M48TMH1 STMICROELECTRONICS [STMicroelectronics], M48TMH1 Datasheet - Page 8

• Manufacturer Part Number: M48TMH1
• Description: 5V PC REAL TIME CLOCK
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M48T86
Table 7. Power Down/Up Trip Points DC Characteristics
(T
Note: 1. All voltages referenced to V
Table 8. Power Down/Up Mode AC Characteristics
(TA = 0 to 70°C)
Note: 1. V
Figure 7. Power Down/Up Mode AC Waveforms
INTERRUPTS
The RTC plus RAM includes three separate, fully
automatic sources of interrupt (alarm, periodic, up-
date-in-progress) available to a processor. The
alarm interrupt can be programmed to occur at
rates from once per second to once per day. The
periodic interrupt can be selected from rates of
500ms to 122µs. The update-ended interrupt can
be used to indicate that an update cycle has com-
pleted.
The processor program can select which inter-
rupts, if any, are going to be used. Three bits in
8/23
A
Symbol
Symbol
t
= 0 to 70 °C)
V
DR
t
t
V
2. At 25°C.
F
REC
PFD
t
SO
R
(1)
(2)
CC
V CC
4.5V
V PFD
V SO
E
fall time of less than t
Power-fail Deselect Voltage
Battery Back-up Switchover Voltage
Expected Data Retention Time
V
V
V
CC
CC
PFD
Fall Time
Rise Time
to E High
F
SS
may result in deselection/write protection not occurring until 200µs after V
Parameter
.
Parameter
tF
Register B enable the interrupts. Writing a logic "1"
to an interrupt-enable bit (Register B; Bit 6 = PIE;
Bit 5 = AIE; Bit 4 = UIE) permits an interrupt to be
initialized when the event occurs. A zero in an in-
terrupt-enable bit prohibits the IRQ pin from being
asserted from that interrupt condition. If an inter-
rupt flag is already set when an interrupt is en-
abled, IRQ is immediately set at an active level,
although the interrupt initiating the event may have
occurred much earlier. As a result, there are cases
where the program should clear such earlier initi-
ated interrupts before first enabling new interrupts.
(1)
Min
4.0
10
Min
300
100
20
Typ
3.0
Max
200
tR
CC
Max
4.35
passes V
tREC
AI01646
PFD
Unit
YEARS
ms
µs
µs
.
Unit
V
V