MAX8845Z Просмотр технического описания (PDF) - Maxim Integrated

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MAX8845Z

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

MAX8845X

MAX8845W

VL

REGULATOR

VL

UVLO

VL

REF

VREF

REFOK

GND

EP

POK

BATT

LOGIC

200kΩ

200kΩ

SAFEOUT

BATT

4.2V Li+

(4.35V FOR

MAX8845W ONLY)

DETBAT

VI/O

CHG

POK

ABO (MAX8845Z ONLY)

ABI

ABO (MAX8845Y/MAX8845X/MAX8845W)

EN

Figure 1. MAX8845Z/MAX8845Y/MAX8845X/MAX8845W Functional Diagram

Detailed Description

The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W

chargers use voltage, current, and thermal-control

loops to charge a single Li+ cell and protect the battery

(Figure 1). When a Li+ battery with a cell voltage below

2.5V is inserted, the MAX8845Z/MAX8845Y/MAX8845X/

MAX8845W chargers enter a prequalification stage

where it precharges that cell with 10% of the user-pro-

grammed fast-charge current (Figure 2). The CHG indi-

cator is driven low to indicate entry into the prequalifi-

cation 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 programmed

through a resistor from SETI to GND. As the battery

voltage approaches 4.2V, the charging current is

reduced. If the battery current drops to less than the

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