What is RTC?

Introduction: This article explains what an RTC is. If you're not sure, don't worry — we'll break it down in a simple and friendly way. Let's dive in and learn something new together!

1. What is RTC – An Introduction

RTC stands for Real-Time Clock. It's an electronic component that keeps track of time, much like a regular clock. Usually, it's an integrated circuit, which is why it's also known as a clock chip. RTCs are widely used in consumer electronics to provide accurate time information or serve as a time reference for other systems. Most modern RTCs use high-precision crystal oscillators as their time source.

2. What is RTC – Key Advantages

The RTC provides a stable time signal for the rest of the system. While a system can calculate time without an RTC, using one offers several benefits:

• Low power consumption, especially when powered by a backup battery.
• Allows the main system to focus on more critical tasks.
• Can be more accurate than other timing methods in certain situations.

For example, when paired with a GPS receiver, an RTC can help reduce boot-up time by comparing the current time with the last received data. If the difference is within a few hours, the previous ephemeris data remains valid.

3. What is RTC – Performance Characteristics

RTC chips often have a backup power source to keep running even when the main power is off. Their performance is typically measured by:

• Control method: Two-wire, three-wire, or four-wire systems.
• Crystal type: Built-in or external oscillators.
• Power consumption, time adjustment range, accuracy, and whether it includes a TTF (Time-to-Frequency) function.

4. What is RTC – Main Functions

The primary function of an RTC is to maintain accurate time up to the year 2099. The matching capacitor plays a crucial role in ensuring the crystal oscillator works correctly with the RTC. Some RTCs come with built-in capacitors, like the H1208 model, which helps maintain consistent accuracy. Not all RTCs perform equally well—some may run fast, while others may lag.

Further Reading:

• Cymbet Introduces Ultra Low Power EnerChip RTC
• Backup Power Supply for Microcontroller (MCU) and Real-Time Clock (RTC)
• STM32 Learning Again – Real Time Clock (RTC)

Crystal oscillator