pcf2127a NXP Semiconductors, pcf2127a Datasheet - Page 51

• Manufacturer Part Number: pcf2127a
• Description: Integrated Rtc, Tcxo And Quartz Crystal
• Manufacturer: NXP Semiconductors

NXP Semiconductors
Table 55.
[1]
PCF2127A_1
Product data sheet
Bit
STOP
Clock is running normally
0
STOP bit is activated by user. F
1
New time is set by user
1
STOP bit is released by user
0
0
0
0
:
0
0
0
:
0
0
0
:
0
0
F
0
is clocked at 32.768 kHz.
Prescaler bits
F
010000111-010100
XXXXXXXXX-000000
XXXXXXXXX-000000
XXXXXXXXX-000000
XXXXXXXXX-100000
XXXXXXXXX-100000
XXXXXXXXX-110000
:
111111111-111110
000000000-000001
100000000-000001
:
111111111-111111
000000000-000000
100000000-000000
:
111111111-111110
000000000-000001
First increment of time circuits after stop release
0
to F
8.15 STOP bit function
8
- F
9
to F
The function of the STOP bit is to allow for accurate starting of the time circuits. STOP will
cause the upper part of the prescaler (F
are generated. The time circuits can then be set and will not increment until the STOP bit
is released. STOP will not affect the CLKOUT signal but the output of the prescaler in the
range of 32 Hz to 1 Hz (see
The lower stages of the prescaler, F
SPI-bus are asynchronous to the crystal oscillator, the accuracy of re-starting the time
circuits is between 0 and one 64 Hz cycle (0.484375 s and 0.500000 s), see
Figure
[1]
14
32.
0
to F
1 Hz tick
8
001aaj479
are not reset and values cannot be predicted externally
Rev. 01 — 21 January 2010
Time
hh:mm:ss
12:45:12
12:45:12
08:00:00
08:00:00
08:00:00
08:00:00
08:00:00
:
08:00:00
08:00:01
08:00:01
:
08:00:01
08:00:01
:
08:00:01
08:00:02
Figure
31).
0
to F
Comment
prescaler counting normally
prescaler is reset; time circuits are frozen
prescaler is reset; time circuits are frozen
prescaler is now running
0 to 1 transition of F14 increments the time circuits
0 to 1 transition of F14 increments the time circuits
9
8
to F
, are not reset and because the I
14
Integrated RTC, TCXO and quartz crystal
) to be held in reset and thus no 1 Hz ticks
PCF2127A
© NXP B.V. 2010. All rights reserved.
2
C-bus and the
Table 55
51 of 79
and