BQ32002 Datasheet, PDF (7/29 Pages) Texas Instruments – BQ32002 Real-Time Clock (RTC)

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7 Detailed Description
BQ32002
SLUSA96B – AUGUST 2010 – REVISED APRIL 2016
7.1 Overview
The BQ32002 is a real-time clock that features an automatic backup supply with integrated oscillator-fail
detection.
7.2 Functional Block Diagram
V_CC
Place supply-decoupling
capacitor near supply pin
1 µF
V_CC
Use only
super-capacitor
or battery, not
both
V_BACK
.22 F
OSCI
OSCO
Automatic
Backup
Switch
VCORE
Interrupt
Generator
V_CC
IRQ
4.7 NŸ
4.7 NŸ
4.7 NŸ
32-kHz
Oscillator
I2C Register
Interface With
Undervoltage
Lockout
Registers
SCL
SDA
GND
Copyright © 2016, Texas Instruments Incorporated
NOTE: All pullup resistors should be connected to V_CC such that no pullup is applied during backup supply operation.
7.3 Feature Description
7.3.1 IRQ Function
The IRQ pin of the BQ32002 functions as a general-purpose output or a frequency test output. The function of
IRQ is configurable in the device register space by setting the FT, FTF, and OUT bits. On initial power cycles,
the OUT bit is set to one, and the FTF and FT bits are set to zero. On subsequent power-ups, with backup
supply present, the OUT bit remains unchanged, and the FTF and FT bits are set to zero. When operating on
backup supply, the IRQ pin function is unused. IRQ pullup resistor must be tied to V_CC to prevent IRQ operation
when operating on backup supply. The effect of the calibration logic is not normally observable when IRQ is
configured to output 1 Hz. The calibration logic functions by periodically adjusting the width of the 1-Hz clock.
The calibration effect is observable only every eight or sixteen minutes, depending on the sign of the calibration.
Copyright © 2010–2016, Texas Instruments Incorporated
Product Folder Links: BQ32002
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