AB18X5 Real-Time Clock with Power

Management Family

Date of Issue: October 16, 2014

3.0 x 3.0 mm

Page 3 of 37

Abracon Drawing #453568

Revision: C

2. Functional Description

Figure 1 illustrates the AB18X5 functional design.

Figure 1. Detailed Block Diagram

AB18X5 serves as a companion part for host processors including microcontrollers, radios, and digital

signal processors. It tracks time as in a typical RTC product and additionally provides unique power

management functionality that makes it ideal for highly energy-constrained applications. To support such

operation, the AB18X5 includes 3 distinct feature groups: 1) baseline timekeeping features, 2) advanced

timekeeping features, and 3) power management features. Functions from each feature group may be

(e.g., in the AB1805) or a SPI serial interface (e.g., in the AB1815). Each feature group is described briefly

below and in greater detail in subsequent sections.

The baseline timekeeping feature group supports the standard 32.786 kHz crystal (XT) oscillation mode for

maximum frequency accuracy with an ultra-low current draw of 55 nA. The baseline timekeeping feature

group also includes a standard set of counters monitoring hundredths of a second up through centuries. A

XT Osc

RC Osc

Divider

Seconds

Minutes

Hours

Days

Weekdays

Months

Years

Power

Control

VCC VBAT

I2C/SPI

Interface

SCL

SDA/O

Control

Alarms

Int/Clock

FOUT/nIRQ

PSW/nIRQ2

VSS

CLKOUT/nIRQ3

SDI

nCE

WDI

Reset

nEXTR

nRST

RAM

XO

XI

nTIRQ

Timer

WDT

100ths

Divider

Calibration Engine

EXTI

Analog

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