MAX8903A Maxim Integrated Products, MAX8903A Datasheet - Page 18

• Manufacturer Part Number: MAX8903A
• Description: 2A 1-Cell Li+ DC-DC Charger for USB* and Adapter Power
• Manufacturer: Maxim Integrated Products

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2A 1-Cell Li+ DC-DC Charger for USB*
and Adapter Power
charging resumes and the charge timer continues from
where it left off. Connecting THM to GND disables the
thermistor monitoring function. Table 4 lists the fault
temperature of different thermistors.
Since the thermistor monitoring circuit employs an
external bias resistor from THM to VL (R
the thermistor is not limited only to 10kΩ (at +25°C).
Figure 6. MAX8903A Charger State Flow Chart
18
TIMER RESUME
______________________________________________________________________________________
THM OK
UOK OR DOK PREVIOUS STATE
TEMPERATURE SUSPEND
CHG = HIGH IMPEDANCE
FLT = HIGH IMPEDANCE
RESET TIMER
V
ANY CHARGING
BATT
I
CHG
STATE
< 2.8V
= 0mA
THM NOT OK
TIMER SUSPEND
RESET TIMER = 0
TB
V
RESET TIMER
, Figure 7),
I
BATT
CHG
UOK AND DOK = HIGH IMPEDANCE
< 2.82V
> I
UOK AND/OR DOK = LOW
UOK AND/OR DOK = LOW
CHG = HIGH IMPEDANCE
CHG = HIGH IMPEDANCE
FLT = HIGH IMPEDANCE
TERM
FLT = HIGH IMPEDANCE
FLT = HIGH IMPEDANCE
FLT = HIGH IMPEDANCE
UOK AND/OR DOK = LOW
CHG = HIGH IMPEDANCE
FLT = HIGH IMPEDANCE
PREQUALIFICATION
UOK AND/OR DOK = 0
I
4.1V < V
CHG
3V < V
FAST-CHARGE
I
CHG
NOT READY
0 < V
CHG = LOW
CHG = LOW
I
I
VBAT = 4.2V
I
CHG
CHG
CHG
≤ I
TOP-OFF
DONE
≤ I
BAT
BAT
CHGMAX
BAT
= 0mA
= 0mA
= I
CHGMAX
TIMER > 15s
< 4.2V
TERM
< 3V
< 4.2V
/10
UOK AND/OR DOK = LOW
CEN = 0
RESET TIMER
Any resistance thermistor can be used as long as the
value is equivalent to the thermistor’s +25°C resistance.
For example, with a 10kΩ at +25°C thermistor, use
10kΩ at R
use 100kΩ .
For a typical 10kΩ (at +25°C) thermistor and a 10kΩ
R
V
RESET TIMER
BATT
TB
I
AND V
AND THERMAL
OR INPUT LIMIT
NOT EXCEEDED;
RESET TIMER
> 3.0V
CHG
resistor, the charger enters a temperature suspend
< I
BAT
TERM
= 4.2V
TB
CEN = HI OR
REMOVE AND RECONNECT
THE INPUT SOURCE(S)
TIMER > t
, and with a 100kΩ at +25°C thermistor,
RESET TIMER
V
BAT
< 4.1V
PREQUAL
TIMER > t
(TIMER SLOWED BY 2x IF
I
PAUSED IF I
CHG
REMOVE AND RECONNECT
THE INPUT SOURCE(S)
< I
UOK AND/OR DOK = LOW
CHG = HIGH IMPEDANCE
TOGGLE CEN OR
CHGMAX
ANY STATE
FSTCHG
CHG
FLT = LOW
I
CHG
FAULT
/2, AND
< I
= 0mA
CHGMAX
/5 WHILE V
BAT
< 4.2V)