isl12032 Intersil Corporation, isl12032 Datasheet - Page 18

• Manufacturer Part Number: isl12032
• Description: Low Power Rtc With Battery Backed Sram And 50/60 Cycle Ac Input And Xtal Back-up
• Manufacturer: Intersil Corporation

BATTERY LEVEL MONITOR TRIP BITS (VB75TP <2:0>)
Three bits selects the second warning (75% of Nominal VBAT)
level for the battery voltage monitor. There are total of 7 levels
that could be selected for the second monitor. Any of the levels
could be selected as the second alarm with no reference as to
nominal VBAT voltage level. See Table 19 for typical values.
AC Register (AC)
This register sets the performance screening for the AC
input.
AC 50/60HZ INPUT SELECT (AC5060)
This bit selects either 50Hz or 60Hz powerline AC clock
input frequency. Setting this bit to “0” selects a 60Hz input
(default). Setting this bit to “1” selects a 50Hz input.
AC ENABLE (ACENB)
This bit will enable/disable the AC clock input. Setting this bit
to “0” will enable the AC clock input (default). Setting this bit
to “1” will disable the AC clock input. When the AC input is
disabled, the crystal oscillator becomes the sole source for
RTC and F
ADDR
13h
VB85Tp2
VB75Tp2
0
0
0
0
1
1
1
0
0
0
0
1
1
1
AC5060 ACENB ACRP1 ACRP0 ACFP1 ACFP0 ACFC1 ACFC0
TABLE 18. VB85T VBAT WARNING LEVELS
TABLE 19. VB75T VBAT WARNING LEVELS
7
OUT
clocking.
VB85Tp1
VB75Tp1
6
TABLE 20. AC REGISTER
0
0
1
1
0
0
1
0
0
1
1
0
0
1
5
18
4
VB85Tp0
VB75Tp0
0
1
0
1
0
1
0
0
1
0
1
0
1
0
3
2
ALARM TRIP
ALARM TRIP
LEVEL (V)
LEVEL (V)
BATTERY
BATTERY
2.125
2.295
2.550
2.805
3.060
4.250
4.675
1.875
2.025
2.250
2.475
2.700
3.750
4.125
1
ISL12032
0
AC RECOVERY PERIOD (ACRP<1:0>)
This bit sets the AC clock input validation recovery period.
After the AC input fails validation (ACFAIL = 1), a predefined
period is used to test the frequency and voltage of the AC
clock input. The range is from 2s to 16s.
AC FAILURE CYCLES (ACFP<1:0>)
These two bits determine how many AC cycles are used for
the AC clock qualification, or to disable the AC clock
qualification. The range is from 1 AC cycle to 12 AC cycles
or disable, and is also dependent on the AC5060 bit setting
(see Table 22). The qualification logic will count the number
of crystal cycles in the chosen AC period, and if the count is
outside the window set by ACFC bits then the ACFAIL signal
is set to “1”.
For example, if 10 cycles are chosen for 50Hz input, then
during those 10 cycles there would need to be exactly 6554
crystal cycles. That number is subtracted from the actual
count during the 10 AC cycles and the absolute value is
compared to the error value set by ACFC. If the error were
10 crystal cycles and ACFC were set to 11b, then the
allowable error would be 20 crystal cycles and the ACFAIL
would be “0”, or qualification has passed. If the actual error
count were 22 cycles then the ACFAIL would be set to “1”,
qualification has failed.
.
AC/CRYSTAL FREQUENCY FAILURE CRITERION
(ACFC<1:0>)
These two bits determine the number of crystal cycles used
for the error budget for the AC qualification (see Table 24).
Two of the choices are for a fixed ppm criterion of 1 or 2
crystal cycles in just one AC cycle (independent of the ACFP
setting). The other choices are for 1 or 2 crystal cycles per
AC cycle, but includes the total number of cycles set by the
ACFP.
Using the example given for the ACFP bits previously
mentioned:
AC5060 = 1 (50Hz)
ACFC = 11b (2 xstal cycles/AC cycle)
AC5060 = 0
CYCLE USED for COUNT
ACRP1
12
1
6
0
0
1
1
(Disabled)
TABLE 21. AC RECOVERY PERIOD
TABLE 22. AC FAILURE CYCLES
AC5060=1
10
1
5
ACRP0
0
1
0
1
ACFP1
0
0
1
1
RECOVERY TIME
December 14, 2007
16s
2s
4s
8s
ACFP0
0
1
0
1
FN6618.0