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PT0280(08/09)
Ver: 3
14
Data Sheet
PT7C43390
2-Wire Real-time Clock Module
2)
During realtime data read
Caution 1. When changing an output mode, give care to the state of INT1 register_1 (or INT1 register_2) and the output.
2. If per-minute edge interrupt output or per-minute steady interrupt output is chosen, INT1 register_1 (or INT1
register_2) has no meaning.
6.
During power-on detector operation
When power is applied to this IC, power-on detection circuit operates, status register_1 is set to “80h” (bit 7 (POC flag) of status
register_1 is set to 1) via the power-on detection circuit, and a 1Hz clock is output from the INT1 pin.
Clock adjustment function
A clock adjustment function is provided to logically perform slow/fast adjustment of the 32kHz clock and correct a slow/fast
clock with high accuracy. Use the clock adjustment register to set this function. When not using this function, be sure to set it to
00h.
The clock adjustment register value is calculated by the following expression.
1.
If current oscillation frequency > target frequency (in case the clock is fast)
Caution The figure range which can be corrected is that the calculated value is from 0 to 64.
*1. The register value is the value set to the clock adjustment register. Set the binarized value of this value to the clock
adjustment register.
*2. This is the measurement value of the signal that is output to the INT1 (PT7C43390) or INT2 pin when 1Hz clock
output setting is made.
32kE = 0, INT1ME = 0, INT1FE = 1, INT1 register_1 is 01h (for the INT1 pin)
INT2ME = 0, INT2FE = 1, INT1 register_2 is 01h (for the INT2 pin)
*3. This is the frequency to be adjusted by using the clock adjustment function.
*4. For the minimum resolution, 3.052 ppm or 1.017 ppm can be set using B7 of the clock adjustment register. When B7
is 0, 3.052 ppm is set and logical slow/fast adjustment is performed every 20 seconds. When B7 is 1, 1.017 ppm is set
and logical slow/fast adjustment is performed every 60 seconds.