555 Timer vs 556 Timer: Key Differences Explained

This article clarifies the distinctions between the 555 timer IC and the 556 timer IC, focusing on their pin diagrams and functionalities.

555 Timer IC

The 555 timer is a ubiquitous integrated circuit used in a variety of timer, pulse generation, and oscillator applications.

556 Timer IC

The 556 timer IC is essentially a dual version of the 555 timer. It contains two independent 555 timer circuits within a single package. This allows for more complex timing circuits within a single IC. It is housed in a 14-pin DIL (Dual In-Line) package.

The two timer circuits within the 556 IC can be used completely independently of each other. Importantly, each timer circuit shares the same electrical characteristics as the standard 555 timer IC. This makes it a convenient choice when you need two timers in a single application, saving space and potentially reducing component count.

Key Differences:

• Number of Timers: The primary difference is that the 555 timer IC contains a single timer circuit, while the 556 timer IC contains two independent timer circuits.
• Pin Count: The 555 timer typically comes in an 8-pin package, while the 556 timer comes in a 14-pin package to accommodate the additional timer circuit.
• Functionality: The individual timer circuits within the 556 function identically to a 555 timer. The 556 simply provides two of these in one package.