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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

Product Details

Key Features

Simplified Block Diagram

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Key Features

  • CCCV, Thermally Regulated Linear 1-Cell Li+ Battery Charger
  • No External MOSFET, Reverse Blocking Diode, or Current-Sense Resistor
  • Programmable Fast-Charge Currents (1ARMS 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)

Applications/Uses

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

Description

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).

Simplified Block Diagram

MAX8845W, MAX8845X, MAX8845Y, MAX8845Z: Typical Operating Circuit MAX8845W, MAX8845X, MAX8845Y, MAX8845Z: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .