This energy-efficient, autonomous timing circuit features a time stamp, battery back-up,
two alarms, and resolution up to 1/100 s, plus 64 Bytes of battery-buffered RAM.
NXP RTC
PCF85363
RTC with battery back-up switch, time
stamp, and RAM
KEY FEATURES
` Multiple operating modes
- Clock (seconds to 99 years)
- Stopwatch or elapsed-time counter (1/100 s to 999,999 h)
- Watchdog in parallel
` Battery input with a voltage can be higher or lower than V
DD
` Time-stamp input with three time-stamp registers
` 64 Bytes of general-purpose RAM (battery-buffered)
` Two independent alarms
` Electronic frequency tuning via command
` Large clock operating voltage range (0.9 to 5.5 V)
` Ideal for battery-backed operation (I
DD
= ~0.27 μA)
` 400 kHz two-line I
2
C-bus interface (at V
DD
= 1.8 to 5.5 V)
` TSSOP8, TSSOP10, and tiny DFN2626 packages
APPLICATIONS
` Inkjet and laser printers
` Digital still and video cameras
` Handheld and mobile devices
` Industrial equipment
` Home automation
` Alarm systems
` Self-care medical devices
` Eco-friendly heating control
The NXP PCF85363 is a CMOS real-time clock (RTC) and
calendar, optimized for low power consumption, that switches
automatically to battery power when main power is lost.
The PCF85363 can be configured as a stopwatch (or elapsed-
time counter) with a resolution of up to 1/100 s. Three time
stamps make it easy to register special events, and the
device can also register tamper detection or time of battery
switchover.
The integrated RAM block of 64 Bytes is ideal for storing
parameters during system power-down. The battery keeps the
RTC running and maintains memory content.
A sophisticated battery-backup circuit improves power
efficiency. The circuit makes it possible to use a battery with a
nominal voltage that is higher or lower than the regular supply
voltage. For example, in a system that uses a V
DD
of 2.5 V, a
lithium battery of 3 V can be used as a backup.
* Released on request ** RTC sister family
www.nxp.com
© 2014 NXP Semiconductors N.V.
All rights reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The
information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and
may be changed without notice. No liability will be accepted by the publisher for any consequence of its use. Publication thereof
does not convey nor imply any license under patent- or other industrial or intellectual property rights.
Date of release: June 2014
Document order number: 9397 750 17569
Printed in the Netherlands
The PCF85363 can be used to perform standard RTC
functions, such as tracking the actual time and date, or acting
as a reference timer. To support power management, the
PCF85363 can be used to wake the microcontroller from
hibernation mode. In systems that use a PLL, it can serve
as a system reference clock for the PLL input. The PCF85363
can also be used as a Watchdog timer, or as an activation timer
to start measurements or initiate other functions.
Interrupts can be selected for every second, minute, or hour,
and there can be up to two alarms on two independent
outputs. The designer can choose between a permanent or a
pulse interrupt signal, or can opt for an interrupt from a time-
stamp event.
A dedicated offset register can be programmed to
compensate for tolerance in the quartz frequency tolerance.
The PCF85263ATT version is housed in an TSSOP8 package,
while the PCF85263ATT1 comes in a TSSOP10. Both are
equipped with an I
2
C Fast-mode (Fm) interface.
Versions equipped with an SPI (PCF85363B) interface are
available on request.
EVALUATION BOARDS
The PCF85363A is supported by an evaluation board,
equipped with battery backup and a switch to simulate time
stamps. Start-up is simple – just connect the power supply and
use the serial interface to initiate communications for setting
the actual time and to access the RTC.
PCF85363 application PCF85363 evaluation board I
2
C (OM13514)
PCF85363 block diagram
Selection guide
Product number PCF85363ATT PCF85363ATT1 PCF85363ATL PCF85363B family * PCF85263 family **
Interface FM I
2
C-bus FM I
2
C-bus FM I
2
C-bus SPI I
2
C /SPI
Battery switch, interrupt/CLK output X X X X X
Time-stamp input, separate CLK output
RAM
- X X X (X)
64 Byte 64 Byte 64 Byte 64 Byte 1
Package
(mm)
TSSOP-8 TSSOP-10 DFN2626-10 (2.6 x 2.6 x 0.5) DFN2626-10, TSSOP-10 DFN2626-10, TSSOP8, 10