AB1804-T3 ABRACON, AB1804-T3 Datasheet - Page 4

• 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

Power management features built into the AB18XX enable it to operate as a backup device in both line-powered and battery-
powered systems. An integrated power control module automatically detects when main power (VCC) falls below a
digitally-selectable threshold and switches to backup power (VBAT). Up to 256B of ultra-low leakage RAM enable the
storage of key parameters when operating on backup power.
The AB18XX is the first RTC to incorporate a number of more advanced power management features. In particular, the
AB18XX includes a finite state machine (integrated with the Power Control block) that can control a host processor as it
transitions between sleep/reset states and active states. Digital outputs can be configured to control the reset signal or
interrupt input of the host controller with digitally-tunable timing. The AB18XX additionally integrates a power switch with
<1 Ω impedance that can be used to cut off ground current on the host microcontroller and reduce sleep current to <1 nA.
The AB18XX parts can wake-up a sleeping system using internally generated timing interrupts or externally generated
interrupts generated by digital inputs (e.g., using a pushbutton).
seamlessly power down host processors, leaving only the energy-efficient AB18XX chip awake. The AB18XX also includes
digitally-tunable voltage monitoring for brown-out detection and power-on reset.
3.
The AB18XX enables a variety of system implementations in which the AB18XX can control power usage by other elements
in the system. This is typically used when the entire system is powered from a battery and minimizing total power usage is
critical. The backup RAM in the AB18XX can be used to hold key MCU parameters when it is powered down.
3.1
In the recommended implementation, the internal power switch of the AB18XX is used to completely turn off the MCU
and/or other system elements. In this case the PSW/nIRQ2 output is configured to generate the Sleep function. Under
normal circumstances, the PSW/nIRQ2pin is pulled to VSS with less than 1 ohm of resistance, so that the MCU receives full
power. The MCU initiates a SLP operation, and when the AB18XX enters Sleep Mode the PSW/nIRQ2 pin is opened and
power is completely removed from the MCU. This results in significant additional power savings relative to the other
alternatives. A variety of interrupts, including alarms, timers and external interrupts created by a pushbutton as shown, may
be used to exit Sleep Mode and restore MCU power. The RAM of the AB18XX may be used to retain critical MCU
parameters.
Date of Issue: Sept. 10
AB18XX Example Applications
VSS Power Switched
Page (3) of (13)
th
, 2012
R
EXTI
XO
XI
Real Time Clock Module
AB18XX
AM18XX
Abracon Drawing #
VSS
AB18XX Series
3.0 x 3.0 mm
PSW/nIRQ2
FOUT/nIRQ
VCC
The aforementioned functionality enables users to
I2C/SPI
VSS
IRQ
Revision #: Initial Release
MCU
VCC
ESD Sensitive