AB1804-T3 ABRACON, AB1804-T3 Datasheet - Page 3

• Manufacturer Part Number: AB1804-T3
• Description: Real Time Clock Interface I2C HH
• Manufacturer: ABRACON

Specifications of AB1804-T3

• Rohs: yes
• Function: Clock, Calendar, Alarm
• Rtc Bus Interface: I2C
• Time Format: HH
• Supply Voltage - Max: 3.6 V
• Supply Voltage - Min: 1.7 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Package / Case: QFN-16

2.
The AB18XX 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 AB18XX 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 controlled via memory mapped registers. These registers are accessed using either an I
serial interface (e.g., in the AB1805) or a SPI serial interface (e.g., in the AB1815). Each feature group is described briefly
below.
The baseline timekeeping feature group supports the standard 32 kHz crystal (XT) oscillation mode for maximum frequency
accuracy with an ultra-low current draw of 55 nA. An extended calibration mode enables low jitter digital calibration to an
accuracy of ±2 ppm over a range of -614 ppm to +244 ppm. The baseline timekeeping feature group also includes a standard
set of counters monitoring hundredths of a second up through centuries. A complement of countdown timers and alarms may
additionally be set to initiate interrupts or resets on several of the outputs.
The advanced timekeeping feature group supports two additional oscillation modes: 1) RC oscillator mode, and 2) auto-
calibration mode. At only 15 nA, the temperature-compensated ±10% RC oscillator mode provides an even lower current
draw than the XT oscillator for applications with reduced frequency accuracy requirements. A proprietary calibration
algorithm allows the AB18XX to digitally tune the RC oscillator frequency with accuracy as low as ±2 ppm at a given
temperature and very low calibration jitter. In autocalibration mode, the RC oscillator is used as the primary oscillation
source and is periodically calibrated against the XT oscillator. Autocalibration may be executed every autocalibration period
(ACP) of 8.5 minutes or 17 minutes and may also be initiated via software. This mode enables average current draw of only
20 nA with frequency accuracy similar to the XT oscillator. The advanced timekeeping feature group also includes a rich set
of input and output configuration options that enables the monitoring of external interrupts (e.g., pushbutton signals), the
generation of clock outputs, and watchdog timer functionality.
Date of Issue: Sept. 10
AB18XX Functional Description
Page (2) of (13)
nEXTR
SDA/O
EXTI
nCE
SCL
WDI
SDI
XO
XI
th
RC Osc
XT Osc
, 2012
Interface
Calibration Engine
I2C/SPI
Reset
VCC VBAT
Divider
Divider
Control
Power
Real Time Clock Module
VSS
Abracon Drawing #
Compare
Analog
AB18XX Series
3.0 x 3.0 mm
Weekdays
Seconds
Int/Clock
Minutes
Months
Control
100ths
Alarms
Hours
Years
Timer
Days
WDT
RAM
FOUT/nIRQ
PSW/nIRQ2
nTIRQ
CLKOUT/nIRQ3
nRST
Revision #: Initial Release
ESD Sensitive
2
C