MAX8845ZETC(2009_03) Просмотр технического описания (PDF) - Maxim Integrated

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MAX8845ZETC
(Rev.:2009_03)

28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage Protected Output

Maxim Integrated 

28V Linear Li+ Battery Chargers with Battery

Detection and Overvoltage Protected Output

LINEAR

REGULATOR

WITH OVP

IN

SETI

MIN

IN

OUTPUT DRIVER,

CURRENT SENSE,

AND LOGIC

VREF

IMINREF

+115°C

TEMPERATURE

SENSOR

VREF

VIN

OVLO

BATT

DETBAT

MAX8845Z

MAX8845Y

VL

REGULATOR

VL

UVLO

VL

REF

VREF

REFOK

GND

EP

POK

BATT

LOGIC

200kΩ

200kΩ

SAFEOUT

BATT

4.2V

Li+

DETBAT

VI/O

CHG

POK

ABO (MAX8845Z ONLY)

ABI

ABO (MAX8845Y ONLY)

EN

Figure 1. MAX8845Z/MAX8845Y Functional Diagram

Detailed Description

The MAX8845Z/MAX8845Y chargers use voltage, cur-

rent, and thermal-control loops to charge a single Li+

cell and protect the battery (Figure 1). When a Li+ bat-

tery with a cell voltage below 2.5V is inserted, the

MAX8845Z/MAX8845Y chargers enter a prequalifica-

tion stage where it precharges that cell with 10% of the

user-programmed fast-charge current (Figure 2). The

CHG indicator is driven low to indicate entry into the

prequalification state. When the battery voltage

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

fast-charge stage. The fast-charge current level is pro-

grammed through a resistor from SETI to GND. As the

battery voltage approaches 4.2V, the charging current

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