M41ST87YMX6TR View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
M41ST87YMX6TR
STMicroelectronics
'M41ST87YMX6TR' PDF : 42 Pages View PDF
M41ST87Y, M41ST87W
Square Wave Output
The M41ST87Y/W offers the user a programma-
ble square wave function which is output on the
SQW/FT pin. RS3-RS0 bits located in 13h estab-
lish the square wave output frequency. These fre-
quencies are listed in Table 9. Once the selection
of the SQW frequency has been completed, the
SQW/FT pin can be turned on and off under soft-
ware control with the Square Wave Enable Bit
(SQWE) located in Register 0Ah.
The SQW/FT output is programmable as an N-
channel, open drain output driver, or a full-CMOS
Table 9. Square Wave Output Frequency
Square Wave Bits
RS3
RS2
RS1
0
0
0
0
0
0
0
0
1
0
0
1
0
1
0
0
1
0
0
1
1
0
1
1
1
0
0
1
0
0
1
0
1
1
0
1
1
1
0
1
1
0
1
1
1
1
1
1
output driver. By setting the Square Wave Open
Drain Bit (SQWOD) to a '1,' the output will be con-
figured as an open drain (with IOL as specified in
Table 17., page 37). When SQWOD is set to '0,'
the output will be configured as full-CMOS (sink
and source current as specified in Table
17., page 37).
Note: When configured as open drain (SQWOD =
'1'), the SQW/FT pin requires an external pull-up
resistor.
Square Wave
RS0
Frequency
Units
0
None
–
1
32.768
kHz
0
8.192
kHz
1
4.096
kHz
0
2.048
kHz
1
1.024
kHz
0
512
Hz
1
256
Hz
0
128
Hz
1
64
Hz
0
32
Hz
1
16
Hz
0
8
Hz
1
4
Hz
0
2
Hz
1
1
Hz
Full-time 32kHz Square Wave Output
The M41ST87Y/W offers the user a special 32kHz
square wave function which defaults to output on
the F32k pin (Pin 21) as long as VCC ≥ VSO, and the
oscillator is running (ST Bit = '0'). This function is
available within one second (typ) of initial power-
up and can only be disabled by setting the 32kE
Bit to '0' or the ST Bit to '1.' If not used, the F32k pin
should be disconnected and allowed to float.
Note: The F32k pin is an open drain which requires
an external pull-up resistor.
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