PCF2129AT/2,518 NXP Semiconductors, PCF2129AT/2,518 Datasheet - Page 20

• 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
8.6 Oscillator stop detection function
The PCF2129AT has an on-chip oscillator detection circuit which monitors the status of
the oscillation: whenever the oscillation stops, a reset occurs and the oscillator stop flag
OSF (in register Seconds) is set logic 1.
Fig 9.
•
•
V
(= 2.5 V)
(= 1.2 V)
th(sw)bat
Power-on:
a. The oscillator is not running, the chip is in reset (OSF is logic 1).
b. When the oscillator starts running and is stable after power-on, the chip exits from
c. The flag OSF is still logic 1 and can be cleared (OSF set logic 0) by command.
Power supply failure:
a. When the power supply of the chip (V
b. When the power supply returns to normal operation, the oscillator starts running
c. The flag OSF is still logic 1 and can be cleared (OSF set logic 0) by command.
(1) Theoretical state of the signals since there is no power.
(2) The oscillator stop flag (OSF), set logic 1, indicates that the oscillation has stopped and a reset has
V
OSF
V
V
V
BAT
reset.
value (V
again, the chip exits from reset.
DD
low
SS
occurred since the flag was last cleared (OSF set logic 0). In this case, the integrity of the clock
information is not guaranteed. The OSF flag is cleared by command.
Power failure event due to battery discharge: reset occurs
V
low
All information provided in this document is subject to legal disclaimers.
BBS
), typically 1.2 V, the oscillator stops running and a reset occurs.
V
BBS
V
BBS
Rev. 5 — 12 February 2013
battery discharge
BBS
Integrated RTC, TCXO and quartz crystal
, see
internal power supply
(1)
Section
V
BBS
8.5.2) drops below a certain
PCF2129AT
© NXP B.V. 2013. All rights reserved.
V
V
V
BAT
DD
SS
(2)
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