Datasheet

To achieve rated performance, the V
CC
input should be
connected to both V
CCI
pins (pins 15 and 16). As well, the
switched output should be connected to both V
CCO
pins
(pins 12 and 13).
Power Fail
The power-fail (PF) output is high for V
CCI
greater than
1.26 x V
BATT
(V
TP
), indicating a valid V
CCI
voltage.
Battery Fail
If V
CCI
is at or above the voltage trip threshold (VTP) and
the backup battery is greater than 2V, the battery-fail (BF)
output will be held high, indicating a charged battery. If the
backup battery drops below 2V or V
CCI
falls below V
TP
,
BF will be driven low.
BAT Output
During normal operation, the BAT output stays at the bat-
tery voltage, regardless of the V
CCI
level. This provides
1mA battery current.
RESET (Digitally Controlled
Battery Disconnect)
To prevent battery discharge during shipping, the backup
battery can be disconnected from V
CCO
to BAT.
This disconnect feature is activated by pulsing the reset
(RST) input high for a minimum of 50ns with V
CCI
greater
than V
TP
(Figure 4). When primary power is removed,
the V
CCO
and BAT outputs will go high impedance. The
next time primary power is applied with V
CCI
greater than
1.26 x V
BATT (VTP)
, normal operation resumes. Note that
when the MAX1259 is first powered up, V
CCI
must be
brought above 1.26 x V
BATT
. This resets an internal flip-
flop, ensuring that the part is in normal V
CC
mode and not
in shipping mode.
Applications Information
If a protection diode is placed in series with the backup
battery, pin 2 must be bypassed with at least a 0.01μF
capacitor to ground.
Figure 4. Reset Timing
+5V
V
CCI
V
CCO
RST
0V
+5V
+3V
0V
+3V
0V
V
IH
V
IL
BAT
50ns MIN
HIGH IMPEDANCE
HIGH IMPEDANCE
MAX1259 Battery Manager
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