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SMBus Level 2 Battery Charger with Remote Sense

Low-Cost SMBus Charger with Integrated Dual n-Channel FET Drivers Deliver Up to 8A Charge Current

Product Details

The MAX8731A is an SMBus™ programmable multi-chemistry battery charger. The MAX8731A uses a minimal command set to easily program the charge voltage, charge current, and adapter current limit.

The MAX8731A charges one to four Li+ series cells and delivers up to 8A charge current. The MAX8731A drives n-channel MOSFETs for improved efficiency and reduced cost. Low-offset current-sense amplifiers provide high accuracy with 10mΩ sense resistors.

The MAX8731A current-sense amplifiers provide high accuracy (3% at 3.5A) and also provide fast cycle-by-cycle current-mode control to protect against battery short circuit and system load transients.

The charger employs dual remote sense, which reduces charge time by measuring the feedback voltage directly at the battery, improving accuracy of initial transition into constant-voltage mode. The MAX8731A provides 0.5% battery voltage accuracy directly at the battery terminal.

The MAX8731A provides a digital output that indicates the presence of the AC adapter, as well as an analog output that indicates the adapter current within 4% accuracy.

The MAX8731A is available in a small 5mm x 5mm, 28-pin, thin (0.8mm) QFN package. An evaluation kit is available to reduce design time. The MAX8731A is available in a lead-free package.

Key Features

  • 0.5% Battery Voltage Accuracy
  • 3% Input Current-Limit Accuracy
  • 3% Charge-Current Accuracy
  • SMBus 2-Wire Serial Interface
  • Cycle-by-Cycle Current Limit
    • Battery Short-Circuit Protection
    • Fast Response for Pulse Charging
    • Fast System-Load-Transient Response
  • Dual-Remote-Sense Inputs
  • Monitor Outputs for
    • Adapter Current (4% Accuracy)
    • AC Adapter Detection
  • 11-Bit Battery Voltage Setting
  • 6-Bit Charge-Current/Input-Current Setting
  • 8A (max) Battery Charger Current
  • 11A (max) Input Current
  • +8V to +26V Input Voltage Range
  • Charges Li+, NiMH, and NiCd Battery Chemistries

Applications/Uses

  • Medical Devices
  • Notebook Computers
  • Portable Equipment with Rechargeable Batteries
  • Tablet PCs
Parametric specs for Battery Chargers
Charging VIN (V) (max) 26
Max. ICHG (A) 8
Cell Chemistry Li-Ion
Li-Polymer
# Lithium Ion Cells 1
2
3
4
Protected VIN (V) (max) 26
Charger (V) 0 to 19.2
Oper. Temp. (°C) -40 to +85
Package/Pins TQFN/28
Budgetary
Price (See Notes)
$7.54 @1k
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Simplified Block Diagram

MAX8731A: Typical Operating Circuit MAX8731A: Typical Operating Circuit Zoom icon

Technical Docs

Design & Development

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Description

The MAX8731A evaluation kit (EV kit) is an efficient, multi-chemistry battery charger. It uses the Intel system management bus (SMBus™) to control the battery-regulation voltage, charger current output, and input current-limit set point.

The MAX8731A EV kit can charge one, two, three, or four series Li+ cells with a current up to 8A. The MAX8731A evaluation system (EV system) consists of a MAX8731A EV kit and the Maxim SMBUSMON2 board. The MAX8731A EV kit includes Windows® 95/98/2000/XP-compatible software to provide a user-friendly interface.

View Details

Features

  • 0.5% Battery Voltage Accuracy
  • 3% Input Current-Limit Accuracy
  • 3% Battery Charge-Current Accuracy
  • Up to 8A Battery Charge Current
  • +8V to +25V Input Voltage Range
  • Charges Li+, NiCd, NiMH Battery Chemistries
  • Cycle-by-Cycle Current Limiting
  • SMBus-Compatible 2-Wire Serial Interface
  • Includes Windows 95/98/2000/XP-Compatible Software and Demo PCB
  • Fully Assembled and Tested

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Support & Training

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Parameters

Parametric specs for Battery Chargers
Charging VIN (V) (max) 26
Max. ICHG (A) 8
Cell Chemistry Li-Ion
Li-Polymer
# Lithium Ion Cells 1
2
3
4
Protected VIN (V) (max) 26
Charger (V) 0 to 19.2
Oper. Temp. (°C) -40 to +85
Package/Pins TQFN/28
Budgetary
Price (See Notes)
$7.54 @1k

Key Features

  • 0.5% Battery Voltage Accuracy
  • 3% Input Current-Limit Accuracy
  • 3% Charge-Current Accuracy
  • SMBus 2-Wire Serial Interface
  • Cycle-by-Cycle Current Limit
    • Battery Short-Circuit Protection
    • Fast Response for Pulse Charging
    • Fast System-Load-Transient Response
  • Dual-Remote-Sense Inputs
  • Monitor Outputs for
    • Adapter Current (4% Accuracy)
    • AC Adapter Detection
  • 11-Bit Battery Voltage Setting
  • 6-Bit Charge-Current/Input-Current Setting
  • 8A (max) Battery Charger Current
  • 11A (max) Input Current
  • +8V to +26V Input Voltage Range
  • Charges Li+, NiMH, and NiCd Battery Chemistries

Applications/Uses

  • Medical Devices
  • Notebook Computers
  • Portable Equipment with Rechargeable Batteries
  • Tablet PCs

Description

The MAX8731A is an SMBus™ programmable multi-chemistry battery charger. The MAX8731A uses a minimal command set to easily program the charge voltage, charge current, and adapter current limit.

The MAX8731A charges one to four Li+ series cells and delivers up to 8A charge current. The MAX8731A drives n-channel MOSFETs for improved efficiency and reduced cost. Low-offset current-sense amplifiers provide high accuracy with 10mΩ sense resistors.

The MAX8731A current-sense amplifiers provide high accuracy (3% at 3.5A) and also provide fast cycle-by-cycle current-mode control to protect against battery short circuit and system load transients.

The charger employs dual remote sense, which reduces charge time by measuring the feedback voltage directly at the battery, improving accuracy of initial transition into constant-voltage mode. The MAX8731A provides 0.5% battery voltage accuracy directly at the battery terminal.

The MAX8731A provides a digital output that indicates the presence of the AC adapter, as well as an analog output that indicates the adapter current within 4% accuracy.

The MAX8731A is available in a small 5mm x 5mm, 28-pin, thin (0.8mm) QFN package. An evaluation kit is available to reduce design time. The MAX8731A is available in a lead-free package.

Simplified Block Diagram

MAX8731A: Typical Operating Circuit MAX8731A: 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