ISL12027_10 Datasheet, PDF (25/28 Pages) Intersil Corporation – Real Time Clock/Calendar with EEPROM

ISL12027, ISL12027A
.
TABLE 10. I²C, LV RESET, AND BATTERY BACKUP OPERATION SUMMARY (Shaded Row is same as X12028 operation)
MODE
SBIB
BIT
BSW
BIT
V_BAT
I²C ACTIVE IN
SWITCHOVER BATTERY
VOLTAGE
BACKUP?
EE PROM WRITE/
READ IN BATTERY
BACKUP?
FREQ/IRQ
ACTIVE?
NOTES
A
0
0 Standard Mode,
NO
V_TRIP = 2.2V
typ
Default for
ISL12027A
NO
N/A
Operation of I²C bus down to V_DD =V_RESET,
then below that no communications. Battery
switchover at V_TRIP.
B
0
(X12028
mode)
C
1
D
1
1 Legacy Mode, YES, only if
V_DD < V_BAT V_BAT > V_RESET
Default for
ISL12027
0 Standard Mode,
NO
V_TRIP = 2.2V
typ
1 Legacy Mode,
NO
V_DD < V_BAT
YES
NO
NO
Yes
YES
YES
Operation of I²C bus into battery backup
mode, but only for
V_BAT > V_DD > V_RESET.
Bus must have pull-ups to V_BAT. No
non-volatile writes with V_BAT > V_DD
Operation of I²C bus down to V_DD = V_RESET,
then below that no communications. Battery
switchover at V_TRIP.
Operation of I²C busdown to V_RESET or
V_BAT, whichever is higher.
.
V_DD
V_BAT (3.0V)
V_RESET (2.63V)
V_TRIP
(2.2V)
tPURST
RESET
I_BAT
I²C Bus Active
(VDD POWER, V_BAT NOT CONNECTED)
(BATTERY BACKUP MODE)
FIGURE 29. EXAMPLE RESET OPERATION IN MODE A OR C
V_DD
V_BAT (3.0V)
V_RESET (2.63V)
V_TRIP
(2.2V)
tPURST
RESET
I_BAT
25
I²C BUS ACTIVE
FIGURE 30. RESET OPERATION IN MODE D
(BATTERY BACKUP MODE)
FN8232.8
August 12, 2010