PCF2129AT/2,518 NXP Semiconductors, PCF2129AT/2,518 Datasheet - Page 21

• 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
PCF2129AT
Product data sheet
8.7.1 Power-On Reset (POR)
8.7.2 Power-On Reset Override (PORO)
8.7 Reset function
The PCF2129AT has a Power-On Reset (POR) and a Power-On Reset Override (PORO)
function implemented.
The POR is active whenever the oscillator is stopped. The oscillator is also considered to
be stopped during the time between power-on and stable crystal resonance (see
Figure
supply voltage. Whenever an internal reset occurs, the oscillator stop flag is set (OSF set
logic 1).
After POR, the following mode is entered:
The register values after power-on are shown in
The POR duration is directly related to the crystal oscillator start-up time. Due to the long
start-up times experienced by these types of circuits, a mechanism has been built in to
disable the POR and therefore speed up the on-board test of the device.
Fig 10. Dependency between POR and oscillator
Fig 11. Power-On Reset (POR) system
•
•
•
•
•
32.768 kHz CLKOUT active
Power-On Reset Override (PORO) available to be set
24 hour mode is selected
Battery switch-over is enabled
Battery low detection is enabled
10). This time may be in the range of 200 ms to 2 s depending on temperature and
oscillation
internal
reset
V
DD
All information provided in this document is subject to legal disclaimers.
SDA/CE
SCL
Rev. 5 — 12 February 2013
OSCILLATOR
POR_OVRD
OVERRIDE
RESET
CLEAR
chip in reset
0 = override inactive
1 = override active
0 = clear override mode
1 = override possible
0 = stopped, 1 = running
osc stopped
Integrated RTC, TCXO and quartz crystal
Table
5.
chip not in reset
001aaj324
PCF2129AT
reset
© NXP B.V. 2013. All rights reserved.
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t
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