Datasheet

27Maxim Integrated
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
MAX8900A/MAX8900B/MAX8900C
Table 3. 3-Pin Status Output Truth Table
Table 4. 2-Pin Status Output Truth Table
Note: STAT1, STAT2, and STAT3 are open-drain outputs. “0”
indicates that the output device is pulling low. “1” indicates
that the output is high impedance.
Note: STAT1 and STAT2 are open-drain outputs. “0” indicates
that the output device is pulling low. “1” indicates that the out-
put is high impedance.
PVL and AVL Regulator
PVL is a 5V linear regulator that the MAX8900_ uses to
power the gate drivers for its step-down charger. PVL
also charges the BST capacitor. The PVL linear regulator
is on when CEN is low, V
IN
is greater than ~2V, and V
IN
is above V
BAT
by the V
IN2BAT
threshold, otherwise it is
off. Bypass PVL with a 1FF ceramic capacitor to GND.
Powering external loads from PVL is not recommended.
As shown in Figure 3, AVL is a filtered output from the
PVL linear regulator that the MAX8900_ uses to power its
internal analog circuits. The filter consists of an internal
12.5I resistor and the AVL external bypass capacitor
(0.1FF). This filter creates a 127kHz lowpass filter that
cleans the 3.25MHz switching noise from the analog por-
tions of the MAX8900_. Connect a 0.1FF ceramic capaci-
tor from AVL to GND. Powering external loads with AVL
is not recommended.
Charge Status Outputs (3 Pin)
STAT1, STAT2, and STAT3 are open-drain outputs that
indicate the status of the MAX8900B/MAX8900C as
shown in Table 3.
When the status outputs are used to communicate with a
FP, pull them up to the system logic voltage (V
LOGIC
) to
create a signal that has a logic-high and logic-low state that
the FP can easily interpret (Figure 2). Since more than one
status signal may change when the MAX8900B/MAX8900C
changes states, the FP must implement a deglitching
routine for the interpretation of the status signals.
When the status outputs are used to drive LED indicators,
a series resistor should limit the LED current to be less
than 30mA (Figure 1). The STAT1 and STAT2 typical pull-
down resistance is 25I and the absolute maximum rating
is +30V. This +30V rating allows IN to be used to bias
STAT1 and STAT2. The STAT3 typical pulldown resis-
tance is 10I and the absolute maximum rating is +6V.
Charge Status Outputs (2 Pin + > T4)
STAT1 and STAT2 are open-drain outputs that indicate
the status of the MAX8900A as shown in Table 4.
When the status outputs are used to communicate with a
FP, pull them up to the system logic voltage (V
LOGIC
) to
create a signal that has a logic-high and logic-low state
that the FP can easily interpret (Figure 2). Since more
than one status signal may change when the MAX8900A
changes states, the FP must implement a deglitching
routine for the interpretation of the status signals.
When the status outputs are used to drive LED indica-
tors, a series resistor should limit the LED current to
be less than 30mA (Figure 1). Note that the STAT1 and
STAT2 typical pulldown resistance is 25I and the abso-
lute maximum rating is +30V. This +30V rating allows IN
to be used to bias STAT1 and STAT2.
STAT3 pulls low when the battery temperature moni-
tor detects that the battery temperature is greater than
the T4 threshold, otherwise, STAT3 is high impedance.
Some systems may want to reduce the battery loading
when STAT3 pulls low to prevent the battery from getting
excessively hot.
STAT1 STAT2 STAT3 INDICATION
0 0 0 Battery cold (THM < T1)
0 0 1 V
IN
> V
OVLO
0 1 0
Charging (dead-battery state or
dead battery + prequalification
state or prequalification state or
fast-charge state)
0 1 1 Battery hot (THM >T4)
1 0 0 Done state
1 0 1
Undefined. This
state does not occur.
1 1 0 Timer fault
1 1 1
V
IN
< V
UVLO
or CEN = 1 or
V
IN
< (V
BAT
+ V
IN2BAT
) or
thermal shutdown
STAT1 STAT2 INDICATION
0 0
Undefined. This does not occur
when the MAX8900_ is powered.
0 1
Charging (dead-battery state or
dead battery + prequalification state
or prequalification state or fast-
charge state)
1 0
Timer fault or V
IN
> V
OVLO
or bat-
tery cold (THM < T1) or battery hot
(THM > T4)
1 1
Done state or CEN = 1 or V
IN
<
V
UVLO
or V
IN
< (V
BAT
+ V
IN2BAT
) or
thermal shutdown