PT7C43390 Datasheet, PDF (11/38 Pages) Pericom Semiconductor Corporation – Real-time Clock Module

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PT7C43390/43390C
Real-time Clock Module
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Minute data (00 to 59): m1, m2, m4, m8, m10, m20, m40
Example: 32 minutes (m1, m2, m4, m8, m10, m20, m40, 0) = (0, 1, 0, 0, 1, 1, 0, 0)
Example: 55 minutes (m1, m2, m4, m8, m10, m20, m40, 0) = (1, 0, 1, 0, 1, 0, 1, 0)
Second data (00 to 59): s1, s2, s4, s8, s10, s20, s40
Example: 19 seconds (s1, s2, s4, s8, s10, s20, s40, 0) = (1, 0, 0, 1, 1, 0, 0, 0)
3.2. Status Register 1
Status register 1 is a 1-byte register that is used to display and set various modes. The bit configuration is shown below.
B1: BLD
This flag is set to "1" when the power supply voltage decreases to the level of detection voltage (VDET) or less. Users can detect a
drop in the power supply voltage. This flag is set to "1" once, is not set to "0" again even if the power supply increases to the level
of detection voltage (VDET) or more. This flag is read-only. When this flag is "1", be sure to initialize. Regarding the operation of
the power supply voltage detection circuit, refer to "Low Power Supply Voltage Detection Circuit".
B2: INT2, B3: INT1
This flag indicates the time set by alarm and when the time has reached it. This flag is set to "1" when the time that users set by
using the alarm interrupt function has come. The INT1 flag at alarm 1 interrupt mode and the INT2 flag at alarm 2 interrupt mode
are set to "1". Set "0" in INT1AE (B5 in the status register 2) or in INT2AE (B1 in the status register 2) after reading "1" in the
INT1 flag or in the INT2 flag. This flag is read-only. This flag is read once, is set to "0" automatically.
B4: SC1, B5: SC0
These flags are SRAM type registers, they are 2 bits as a whole, can be freely set by users.
B6: 12 / 24
This flag is used to set 12-hour or 24-hour mode. Set the flag ahead of write operation of the real-time data register in case of 24-
hour mode.
0: 12-hour mode
1: 24-hour mode
B7: RESET
The internal IC is initialized by setting this bit to "1". This bit is write-only. It is always "0" when reading. When applying the
power supply voltage to the IC, be sure to write "1" to this bit to initialize the circuit. Regarding each status of data after
initialization, refer to "Register Status after Initialization".
3.3. Status Register 2
Status register 2 is a 1-byte register that is used to display and set various modes. The bit configuration is shown below.
B7
B6
B5
B4
B3
B2
B1
B0
INT1FE INT1ME INT1AE 32kE INT2FE INT2ME INT2AE TEST
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W : Read/Write
B0: TEST
This is a test flag. Be sure to set this flag to "0" in use. If this flag is set to "1", be sure to initialize to set "0".
B1: INT2AE, B2: INT2ME, B3: INT2FE
These bits are used to select the output mode for the INT2 pin. Below Table shows how to select the mode. To use an alarm 2
interrupt, set alarm interrupt mode, then access the INT2 register.
Table: Output Modes for INT2 Pin
2015-12-0001
PT0280-8 12/11/15
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