12022IBZ Ver la hoja de datos (PDF) - Renesas Electronics
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12022IBZ
Renesas Electronics
12022IBZ Datasheet PDF : 29 Pages
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ISL12022
Typical Performance Curves Temperature is +25°C unless otherwise specified. (Continued)
110
100
90
80
70
60
50
40-40
VDD = 5.5V
VDD = 3.3V
VBAT = 2.7V
-20
0
20
40
60
80
TEMPERATURE (°C)
110
100
90
80
VBAT = 5.5V
70
60
VBAT = 3.0V
50
VBAT = 1.8V
40
30
20 -40
-20
0
20
40
60
80
TEMPERATURE (°C)
FIGURE 9. IDD WITH TSE = 1 vs TEMPERATURE
FIGURE 10. IBAT with TSE = 1, BTSE = 1 vs TEMPERATURE
General Description
The ISL12022 device is a low power real time clock (RTCs) with
embedded temperature sensors. It contains crystal frequency
compensation circuitry over the operating temperature range,
clock/calendar, power fail and low battery monitors, brownout
indicator, 1 periodic or polled alarm, intelligent battery-backup
switching and 128 Bytes of battery-backed user SRAM.
The oscillator uses an external, low cost 32.768kHz crystal. The
real time clock tracks time with separate registers for hours,
minutes and seconds. The device has calendar registers for date,
month, year and day of the week. The calendar is accurate
through 2099, with automatic leap year correction. In addition,
the ISL12022 can be programmed for automatic Daylight
Savings Time (DST) adjustment by entering local DST
information.
The ISL12022’s alarm can be set to any clock/calendar value for
a match, for example, every minute, every Tuesday or at 5:23 AM
on March 21. The alarm status is available by checking the
Status Register, or the device can be configured to provide a
hardware interrupt via the IRQ/FOUT pin. There is a repeat mode
for the alarm allowing a periodic interrupt every minute, every
hour, every day, etc.
The device also offers a backup power input pin. This VBAT pin
allows the device to be backed up by battery or super capacitor
with automatic switchover from VDD to VBAT. The ISL12022
device is specified for VDD = 2.7V to 5.5V and the clock/calendar
portion of the device remains fully operational in battery-backup
mode down to 1.8V (Standby Mode). The VBAT level is monitored
and reported against preselected levels. The first report is
registered when the VBAT level falls below 85% of nominal level,
the second level is set for 75%. Battery levels are stored in
PWR_VBAT registers.
The ISL12022 offers a “Brownout†alarm once the VDD falls
below a pre-selected trip level. This allows system Micro to save
vital information to memory before complete power loss. There
are six VDD levels that could be selected for initiation of the
Brownout alarm.
Pin Descriptions
X1, X2
The X1 and X2 pins are the input and output, respectively, of an
inverting amplifier. An external 32.768kHz quartz crystal is used
with the device to supply a timebase for the real time clock.
Internal compensation circuitry with internal temperature sensor
provides frequency corrections for selected popular crystals to
±5ppm over the operating temperature range from -40°C to
+85°C. (See “Application Section†on page 25 for recommended
crystal). The ISL12022 allows the user to input via I2C serial bus
the temperature variation profile of an individual crystal. The
oscillator compensation network can also be used to calibrate
the initial crystal timing accuracy to less than 1ppm error at
room temperature. The device can also be driven directly from a
32.768kHz source at pin X1.
X1
X2
FIGURE 11. RECOMMENDED CRYSTAL CONNECTION
VBAT
This input provides a backup supply voltage to the device. VBAT
supplies power to the device in the event that the VDD supply
fails. Device power will automatically switch to the VBAT input
when VDD drops below the switchover trip level (VTRIP). This pin
can be connected to a battery, a super capacitor or tied to ground
if not used.
IRQ/FOUT (Interrupt Output/Frequency
Output)
This dual function pin can be used as an interrupt or frequency
output pin. The IRQ/FOUT mode is selected via the frequency out
control bits of the control/status register. It is an open drain
output.
FN6659 Rev 3.00
Nov 22, 2011
Page 9 of 29
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