S35390A datasheet(40/51 Pages) SII

40 / 51 page

FOR AUTOMOTIVE 105°C OPERATION 2-WIRE REAL-TIME CLOCK

S-35390A H Series

Rev.2.2_00

Seiko Instruments Inc.

2. Measurement of oscillation frequency

When the S-35390A H Series is turned on, the internal power-on detector operates and a signal of 1 Hz is output from

the

INT

pin to select the crystal oscillator and optimize the Cg value. Turn the power on and measure the signal with a

frequency counter following the circuit configuration shown in Figure 51.

If 1 Hz signal is not output, the power-on detector does not operate normally. Turn off the power and then turn it on again.

For how to apply power, refer to " Power-on Detection Circuit and Register Status".

Remark If the error range is

±1 ppm in relation to 1 Hz, the time is shifted by approximately 2.6 seconds per month

(calculated using the following mode).

–6 (1 ppm) × 60 seconds × 60 minutes × 24 hours × 30 days = 2.592 seconds

INT1

INT2

SDA

SCL S-35390A H Series

VDD

XOUT

XIN

VSS

1 k

10 k

1 k

Frequency

counter

Open

or pull-up

Figure 51 Configuration of Oscillation Frequency Measurement Circuit

Caution

1. Use a high-accuracy frequency counter of 7 digits or more.

2. Measure the oscillation frequency under the usage conditions.

3. Since the 1 Hz signal continues to be output, initialization must be executed during normal

operation.

S35390A Datasheet(PDF) 40 Page - Seiko Instruments Inc