STFPC320 STMicroelectronics, STFPC320 Datasheet - Page 27

• Manufacturer Part Number: STFPC320
• Description: Front Panel Controller/driver With Standby Power Management And Real-time Clock
• Manufacturer: STMicroelectronics

STFPC320
6.8
Square wave output
The STFPC320 offers the user a programmable square wave function which is output on the
IRQ_N/SQW pin. RS3-RS0 bits located in 04h register establish the square wave output
frequency. These frequencies are listed in Table below. Once the selection of the SQW
frequency has been completed, the IRQ_N/SQW pin can be turned on or off under software
control with the Square Wave Enable Bit (SQWE) located in register 0Ah. The initial power-
up default for the IRQ_N/SQW output is 32KHz.
Table 5.
RS3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Square wave output frequency
RS2
Square wave bits
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
RS1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
RS0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Real Time Clock (RTC) operation
Frequency
32.768
8.162
4.096
2.048
1.024
None
512
256
128
64
32
16
8
4
2
1
Square wave
Units
kHz
kHz
kHz
kHz
kHz
Hz
Hz
Hz
Hz
Hz
Hz
Hz
Hz
Hz
Hz
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