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
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Fig 47. Bus protocol, reading from RAM
DDD
9.3 Bus communication and battery backup operation
To save power during battery backup operation (see Section 8.6.1), the bus interfaces are
inactive. Therefore the communication via I2C- or SPI-bus should be terminated before
the supply of the PCF2127 is switched from VDD to VBAT.
The extra power fail detection function (see Section 8.6.3) of the PCF2127 allows early
detection of a dropping VDD. The output on pin PFO indicates to the microcontroller to
terminate the bus communication properly. When the bus communication is not
terminated in a proper way, the time counters get corrupted.
Remark: If the I2C-bus communication was terminated uncontrolled, the I2C-bus has to
be reinitialized by sending a STOP followed by a START after the device switched back
from battery backup operation to VDD supply operation.
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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