MAX8900A MAXIM [Maxim Integrated Products], MAX8900A Datasheet - Page 22

• Manufacturer Part Number: MAX8900A
• Manufacturer: MAXIM [Maxim Integrated Products]

When CEN is high or the input voltage is out of range, the
MAX8900_ disables the charger. To exit this state, CEN must
be low and the input voltage must be within its valid range.
When a deeply discharged battery is inserted with a
voltage of less than V
switching charger and linearly charges with I
V
the prequalification timer and transitions to the dead
battery + prequalification state. This state prevents the
MAX8900_ from dissipating excessive power in the event
of a shorted battery. The dead-battery linear charger
remains on except when in the charger disabled state,
timer fault state, thermal shutdown, and V
The dead battery + prequalification state occur when
the battery voltage is greater than V
V
and the switching charger are on and delivering current
to the battery. The total battery current is I
the MAX8900_ remains in this state for longer than t
then the MAX8900_ transitions to the timer fault state.
A normal battery typically stays in this state for several
minutes or less and when the battery voltage rises above
V
state. The dead-battery linear charger remains on except
when in the charger disabled state, timer fault state, ther-
mal shutdown, and V
The prequalification state occurs when the battery volt-
age is greater than V
In this state, the linear dead-battery charger is turned
off and only the switching charger is on and delivering
current to the battery. The total battery current is I
the MAX8900_ remains in this state for longer than t
then the MAX8900_ transitions to the timer fault state. A
normal battery typically stays in the prequalification state
for several minutes or less and when the battery voltage
rises above V
fast-charge constant current state.
As shown in Figure 10, the prequalification current and
done threshold is set to 50% of programmed value when
T1 < THM < T2, and 100% of programmed value when
T2 < THM < T4.
The fast-charge constant current state occurs when the
battery voltage is greater than V
1.2A Switch-Mode Li+ Chargers with ±22V Input
Rating and JEITA Battery Temperature Monitoring
22
BAT
DBAT
DBAT
increases beyond V
. In this state, both the linear dead-battery charger
, the MAX8900_ transitions to the prequalification
PQUTH
Dead Battery + Prequalification State
Fast-Charge Constant Current State
BAT
DBAT
PQLTH
, the MAX8900_ transitions to the
> V
PQLTH,
and less than V
, the MAX8900_ disables the
DBAT
Charger Disabled State
Prequalification State
PQUTH
.
the MAX8900_ clears
PQLTH
Dead-Battery State
BAT
and less than
DBAT
PQUTH
and less than
DBAT
> V
+ I
.
. Once
DBAT
PQ
PQ
PQ
PQ
. If
. If
.
,
,
V
delivering current to the battery. The total battery current
is I
charge constant voltage state for longer than t
the MAX8900_ transitions to the timer fault state. When
the battery voltage rises to V
transitions to the fast-charge constant voltage state. As
shown in Figure 10, the fast-charge constant current is
set to 50% of programmed value when T1 < THM < T2,
and 100% of programmed value when T2 < THM < T4.
The MAX8900_ dissipates the most power in the fast-
charge constant current state. This power dissipation
causes the internal die temperature to rise. If the die tem-
perature exceeds T
Foldback section for more detail.
If there is low input voltage headroom (V
I
Figure 13 for more detail.
The fast-charge constant voltage state occurs when the
battery voltage is at the V
is greater than I
on and delivering current to the battery. The MAX8900_
maintains V
detect when the battery consumes less than the I
rent. When the charge current decreases below the I
threshold, the MAX8900_ transitions to the top-off state.
If the MAX8900_ remains in the fast-charge constant
current state and this state for longer than t
MAX8900_ transitions to the timer fault state. Please note
when the battery temperature is between T3 and T4 the
BAT regulation voltage is reduced to 4.075V.
The MAX8900_ offers an adjustable done current thresh-
old (I
top-off current threshold is Q1mA when it is set for 10mA.
This accurate threshold allows the maximum amount of
charge to be stored in the battery before the MAX8900_
transitions into done state.
The top-off state occurs when the battery voltage is
at V
I
ers current to the battery. The MAX8900_ maintains
V
the MAX8900_ transitions to the done state. If the charg-
ing current increases to I
then the charger re-enters the fast-charge constant volt-
age state.
FC
DN
BATREG
BATREG
FC
. In this state, the switching charger is on and deliv-
decreases due to the impedance from IN to BAT. See
BATREG
. If the MAX8900_ remains in this state and the fast-
DN
) from 10mA to 200mA. The accuracy of the
. In this state, the switching charger is on and
for a specified time (t
BATREG
and the battery current decreases below
DN
Fast-Charge Constant Voltage State
. In this state, the switching charger is
REG
and monitors the charge current to
, I
BATREG
FC
DN
is reduced. See the Thermal
+ 1mA before t
BATREG
TO
and the charge current
). When t
, the MAX8900_
IN
Top-Off State
- V
FC
TO
TO
BAT
, then the
FC
expires,
expires,
DN
), then
, then
cur-
DN