PCF2127AT/1,518 NXP Semiconductors, PCF2127AT/1,518 Datasheet - Page 22
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PCF2127AT/1,518
Manufacturer Part Number
PCF2127AT/1,518
Description
IC RTC/CALENDAR TCXO QTZ 20SOIC
Manufacturer
NXP Semiconductors
Type
Clock/Calendar/Alarmr
Datasheet
1.PCF2127AT1518.pdf
(80 pages)
Specifications of PCF2127AT/1,518
Package / Case
20-SOIC (0.300", 7.50mm Width)
Time Format
HH:MM:SS (12/24 hr)
Memory Size
512B
Date Format
YY-MM-DD-dd
Interface
I²C, 2-Wire Serial
Voltage - Supply
1.8 V ~ 4.2 V
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Function
Serial Clock, Timestamp, Timekeeper, Watchdog, Alarm, Calendar, Timer, Timer Interrupt
Rtc Memory Size
512 bytes
Supply Voltage (max)
4.2 V
Supply Voltage (min)
1.8 V
Mounting Style
SMD/SMT
Rtc Bus Interface
I2C
Supply Current
2600 nA
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
NXP Semiconductors
PCF2127A_2
Product data sheet
8.6.4 Extra power fail detection function
The PCF2127A has an extra power fail detection circuit which compares the voltage at the
power fail input pin PFI to an internal reference voltage equal to 1.25 V.
If V
LOW output which requires an external pull-up resistor in any application.
The extra power fail detection function is typically used as a low voltage detection for the
main power supply V
Usually R1 and R2 should be chosen such that the voltage at pin PFI
Fig 8.
Fig 9.
•
•
V
DD
V
PFI
is higher than 1.25 V at start-up
falls below 1.25 V when V
by
(= 2.5 V)
th(bat)low
= V
< 1.25 V the power fail output PFO is driven LOW. PFO is an open-drain, active
V
Equation
BLF
BBS
INT
BAT
Battery low detection behavior with bit BLIE set logic 1 (enabled)
Typical application of the extra power fail detection function
All information provided in this document is subject to legal disclaimers.
1:
DD
(see
Rev. 02 — 7 May 2010
Figure
DD
PCF2127A
falls below a desired threshold voltage, V
(internal)
9).
1.25 V
internal power supply (= V
15
14
PFI
PFO
Integrated RTC, TCXO and quartz crystal
V
V
DD
V
SS
BAT
R1
R2
001aaj678
R PU
BBS
)
PCF2127A
© NXP B.V. 2010. All rights reserved.
th(uvp)
, defined
001aaj322
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