PCF2127AT/1,518 NXP Semiconductors, PCF2127AT/1,518 Datasheet - Page 35

• Manufacturer Part Number: PCF2127AT/1,518
• Description: IC RTC/CALENDAR TCXO QTZ 20SOIC
• Manufacturer: NXP Semiconductors
• Type: Clock/Calendar/Alarmr

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
8.11.1 Register Watchdg_tim_ctl
8.11 Timer functions
The PCF2127A has two different timer functions, a watchdog timer and a countdown
timer. The timers can be selected by using the control bits WD_CD[1:0] in the register
Watchdg_tim_ctl.
To control the timer functions and timer output, the registers Control_2, Watchdg_tim_ctl,
and Watchdg_tim_val are used.
Table 34.
[1]
Bit
7 to 6 WD_CD[1:0]
5
4 to 2 -
1 to 0 TF[1:0]
•
•
The watchdog timer has four selectable source clocks. It can, for example, be used to
detect a microprocessor with interrupt and reset capability which is out of control (see
Section
The countdown timer has four selectable source clocks allowing for countdown
periods from less than 1 ms to more than 4 hours (see
Default value.
Symbol
TI_TP
Watchdg_tim_ctl - watchdog timer control register (address 10h) bit description
8.11.3)
All information provided in this document is subject to legal disclaimers.
Rev. 02 — 7 May 2010
Value
00
01
10
11
0
1
-
00
01
10
11
[1]
[1]
[1]
Description
watchdog timer disabled;
countdown timer disabled
watchdog timer disabled;
countdown timer enabled
watchdog timer enabled;
countdown timer not available
watchdog timer enabled;
countdown timer not available
the interrupt pin INT is configured to generate a
permanent active signal when MSF and/or CDTF is set
the interrupt pin INT is configured to generate a pulsed
signal when MSF flag and/or CDTF flag is set (see
Figure
unused
timer source clock for watchdog and countdown timer
if CDTIE is set logic 1, the interrupt pin INT is
activated when the countdown timed out
the interrupt pin INT is activated when timed out;
the reset pin RST is activated when timed out;
4.096 kHz
64 Hz
1 Hz
1
⁄
60
Hz
25)
Integrated RTC, TCXO and quartz crystal
Section
PCF2127A
8.11.4)
© NXP B.V. 2010. All rights reserved.
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