S-35399A02 Datasheet, PDF (34/55 Pages) Seiko Instruments Inc – 2-WIRE REAL-TIME CLOCK

2-WIRE REAL-TIME CLOCK
S-35399A02
Rev.1.0_00
„ 32.768 kHz Output Pins
The S-35399A02 outputs a 32.768 kHz clock pulse from the INT1 , F32K, and FOUT pins. However, do not output 32.768
kHz from these three pins simultaneously because stability of the crystal oscillator is affected.
When using the function to clock-correction or adjusting the oscillation frequency, measure the oscillation frequency under
the usage conditions. For example, when using 32.768 kHz clock pulse which is output from the FOUT pin, measure this IC
while the pulse is being output from the pin.
„ Timing of Clock Output from F32K Pin
The 32.768 kHz clock pulse of the oscillation frequency is output from the F32K pin. The F32K pin has an Nch open-drain
output. When the CTRL pin is in “H”, the clock pulse is output, and when the CTRL pin is in “L” or open, the F32K pin is in
high impedance. To output 32.768 kHz from the F32K pin, set the CTRL pin to “H” when one sec or more has elapsed after
power-on.
CTRL pin
F32K pin
ON
OFF
Figure 38 Timing of Clock Output from F32K Pin
„ Up-Count Operation
The up counter is a 24-bit read-only binary counter. This counter starts counting from “000000h” from power-on and returns
to “000000h” at the next clock after it has reached “FFFFFFh”. A clock pulse is a pulse that is output when the second-data
in the real-time data is “00h”. Therefore, some delay is made in the period that a clock pulse is being output due to Write
timing and Write data. The registers are not initialized unless power-on again, so that users are able to grasp the elapsed
time from power-on up to 30 years. Figure 39 shows the example of timing chart of up counter’s operation.
ON
Power supply
OFF
Write real-time
second data:
20 seconds
Write real-time
second data:
50 seconds
Clock pulse
of real-time
second data
"00h"
40 s 40 s
60 s 20 s 10 s
24-bit binary
up counter
000000 h 000001 h 000010 h
OFF
60 s
60 s
FFFFFF h 000000 h 000001 h
A clock pulse is
60 seconds or more.
A clock pulse is
60 seconds or less.
Figure 39 Timing Chart of 24-Bit Binary Up Counter
34
Seiko Instruments Inc.