What's the difference between 74HC595 and 74HC164?

Hey guys, if you are an electronic DIY lover, you will always find a lot of similar or interchangeable components, which have subtle differences in the specs or features, and can therefore lead to the wrong application. 74HC595 and its similar components is an example I'm going to mention today.

74HC595 and 74HC164, 74LS595 and MCP23017, except for the last one, the former three ICs are shift registers that can drive LEDs, especially 74HC595; it can drive LEDs directly. Those components are alike in some way and have their own distinguishing features as well.

So let's explore these four ICs specifications and compare them to see what are their differences.

74LS595 is TTL-based, fast, uses more power and is older.

74HC595 is CMOS-based, fast, uses less power, and is the most up-to-date version.

To be more specific, the LS series is built with bipolar transistors and is based on TTL (total transistor logic) (BJT). BJTs were among the first transistors used in integrated circuits.

74HC164 is serial in and parallel out, like the CD4015, but 74HC595 is faster and has lower voltage.

The difference between the 74HC595 and the 74HC164 is that the 74HC164 does not buffer the data (internal space existed on the 74HC595), so the LED FLASHES as it drags the bits to the tip-toe, giving the flashing effect seen in the 74HC164 but not on the 74HC595.

To be short, 74HC595 is a shift register, while MCP23017 is an IO Expander.

If you want to drive LEDs directly you could just go for 74HC595, but you want a component that is more flexible in the projects, MCP23017 is a good choice, what’s more, they can pretty much use the same software.

About shift register and IO Expander, the main differences are speed complexity in driving them.

Alright, that's all for today. I hope this blog helps!