7400 Series Guide: 74LS19

The 74LS19 is an inverter chip with Schmitt-trigger inputs.

In this guide, you will learn everything you need to know about this chip and how you can use unknowns in your own projects.

What does the 74HC19 / 74LS19 do?

The 74LS19 gives you six NOT-gates that typically have a 0.8V input hysteresis. And it uses Totem-Pole Outputs.

In the truth table below, you can see what the output will be for any given input:

How To Use This Chip

The 74LS19 comes in a 14-pin package, and you need to connect it to power before you can use it. Like most 7400 ICs, it supports a VCC voltage of 5V.

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). This can differ between models, so check the datasheet of your model to verify.

Once you’ve connected it to power, you can use any of the inverters inside.

74×19 Pinout

The 74LS19 has 14 pins and contains six inverters laid out as shown in the pinout diagram below:

Pin Name	Pin #	Type	Description
1A	1	Input	Input to the first NOT gate.
/1Y	2	Output	Output from the first NOT gate.
2A	3	Input	Input to the second NOT gate.
/2Y	4	Output	Output from the second NOT gate.
3A	5	Input	Input to the third NOT gate.
/3Y	6	Output	Output from the third NOT gate.
GND	7	Power	Connect to ground (GND).
/4Y	8	Output	Output from the fourth NOT gate.
4A	9	Input	Input to the fourth NOT gate.
/5Y	10	Output	Output from the fifth NOT gate.
5A	11	Input	Input to the fifth NOT gate.
/6Y	12	Output	Output from the sixth NOT gate.
6A	13	Input	Input to the sixth NOT gate.
VCC	14	Power	Positive power supply (VCC). Connect to +5V power.

Alternatives and Equivalents for 74LS19

There are many versions of the 74×19 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:

• 74HC19 (High-speed CMOS)
• 74HCT19 (High-speed CMOS, TTL compatible)
• 74LS19 (High-speed TTL)
• 74LVC19 (Low Voltage TTL)
• 74AC19 (Advanced CMOS)
• 74ALS19 (Advanced Low-Power Schottky TTL)
• 74F19 (Very High Speed)
• 74C19 (CMOS, similar to the 4000-series)

Some manufacturers also add a prefix, such as the SN74LS19 by Texas Instruments.

Can’t find the 74×19 anywhere? Then try one of the following IC alternatives:

• 74×04 – Hex inverters.
• 74×05 – Hex inverters (with open-collector outputs).
• 74×14 – Hex inverters (with Schmitt-trigger inputs).
• CD4049 – Hex inverters (with high sink current).
• CD4069 – Hex inverters
• CD40106 – Hex inverters (with Schmitt-trigger inputs).

If you can’t find the 74×19 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 74LS19

Download the PDF datasheet for your version of the 74LS19 here:

• SN74LS19 (Texas Instruments)