NXP Semiconductors K22F series, Reference Manual, Page: 1051 / 1407

Chapter 42
Real Time Clock (RTC)
42.1 Introduction
NOTE
For the chip-specific implementation details of this module's
instances, see the chip configuration information.
42.1.1 Features
The RTC module features include:
• Independent power supply, POR, and 32 kHz crystal oscillator
• 32-bit seconds counter with roll-over protection and 32-bit alarm
• 16-bit prescaler with compensation that can correct errors between 0.12 ppm and
3906 ppm
• Register write protection
• Lock register requires VBAT POR or software reset to enable write access
• Access control registers require system reset to enable read and/or write access
• 1 Hz square wave output with optional interrupt
42.1.2 Modes of operation
The RTC remains functional in all low power modes and can generate an interrupt to exit
any low power mode. It operates in one of two modes of operation: chip power-up and
chip power-down.
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 1051