pcf2129a NXP Semiconductors, pcf2129a Datasheet - Page 15

• Manufacturer Part Number: pcf2129a
• Description: Integrated Rtc, Tcxo And Quartz Crystal
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCF2129A_1
Product data sheet
8.5.1.1 Standard mode
8.5.1.2 Direct switching mode
When a power failure condition occurs and the power supply switches to the battery the
following sequence occurs:
The interface is disabled in battery backup operation:
If V
If V
If V
If V
1. The battery switch flag BF (register Control_3) is set logic 1.
2. An interrupt is generated if the control bit BIE (register Control_3) is enabled
3. If the control bit BTSE (register Control_3) is logic 1, the timestamp registers store the
4. The battery switch flag BF is cleared via the interface; it must be cleared to clear the
Fig 4.
•
•
V
DD
DD
DD
DD
DD
V
(see
time and date when the battery switch occurred (see
interrupt.
Interface inputs are not recognized, preventing extraneous data being written to the
device
Interface outputs are high-impedance
(= 2.5 V)
th(sw)bat
(= 0 V)
> V
< V
> V
< V
V
V
INT
BAT
DD
BF
Section
Battery switch-over behavior in standard mode with bit BIE logic 1 (enabled)
BAT
BAT
BAT
BAT
backup battery operation
OR V
AND V
the internal power supply is V
the internal power supply is V
8.12.6).
V
DD
BBS
DD
Rev. 01 — 13 January 2010
> V
< V
th(sw)bat
th(sw)bat
the internal power supply is V
the internal power supply is V
internal power supply (= V
DD
BAT
Integrated RTC, TCXO and quartz crystal
.
.
BBS
Section
)
DD
BAT
8.11.4).
.
PCF2129A
.
cleared via interface
© NXP B.V. 2010. All rights reserved.
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V
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BBS