ISL12032 Datasheet, PDF (15/26 Pages) Intersil Corporation – Low Power RTC with Battery Backed SRAM and 50/60 Cycle AC Input and Xtal Back-up

ISL12032
Event Count (EVTCNT)
TABLE 5. EVENT COUNTER REGISTER (EVTCNT)
ADDR 7
6
5
4
3
2
1
0
0Bh EVC7 EVC6 EVC5 EVC4 EVC3 EVC2 EVC1 EVC0
The EVTCNT register increments automatically each time an
event occurs. The register is set to 00h on initial power-up.
The maximum count is 255, and will stay at that value until
set to zero via an I²C write.
Performing a write of 00h to this register will clear the
contents of this register and all levels of the TSEVT section.
A clear to this register should be done with care. Write event
index register zero only selects first event time stamp. Write
event count EVNTCNT zero will both clear event counter
and all time stamps.
Control Registers
Addresses [0Ch to 14h]
The control registers (INT, FO, EVIC, EVIX, TRICK,
PWRVDD, PWRBAT, AC, and FTR) contain all the bits
necessary to control the parametric functions on the
ISL12032.
Interrupt Control Register (INT)
TABLE 6. INTERRUPT CONTROL REGISTER (INT)
ADDR 7
6
5
4 32 1
0
0Ch ARST WRTC IM X X X ALE1 ALE0
AUTOMATIC RESET BIT (ARST)
This bit enables/disables the automatic reset of the ALM0,
ALM1, LVDD, LBAT85, and LBAT75 status bits only. When
ARST bit is set to “1”, these status bits are reset to “0” after a
valid read of the SRDC Register (with a valid STOP
condition). When the ARST is cleared to “0”, the user must
manually reset the ALM0, ALM1, LVDD, LBAT85, and
LBAT75 bits.
WRITE RTC ENABLE BIT (WRTC)
The WRTC bit enables or disables write capability into the
RTC Register section. The factory default setting of this bit is
“0”. Upon initialization or power-up, the WRTC must be set
to “1” to enable the RTC. Upon the completion of a valid
write (STOP), the RTC starts counting. The RTC internal
1Hz signal is synchronized to the STOP condition during a
valid write cycle. This bit will remain set until reset to “0” or a
complete power-down occurs (V_DD = VBAT = 0.0V)
ALARM INTERRUPT MODE BIT (IM)
This bit enables/disables the interrupt mode of the alarm
function. When the IM bit is set to “1”, the alarms will operate
in the interrupt mode, where an active low pulse width of
250ms will appear at the IRQ pin when the RTC is triggered
by either alarm as defined by the Alarm0 section (1Dh to
22h) or the Alarm1 section (23h to 28h). When the IM bit is
cleared to “0”, the alarm will operate in standard mode,
where the IRQ pin will be set LOW until both the
ALM0/ALM1 status bits are cleared to “0”.
ALARM 1 (ALE 1)
This bit enables the Alarm1 function. When ALE1 = “1”, a
match of the RTC section with the Alarm1 section will result
is setting the ALM1 status bit to “1” and the IRQ output LOW.
When set to “0”, the Alarm1 function is disabled.
ALARM 0 (ALE 0)
This bit enables the Alarm0 function. When ALE0 = 1, a
match of the RTC section with the Alarm1 section will result
is setting the ALM0 status bit to “1” and the IRQ output LOW.
When set to “0”, the Alarm0 function is disabled.
Frequency Out Register (FO)
TABLE 7. FREQUENCY OUT REGISTER (FO)
ADDR 7
6
5
4
3210
0Dh X
X
X FOBATB X FO2 FO1 FO0
FREQUENCY OUTPUT AND INTERRUPT BIT (FOBATB)
This bit enables/disables F_OUT during battery backup mode
(i.e. VBAT power source active). When the FOBATB is set to
“1” the F_OUT pin is disabled during battery backup mode. When
the FOBATB is cleared to “0”, the F_OUT pin is enabled during
battery backup mode (default). Note that F_OUT is a CMOS
output and needs no pull-up resistor. Note also that battery
current drain will be higher with F_OUT enabled in battery
backup mode.
FREQUENCY OUT CONTROL BITS (FO <2:0>)
These bits enable/disable the frequency output function and
select the output frequency at the F_OUT pin. See Table 8 for
frequency selection. Note that frequencies from 4096Hz to
32768Hz are derived from the Crystal Oscillator, and the 1.0,
10, and 50/60Hz frequencies are derived from the AC clock
input. The exception to this is when the AC input qualification
has failed, and the crystal oscillator is used for the 1.0Hz
F_OUT.
TABLE 8. FREQUENCY SELECTION OF F_OUT PIN
FREQUENCY,
F_OUT
UNITS FO2
FO1
FO0
32768
Hz
0
0
0
16372
Hz
0
0
1
8192
Hz
0
1
0
4096
Hz
0
1
1
50/60
Hz
1
0
0
1
Hz
1
0
1
Low
Hz
1
1
0
High
Hz
1
1
1
15
FN6618.2
April 16, 2009