I²C Real-Time Clock (RTC) Selection: Ultra-Low-Power vs Precision
Timekeeping current, temp-comp accuracy, PCF8563/DS3231 matches
For battery devices, RTC selection hinges on timekeeping current (runtime) and temperature-compensation accuracy. Micro Crystal RV-series modules embed a 32.768kHz crystal, spanning ultra-low-power to high-precision TCXO, with matches for the DS3231/PCF8563. Organized by need below.
① Ultra-low-power (battery/coin-cell)
Lower timekeeping current = longer battery life; the RV-3028-C7 at ~45nA is among the lowest.
~45nA ultra-low-power, with EEPROM and UNIX-time.
② High precision / temperature-compensated
For wide-temperature stability, choose a temp-compensated (TCXO/DTCXO) part.
Temp-compensated high-accuracy I²C RTC.
DTCXO ±3ppm high accuracy.
③ Basic / PCF8563-compatible
If your design uses the PCF8563, the RV-8564 is register/address-compatible — firmware ports.
PCF8563-compatible, basic low cost.
④ Bare crystal (for an MCU’s own RTC)
If you use the MCU’s built-in RTC, you only need a 32.768kHz crystal as the clock source.
2.0×1.2mm 32.768kHz tuning-fork crystal.
Cross-references
Related guides
Frequently asked questions
What replaces the DS3231? ▾
For ultra-low-power choose the RV-3028-C7 (~45nA vs DS3231 ~840nA, but no TCXO wide-temp); to keep wide-temp precision choose a temp-comp part like the RV-8803-C7. Not pin-compatible — port firmware.
Which Micro Crystal matches the PCF8563? ▾
The RV-8564 is register- and I²C-address (0x51)-compatible with the PCF8563, so existing firmware ports; only the package differs (ceramic module), so re-layout.
Not sure which part fits?
Tell us your application and constraints — our engineers will recommend a part and quote stock, pricing, and lead time.
Request a Quote