter

Applications

• Digital clocks / timers
• Frequency dividers
• Event and pulse counters
• Digital display counters
• Sequencing and timing logic
• Binary coded decimal (BCD) counters

74ls90-ic-datasheet