1A Linear Li+ Battery Chargers with Integrated Pass

FET and Thermal Regulation in 2mm x 2mm TDFN

6

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Detailed Description

The MAX8808X/MAX8808Y/MAX8808Z chargers use

voltage, current, and thermal-control loops to charge a

a Li+ battery with a cell voltage below 2.5V is inserted,

the MAX8808X charger enters the prequalification

stage where it precharges that cell with 10% of the

CHG indicator output is driven low to indicate entry into

the prequalification state. When battery voltage

exceeds 2.5V, the charger soft-starts as it enters the

fast-charge stage. In the MAX8808X/MAX8808Y/

MAX8808Z, the fast-charge current level is pro-

grammed through a resistor from ISET to GND. As the

battery voltage approaches 4.2V, the charging current

is reduced. If the battery current drops to less than

10% of the fast-charging current, the CHG indicator

goes high impedance, signaling that the battery is fully

charged. The ICs then enter a constant voltage-regula-

tion mode to maintain the battery at full charge.

MAX8808X

MAX8808Y

MAX8808Z

IN

ISET

VL

CHG

EN (MAX8808Y)

GND

BATT

1

µF

ACOK

TEMP

SENSOR

OUTPUT DRIVER, CURRENT

SENSE, AND LOGIC

VL

REF OK

0.47

µF

100k

Ω

2.8k

Ω

1

µF

4.25V TO 15V

OVP

UVLO

LOGIC

IN

ON

+115

°C

BATT

IN

IN

REF

N

100k

Ω

EN

(MAX8808X/

MAX8808Z)

200k

Ω