Rainbow-electronics MAX8903A Bedienungsanleitung PDF herunterladen (Seite 18)

MAX8903A

2A 1-Cell Li+ DC-DC Charger for USB*

and Adapter Power

18 ______________________________________________________________________________________

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

, Figure 7),

the thermistor is not limited only to 10kΩ (at +25°C).

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

, and with a 100kΩ at +25°C thermistor,

use 100kΩ .

For a typical 10kΩ (at +25°C) thermistor and a 10kΩ

resistor, the charger enters a temperature suspend

FAULT

UOK AND/OR DOK = LOW

CHG = HIGH IMPEDANCE

FLT = LOW

CHG

= 0mA

PREQUALIFICATION

UOK AND/OR DOK = LOW

CHG = LOW

FLT = HIGH IMPEDANCE

0 < V

BAT

< 3V

CHG

≤ I

CHGMAX

/10

DONE

UOK AND/OR DOK = 0

CHG = HIGH IMPEDANCE

FLT = HIGH IMPEDANCE

4.1V < V

BAT

< 4.2V

CHG

= 0mA

FAST-CHARGE

UOK AND/OR DOK = LOW

CHG = LOW

FLT = HIGH IMPEDANCE

3V < V

BAT

< 4.2V

CHG

≤ I

CHGMAX

NOT READY

UOK AND DOK = HIGH IMPEDANCE

CHG = HIGH IMPEDANCE

FLT = HIGH IMPEDANCE

CHG

= 0mA

TIMER > t

PREQUAL

BATT

> 3.0V

RESET TIMER

BATT

< 2.82V

RESET TIMER = 0

CHG

< I

TERM

AND V

BAT

= 4.2V

AND THERMAL

OR INPUT LIMIT

NOT EXCEEDED;

RESET TIMER

CHG

> I

TERM

RESET TIMER

BAT

< 4.1V

RESET TIMER

TIMER > 15s

UOK AND/OR DOK = LOW

CEN = 0

RESET TIMER

CEN = HI OR

REMOVE AND RECONNECT

THE INPUT SOURCE(S)

ANY STATE

TOGGLE CEN OR

REMOVE AND RECONNECT

THE INPUT SOURCE(S)

TIMER > t

FSTCHG

(TIMER SLOWED BY 2x IF

CHG

< I

CHGMAX

/2, AND

PAUSED IF I

CHG

< I

CHGMAX

/5 WHILE V

BAT

< 4.2V)

TOP-OFF

UOK AND/OR DOK = LOW

CHG = HIGH IMPEDANCE

FLT = HIGH IMPEDANCE

VBAT = 4.2V

CHG

= I

TERM

TEMPERATURE SUSPEND

CHG

= 0mA

UOK OR DOK PREVIOUS STATE

CHG = HIGH IMPEDANCE

FLT = HIGH IMPEDANCE

ANY CHARGING

STATE

THM NOT OK

TIMER SUSPEND

THM OK

TIMER RESUME

BATT

< 2.8V

RESET TIMER

Figure 6. MAX8903A Charger State Flow Chart

1 2 ... 13 14 15 16 17 18 19 20

MAX8903A 1

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