ISL12028 Intersil Corporation, ISL12028 Datasheet - Page 25

• Manufacturer Part Number: ISL12028
• Manufacturer: Intersil Corporation

• Mode B - In this mode the selection bits indicate
• Mode C - In this mode the selection bits indicate a low
(X1228
MODE
mode)
switchover to battery backup at V
communications in battery backup. In order to
communicate in battery backup mode, the V
must be less than the V
greater than V
must go to V
as the normal operating mode of the X1228 device
V
battery backup. Operation is actually identical to Mode A
with I
communications. See Figure 29.
DD
A
B
C
D
TABLE 10. I
switchover combined with no communications in
2
C communications down to V
V
SBIB
I
BIT
DD
BAT
0
0
1
1
RESET
BAT
RESET
2
C, LV RESET, AND BATTERY BACKUP OPERATION SUMMARY (SHADED ROW IS SAME AS X1228 OPERATION)
to communicate. This mode is the same
V
(2.2V)
BSW
BIT
TRIP
0
1
0
1
. Also, pullups on the I
V
RESET
BAT
V
V
Standard Mode,
Standard Mode,
25
SWITCHOVER
Legacy Mode,
Legacy Mode,
V
(2.63V)
TRIP
TRIP
voltage AND V
V
V
BAT
VOLTAGE
DD
DD
V
(3.0V)
= 2.2V typ
= 2.2V typ
BAT
< V
< V
DD
FIGURE 29. EXAMPLE RESET OPERATION IN MODE A OR C
(V
DD
BAT
BAT
<V
DD
=V
power, V
BAT
RESET
, and I
DD
2
I
V
2
RESET
C bus pins
C ACTIVE IN
YES, only if
BAT
BACKUP?
tPURST
BATTERY
must be
BAT
>V
, then no
NO
NO
NO
2
C
not connected)
RESET
voltage
ISL12028
READ IN BATTERY
EE PROM WRITE/
I
2
BACKUP?
C Bus Active
YES
NO
NO
NO
• Mode D - In this mode the selection bits indicate
Note that the IRQ/F
backup for all modes. This should be considered if the load
on this pin is powered down, and could draw current from
the PMOS transistor and drain the battery. If that is the case,
the designer should consider the ISL12028 device which has
an open-drain output and avoids excessive current draw in
battery backup.
switchover to battery backup at V
communications in battery backup. This mode is unique in
that there is I
than V
the safest for guaranteeing I
there is a Valid V
RESET
FREQ/IRQ
ACTIVE?
2
or V
C communication as long as V
YES
YES
YES
YES
DD
OUT
BAT
. See Figure 30.
, whichever is greater. This mode is
CMOS output pin is active in battery
Operation of I
V
communications. Battery switchover
at V
Operation of I
backup mode, but only for
V
Bus must have pullups to V
Operation of I
V
communications. Battery switchover
at V
Operation of I
or V
RESET
BAT
RESET
2
TRIP
TRIP
BAT
(Battery backup mode)
C communications only when
>V
, whichever is higher.
, then below that no
, then below that no
DD
.
.
DD
>V
<V
RESET
2
2
2
2
C bus down to V
C bus into battery
C bus down to V
C busdown to V
NOTES
BAT
.
, and no I
DD
is higher
April 17, 2006
BAT
RESET
FN8233.3
.
2
DD
DD
C
=
=