Qwiic RTC - RV-1805

SKU: SPX-14642 Brand: Sparkfun

Retired Product

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This product has been retired. It is no longer available, but this page has been kept for reference.

The Qwiic RTC from SparkFun is a very unique and exciting Real Time Clock. It is extremely precise (within 3 minutes over a year!), extremely low power (less than 22nA!) and has all the necessary oscillators and back-up power making it very compact.

The RV-1805 from Micro Crystal has not one, but two internal oscillators: a 32.768kHz tuning fork crystal and a low power RC based oscillator. The RV-1805 automatically switches between oscillators using the more precise crystal to correct the RC oscillator every few minutes. This allows the RTC to maintain a very accurate date and time with the worst case being +/- about 3 minutes over a year. Very few RTCs can come close to this.

The RV-1805 and the library we’ve written operate the RTC at 22nA. This is extremely low power. No external battery needed! We’ve included a 0.22F super cap on the Qwiic RTC. This should maintain the RTC for over 170 days (nearly 6 months) but we have not had 6 months to test this. For now, we guarantee the super cap will maintain the RTC for over a month. That means you can let board sit with no power or connection to the outside world and the current hour/minute/second/date will be maintained. The RV-1805 RTC has a built in trickle charger: as soon as the RTC is connected to power the super cap will begin to charge and will be fully charged in under 10 minutes. A super cap is superior to coin cells that cannot be charged.

The RV-1805 has an alarm and timer capability. This allows the user to set various alarms and generate interrupts when a certain time is achieved.

Lastly, and perhaps most interestingly the RV-1805 has the ability to switch power to other systems. The RV-1805 has a PSW pin that can sink up to 50mA. This allows it to directly turn on or off a power hungry device such as a microcontroller or RF engine. The RV-1805 can be configured to power up/down the device based on time or external interrupts.

The Qwiic-RTC uses the simple Qwiic interface. No soldering, no voltage translation, no figuring out which pin is SDA or SCL, just plug and go!

Features

Precise time keeping with variance of +/-3minutes across 1 year
Low 22nA standby current
On board 0.22F super cap capable of RTC maintenance for nearly 6 months
Square wave output
Configurable alarm generation
Capable of powering on/off other peripherals with very low power

Documents

Eagle Files
Qwiic RTC Schematic
The Arduino Library for the RV-1805 can be found in the Arduino library manager but the repo is available at the SparkFun RV-1805 Ardiuno Library for those who want to view the inner workings.
Please see the Qwiic-RTC repo for the latest hardware files

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