MAX8845Y

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

Industry's First 30V-Rated, Single-Input, 1-Cell Li+ Battery Chargers with Overvoltage-Protected Output

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Overview

CCCV, Thermally Regulated Linear 1-Cell Li+ Battery Charger
No External MOSFET, Reverse Blocking Diode, or Current-Sense Resistor
Programmable Fast-Charge Currents (1A_RMS max)
Programmable Top-Off Current Threshold (MIN)
Input Overvoltage Protected 4.7V Output (MAX8845Z/MAX8845Y/MAX8845W) or 4.85V (MAX8845X) (SAFEOUT)
Proprietary Die Temperature Regulation Control (+115°C)
4.25V (4.4V for MAX8845W only) to 28V Input Voltage Range with Input Overvoltage Protection Above +7.5V (+8.0V for MAX8845X only)
Low-Dropout Voltage (300mV at 500mA)
Input Power-Source Detection Output (Active-Low POK), Charge Status Output (Active-Low CHG), Charge-Enable Input (Active-Low EN)
Output for Autobooting (ABO—MAX8845Z, Active-Low ABO—MAX8845Y/MAX8845X/MAX8845W)
Tiny, 3mm x 3mm 12-Pin Thin QFN Package, 0.8mm Height (max)

The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W are intelligent, stand-alone constant-current, constant-voltage (CCCV), thermally regulated linear chargers designed for charging a single-cell lithium-ion (Li+) battery. The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W integrate a current-sense circuit, MOSFET pass element, thermal-regulation circuitry, and eliminate the external reverse-blocking Schottky diode to create the simplest and smallest charging solutions for handheld equipment.

The ICs control the charging sequence from the pre-qualification state through constant current fast-charge, top-off charge, and full-charge indication. Proprietary thermal-regulation circuitry limits the die temperature during fast-charging or when the ICs are exposed to high ambient temperatures, allowing maximum charging current without damaging the ICs.

The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W achieve high flexibility by providing adjustable fast-charge currents (SETI) and an adjustable top-off current threshold (MIN) through external resistors. The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W feature a booting assistant circuit that distinguishes input sources and battery connection and provides an enable signal (ABO—MAX8845Z and active-low ABO—MAX8845Y/MAX8845X/MAX8845W) for system booting.

The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W also integrate an overvoltage-protected output (SAFEOUT) for low voltage-rated USB or charger inputs in system, and a battery-pack detection circuit (DETBAT) that disables the charger when the battery pack is absent. Other features include an active-low control input (active-low EN), an active-low input power source detection output (active-low POK), and a fully charged top-off threshold detection output (active-low CHG).

The MAX8845Z/MAX8845Y/MAX8845X/MAX8845W accept an input supply range from 4.25V (4.4V for MAX8845W only) to 28V, but disable charging if the supply voltage exceeds +7.5V (+8.0V for MAX8845X only) to protect against unqualified or faulty AC adapters. The ICs operate over the extended temperature range (-40°C to +85°C) and are available in a compact 12-pin, thermally enhanced thin QFN, 3mm x 3mm package (0.8mm max height).

Applications

Bluetooth® Equipment
Cellular and Cordless Phones
Charging Cradles and Docks
Digital Still Cameras
MP3 Players
Smart Phones and PDAs
USB Appliances

Documentation

Data Sheet 1

MAX8845W-MAX8845Z: 28V Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output Data Sheet (Rev.1) 11/24/2009

Reliability Data 1

MAX8845Y Reliability Data 01/12/2023

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Evaluation Kits

Evaluation Kit for the MAX8845Z and MAX8845Y

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Features and Benefits

CCCV, Thermally Regulated Linear Single-Cell Li+ Battery Charger
No External MOSFET, Reverse-Blocking Diode, or Current-Sense Resistor
Programmable Fast-Charge Currents (1A_RMS max)
Programmable Top-Off Current Threshold
Input Overvoltage-Protected 4.7V Output (SAFEOUT) from DC
Proprietary Die Temperature Regulation Control (+115°C)
4.25V to 28V Input-Voltage Range with Input Overvoltage Protection Above +7.5V
Low-Dropout Voltage (300mV at 500mA)
Input Power-Source Detection Output (Active-Low POK), Charge Status Output (Active-Low CHG), and Charge-Enable Input (Active-Low EN)
Output for Autobooting (MAX8845Z = ABO, MAX8845Y = Active-Low ABO)
Lead(Pb)-Free and RoHS Compliant

Product Details

The MAX8845Z evaluation kit (EV kit) is a fully assembled and tested PCB for evaluating the MAX8845Z/MAX8845Y 28V linear Li+ battery chargers.

The MAX8845Z EV kit features an overvoltage-protected LDO output (SAFEOUT) for low-voltage-rated USB or charger inputs in the system, and a battery pack detection circuit (DETBAT) that disables the IC when the battery pack is absent. The IC disables charging if the input sources exceed 7.5V to protect against unqualified or faulty AC adapters. The MAX8845Z EV kit also features an adjustable fast-charge current set by an external resistor (R1) and an adjustable top-off current threshold set by an external resistor (R2).

Other features include an active-low control input (EN) and an active-low input power source detection output (POK). The IC also contains a booting assistant circuit that distinguishes input sources and battery connection, and provides an output signal (MAX8845Z = ABO, MAX8845Y = active-low ABO) for system booting.

To evaluate the MAX8845Y version, order the MAX8845YETC+ along with the MAX8845ZEVKIT+ and see the Evaluating the MAX8845Y section.