PCF2129AT/2,518 NXP Semiconductors, PCF2129AT/2,518 Datasheet - Page 5

• Manufacturer Part Number: PCF2129AT/2,518
• Description: Real Time Clock
• Manufacturer: NXP Semiconductors
• Series: PCF2129r

Specifications of PCF2129AT/2,518

• Rohs: yes
• Function: Clock, Calendar, Alarm, Watchdog, Timestamp
• Rtc Bus Interface: I2C, SPI
• Date Format: Binary
• Time Format: Binary
• Supply Voltage - Max: 4.2 V
• Supply Voltage - Min: 1.2 V
• Maximum Operating Temperature: + 60 C
• Minimum Operating Temperature: - 15 C
• Mounting Style: SMD/SMT
• Package / Case: SOP-20
• Battery Backup Switching: Yes
• Factory Pack Quantity: 2000

NXP Semiconductors
8. Functional description
PCF2129AT
Product data sheet
8.1 Register overview
The PCF2129AT is a Real Time Clock (RTC) and calendar with an on-chip Temperature
Compensated Crystal (Xtal) Oscillator (TCXO) and a 32.768 kHz quartz crystal integrated
into the same package.
Address and data are transferred by a selectable 400 kHz Fast-mode I
SPI-bus with separate data input and output (see
SPI-bus is 6.5 Mbit/s.
The PCF2129AT has a backup battery input pin and backup battery switch-over circuit
which monitors the main power supply. backup battery switch-over circuit automatically
switches to the backup battery when a power failure condition is detected (see
Section
interrupted.
A battery low detection circuit monitors the status of the battery (see
the battery voltage drops below a certain threshold value, a flag is set to indicate that the
battery must be replaced soon. This ensures the integrity of the data during periods of
battery backup.
The PCF2129AT contains an auto-incrementing address register: the built-in address
register will increment automatically after each read or write of a data byte up to the
register 1Bh. After register 1Bh, the auto-incrementing will wrap around to address 00h
(see
Fig 3.
•
•
•
The first three registers (memory address 00h, 01h, and 02h) are used as control
registers (see
The memory addresses 03h through to 09h are used as counters for the clock
function (seconds up to years). The date is automatically adjusted for months with
fewer than 31 days, including corrections for leap years. The clock can operate in
12-hour mode with an AM/PM indication or in 24-hour mode (see
The registers at addresses 0Ah through 0Eh define the alarm function. It can be
selected that an interrupt is generated when an alarm event occurs (see
Figure
8.5.1). Accurate timekeeping is maintained even when the main power supply is
Handling address registers
3).
All information provided in this document is subject to legal disclaimers.
Section
Rev. 5 — 12 February 2013
8.2).
address register
1Ah
1Bh
00h
01h
02h
03h
19h
...
auto-increment
Integrated RTC, TCXO and quartz crystal
Section
wrap around
001aaj398
9). The maximum speed of the
PCF2129AT
Section
Section
2
© NXP B.V. 2013. All rights reserved.
C-bus or a 3 line
8.5.3). When
Section
8.8).
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8.9).