参数资料
型号: M48T559
厂商: 意法半导体
英文描述: 64 Kbit 8Kb x8 TIMEKEEPER SRAM with ADDRESS/DATA MULTIPLEXED
中文描述: 64千位8KB的x8 SRAM的计时与地址/数据复用
文件页数: 11/18页
文件大小: 147K
代理商: M48T559
11/18
M48T559Y
For more information on calibration, see the Appli-
cation Note AN934 "TIMEKEEPER Calibration".
The IRQ/FT pin is an open drain output which re-
quires a pull-up resistor for proper operation. A
500-10k
resistor is recommended in order to
control the rise time.
SETTING ALARM CLOCK
Registers 1FF5h-1FF2h contain the alarm set-
tings. The alarm can be configured to go off at a
prescribed time on a specific day of the month or
repeat every day, hour, minute, or second. It can
also be programmed to go off while the M48T559Y
is in the battery back-up mode of operation to
serve as a system wake-up call.
RPT1-RPT4 put the alarm in the repeat mode of
operation. Table 11 shows the possible configura-
tions. Codes not listed in the table default to the
once per second mode to quickly alert the user of
an incorrect alarm setting.
Note
: User must transition address (or toggle chip
enable) to see Flag bit change.
When the clock information matches the alarm
clock settings based on the match criteria defined
by RPT1-RPT4, AF (Alarm Flag) is set. If AFE
(Alarm Flag Enable) is also set, the alarm condi-
tion activates the IRQ/FT pin. To disable alarm,
write ’0’ to the Alarm Date registers and RPT1-4.
The alarm flag and the IRQ/FT output are cleared
by a read to the Flags register as shown in Figure
11.
Note:
If an alarm condition occurs while the flags
register address is latched into the address buffer,
the alarm flag will not be set until an address other
than the flags register (1FF0h) is latched into the
address buffer. This will insure that the alarm flag
will not be inadvertently reset while reading the
flag register. To properly check to see if an alarm
condition has occurred while reading the flag reg-
ister, the user is required to latch, read or write to
an alternate address and then re-read the alarm
flag.
The IRQ/FT pin can also be activated in the bat-
tery back-up mode. The IRQ/FT will go low if an
alarm occurs and both ABE (Alarm in Battery
Back-up Mode Enable) and AFE are set. The ABE
and AFE bits are reset during power-up, therefore
an alarm generated during power-up will only set
AF. The user can read the Flag Register at system
boot-up to determine if an alarm was generated
while the M48T559Y was in the deselect mode
during power-up. Figure 12 illustrates the back-up
mode alarm timing.
Figure 10. Interrupt Reset Waveforms
AI01677B
AD0-AD7
ACTIVE FLAG BIT
ADDRESS 1FF0h
R
IRQ/FT
Table 11. Alarm Repeat Mode
RPT4
RPT3
RPT2
RPT1
Alarm Activated
1
1
1
1
Once per Second
1
1
1
0
Once per Minute
1
1
0
0
Once per Hour
1
0
0
0
Once per Day
0
0
0
0
Once per Month
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M48T559YMH1TR 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:64 Kbit 8Kb x8 TIMEKEEPER SRAM with ADDRESS/DATA MULTIPLEXED