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7400 Series Guide: 74HC112/74LS112 (Dual J-K flip-flop)

The 74×112 (ex 74HC112) is a chip that contains two negative-edge-triggered J-K flip-flops, each with preset and clear capabilities.

In this guide, you’ll learn the things you need to know about this chip in order to use J-K flip-flops effectively in your own projects.

74HC112 / 74LS112 Package And Pinout

What does the 74HC112 / 74LS112 do?

The 74×112 consists of two JK flip-flops. Each flip-flop can store a single bit of data. You can control the state of each flip-flop using its J and K inputs, along with a clock input.

JK flip flop symbol

The flip-flops can be toggled between states based on the input values:

  • When both J and K are LOW, the flip-flop retains its current state.
  • When J is HIGH and K is LOW, the flip-flop sets.
  • When J is LOW and K is HIGH, the flip-flop resets.
  • When both J and K are HIGH, the flip-flop toggles its state.

Additionally, the 74×112 has a clear input that, when activated, will reset the flip-flop to a LOW output state.

J-K Flip-flops are useful for example to build counters and memory devices in digital circuits.

How To Use This Chip

The 74HC112 comes in a 16-pin package, and you need to connect it to power before you can use it. Most 7400 ICs support a VCC voltage of 5V. One difference between the HC and LS version of the chip is that the 74HC112 supports 2V to 6V, while the 74LS112 only supports 5V.

74HC chips can normally supply a maximum of 4 mA from an output pin. If you’re using the 74LS version, the maximum current you can pull out of one output pin is 0.4 mA when the pin is high (sourcing) or 8 mA when the pin is low (sinking).

But these values can differ between models, so check the datasheet of your model to verify.

Once you’ve connected it to power, you can use the Dual J-K flip-flops inside.

7400 series IC connected to 5V on a breadboard
The 74HC112/74LS112 IC connected to power

74×112 Pinout

The 74×112 has 16 pins and contains two negative-edge-triggered J-K flip-flops with set and reset laid out as shown in the pinout diagram below:

74HC112 Pinout
Pin NamePin #TypeDescription
1CLK1InputClock input for the first J-K flip-flop (active low).
1K2InputK input for the first J-K flip-flop.
1J3InputJ input for the first J-K flip-flop.
1SET4InputSet input for the first J-K flip-flop (active low).
1Q5OutputOutput from the first J-K flip-flop.
1Q6OutputInverted output from the first J-K flip-flop.
2Q7OutputInverted output from the second J-K flip-flop.
GND8PowerConnect to ground (GND).
2Q9OutputOutput from the second J-K flip-flop.
2SET10InputSet input for the second J-K flip-flop (active low).
2J11InputJ input for the second J-K flip-flop.
2K12InputK input for the second J-K flip-flop.
2CLK13InputClock input for the second J-K flip-flop (active low).
2RST14InputReset input for the second J-K flip-flop (active low).
1RST15InputReset input for the first J-K flip-flop (active low).
VCC16PowerPositive power supply. Connect to +5V power.
Pin overview for the 74×112 IC

Alternatives and Equivalents for 74HC112 / 74LS112

There are many versions of the 74×112 chip. They all have the same functionality, but with different specifications such as supported voltages and maximum current output.

Here’s a list of a few equivalents of this chip:

  • 74HC112 (High-speed CMOS)
  • 74HCT112 (High-speed CMOS, TTL compatible)
  • 74LS112 (High-speed TTL)
  • 74LVC112 (Low Voltage TTL)
  • 74AC112 (Advanced CMOS)
  • 74ALS112 (Advanced Low-Power Schottky TTL)
  • 74F112 (Very High Speed)
  • 74C112 (CMOS, similar to the 4000-series)

Some manufacturers also add a prefix, such as the SN74HC112 and SN74LS112 by Texas Instruments.

Can’t find the 74×112 anywhere? Then try one of the following IC alternatives:

  • 74×67 – AND-gated master-slave J-K flip-flop.
  • 74×70 – AND-gated positive-edge triggered J-K flip-flop.
  • 74×72 – AND-gated master-slave J-K flip-flop.
  • 74×73 – Dual positive-edge triggered J-K flip-flop.
  • 74×76 – Dual J-K flip-flop.
  • 74×78 – Dual negative-edge triggered J-K flip-flop.
  • 74×107 – Dual negative-edge triggered J-K flip-flop.
  • 74×109 – Dual J-K flip-flop.
  • 74×113 – Dual negative-edge-triggered J-K flip-flop.
  • 74×114 – Dual J-K flip-flop.
  • CD4027 – Dual J-K master-slave flip-flop.
  • CD4095 – Gated J-K flip-flop.
  • CD4096 – Gated J-K flip-flop.

If you can’t find the 74×112 IC in your local electronics store, don’t worry, you’ll most likely find it in one of the stores listed on this page of online stores where you’ll find components and tools for all your electronics projects.

Datasheet for the 74LS112 and 74HC112 chips

Download the PDF datasheet for your version of the 74×112 here:

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