PCF2127 View Datasheet(PDF) - NXP Semiconductors.
Part Name
Description
MFG CO.
'PCF2127' PDF : 101 Pages View PDF
NXP Semiconductors
PCF2127
Accurate RTC with integrated quartz crystal for industrial applications
• watchdog timer
• alarm
• timestamp
• battery switch-over
• battery low detection
The control bit TI_TP (register Watchdg_tim_ctl) is used to configure whether the
interrupts generated from the second/minute timer (flag MSF in register Control_2) and
the countdown timer (flag CDTF in register Control_2) are pulsed signals or a
permanently active signal. All the other interrupt sources generate a permanently active
interrupt signal which follows the status of the corresponding flags. When the interrupt
sources are all disabled, INT remains high-impedance.
• The flags MSF, CDTF, AF, TSFx, and BF can be cleared by command.
• The flag WDTF is read only. How it can be cleared is explained in Section 8.11.6.
• The flag BLF is read only. It is cleared automatically from the battery low detection
circuit when the battery is replaced.
8.13.1 Minute and second interrupts
Minute and second interrupts are generated by predefined timers. The timers can be
enabled independently from one another by the bits MI and SI in register Control_1.
However, a minute interrupt enabled on top of a second interrupt cannot be
distinguishable since it occurs at the same time.
The minute/second flag MSF (register Control_2) is set logic 1 when either the seconds or
the minutes counter increments according to the enabled interrupt (see Table 82). The
MSF flag can be cleared by command.
Table 82.
MI
0
1
Effect of bits MI and SI on pin INT and bit MSF
SI
Result on INT
0
no interrupt generated
0
an interrupt once per minute
0
1
an interrupt once per second
1
1
an interrupt once per second
Result on MSF
MSF never set
MSF set when minutes
counter increments
MSF set when seconds
counter increments
MSF set when seconds
counter increments
When MSF is set logic 1:
• If TI_TP is logic 1, the interrupt is generated as a pulsed signal.
• If TI_TP is logic 0, the interrupt is permanently active signal that remains until MSF is
cleared.
PCF2127
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 8 — 19 December 2014
© NXP Semiconductors N.V. 2014. All rights reserved.
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