NXP PCF2127 – Lord of the Time

Lord of the time

Adding real time clock information to microcontroller driven systems is problematic. As time goes by, small errors in computing routines add up. Given that users hate entering system times, a real-time element is valuable.

NXP – once Philips Semiconductors – is an old hand in the space of real time clocks, making the PCF2127 a classic. Our figure shows a basic application circuit taken from the application note.

The extra battery ensures timing continuity if system power is unavailable

Let us start out with the most important question: the part is pretty accurate. The small version PCF2127AT promises a three PPM accuracy from -15 to 60°C, while the PCF2127T achieves the same from -30 to 80°C.

A question of complication! RTC ICs work with some kind of serial interface. Given that NXP developed the I2C protocol, the chip makes for a great I2C real-time clock IC. Furthermore, the chip can also work as an SPI real-time clock – the figures show two operating modes.

The PCF2127 makes for a great SPI real time clock

Can also handle the I2C protocol perfectly

In addition to providing a simple incrementing time keeper, the chip also has a calendar system. It even takes care of leap year computations, thereby allowing you to use microcontroller space for other tasks.

Finally, a timestamp function emits a periodic signal. This is useful smart meters, where periodic wake up can be handled via an interrupt generated by the real-time clock IC.

Sadly, developers who still hand-prototype the circuits won’t be happy. The IC comes in SO16 and SO20 variants, both of which are priced similarly.

Given that NXP has a long tradition of designing sensors, the Dutch could not resist adding a temperature sensor and 512 bytes of static RAM. This allows you to store a small amount of information in a remanent fashion. Finally, the chip can also supervise the battery voltage – the circuit can inform the user if the backup battery runs low.

Recent Articles
Digital Aggregators: Benefits of sourcing electronic components through them
Who are digital aggregators? An aggregator is often considered a distributor of data and in this context digital aggregators can be described as online web platforms... Read Article
Monolithic Power Systems’ Range with Farnell
Monolithic Power Systems (MPS) specialise in high-performance, integrated power solutions providing small, easy-to-use energy efficient solutions for industrial applications such as telecom infrastructures, cloud computing, automotive, as... Read Article
15% OFF Interconnect & Electromechanical at Future Electronics
The kind of deal you can’t miss  Electromechanical  Get the most out of your mechanical devices with a wide selection of electromechanical products offering nothing but... Read Article
Wide Bandgap Solutions
Featured Articles Silicon Carbide (SiC) and Gallium Nitride (GaN) are the next generation materials for high performance power conversion and electric vehicles. These wide bandgap (WBG)... Read Article
PS5 & XBOX Series X Giveaway
Traco Power & oemsecrets giveaway In our latest competition, we’ve teamed up with Traco Power to give 2 lucky subscribers the chance to win the latest... Read Article
November 2020 Deals from oemsecrets.com
Latest distributor offers and discount codes using oemsecrets.com Below are some of the discounts and offers exclusively available to our subscribers who search and purchase parts... Read Article