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DS-72-31 V.08

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SPI Real-Time Clock/Calendar with Integrated Backup Power

CBC34123 EnerChip™ RTC

Features

• Integrated rechargeable solid state battery with

power-fail detect and automatic switchover, pro-

viding greater than 30 hours of RTC backup

• Smallest commercially available RTC with inte-

grated backup power in compact 5mm x 5mm

1.4mm QFN package

• Temperature compensated charge control

• Integrated EnerChip™ recharged at VDD > 2.5V

• SMT assembly - lead-free reflow solder tolerant

• Real time clock provides year, month, day, week-

day, hours, minutes, and seconds based on a

32.768 kHz quartz crystal

• Resolution: seconds to years

• Watchdog functionality

• Freely programmable timer and alarm with inter-

rupt capability

• 3-line SPI-bus with separate, but combinable

data input and output

• Integrated oscillator load capacitors for C

• Internal Power-On Reset (POR)

• Open-drain interrupt and clock output pins

• Programmable offset register for frequency

adjustment

• Eco-friendly, RoHS compliant - tested

General Description

The EnerChip RTC CBC34123-M5C combines a

Real-Time Clock (RTC) and calendar optimized

for low power applications with an integrated

rechargeable solid state backup battery and all power

management functions. The EnerChip RTC ensures

a seamless transition from main power to backup

power in the event of power loss. The integrated

power management circuit ensures thousands of

charge-discharge cycles from the integrated EnerChip

and manages battery charging, discharge cutoff,

power switchover, and temperature compensation

to maximize the service life of the device. The

CBC34123 provides greater than 30 hours of backup

time in the event main power is interrupted. Typical

blackout times are less than 4 hours. The EnerChip

has extremely low self-discharge, recharges quickly, is

non-flammable, and RoHS-compliant. The EnerChip is

charged automatically anytime VDD is above 2.5V.

Data is transferred serially via a Serial Peripheral

Interface (SPI-bus) with a maximum data rate of 6.25

Mbit/s. Alarm and timer functions provide the option

to generate a wake-up signal on an interrupt pin. An

offset register allows fine tuning of the clock.

5mm x 5mm x 1.4mm 16-QFN Package

Applications

• Wireless sensors and RFID tags

and other

powered, low duty cycle applications.

• Power bridging

to provide uninterruptible RTC

function during exchange of main batteries.

• Consumer appliances

that have real-time

clocks; provides switchover power from main

supply to backup battery.

• Business and industrial systems

such as:

network routers, point-of-sale terminals, single-

board computers, test equipment, multi-function

printers, industrial controllers, and utility meters.

• Time keeping application

• Battery powered devices

• Metering

• High duration timers

• Daily alarms

• Low standby power applications

Preliminary

Figure 1: CBC34123 Pin-out Diagram