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DS2786
Stand-Alone OCV-Based Fuel Gauge

2-Wire Stand-Alone Fuel Gauge Requires No Learn Cycle to Provide Initial Capacity Estimate or Maintain Accuracy During Use


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Status
Active: In Production.

Data Sheet
FULL DATA SHEET (PDF, 316kB)
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Description
The DS2786 estimates available capacity for rechargeable Li-Ion and Li-Ion Polymer batteries based on the cell voltage in the open-circuit state following a relaxation period. The open-circuit voltage (OCV) is used to determine relative cell capacity based on a lookup table stored in the IC. This capability makes accurate capacity information available immediately after a battery pack is inserted. During periods of moderate to high rate discharging, which preclude OCV measurements, the DS2786 uses coulomb counting as a secondary means of estimating relative capacity.

Remaining capacity is reported in percent, along with cell voltage, current and temperature information. Cell characteristics and application parameters used in the calculations are stored in on-chip EEPROM.

The DS2786 is intended for use on the host side of portable devices, though it can also be mounted within a battery pack. Measurement and estimated capacity data are accessed through an I²C interface. Temperature data is available from an on-die sensor. Resistance measurements of a pack identification resistor and pack thermistor are supported by ratiometric measurements on two auxiliary inputs.

An evaluation kit is available:  DS2786EVKIT  

NOTE: This product requires use of the following:

  • DS2786K Evaluation Kit Software

    Key Features   Applications/Uses
    • Relative Capacity Calculated from Combination Coulomb Counter and Open-Circuit Cell Voltage (OCV) Battery Model
    • Accurate Warning of Low Battery Conditions Even On First Cycle (No Learn Cycle Needed)
    • 12-Bit Battery Voltage Measurement:
      • ±10mV Accuracy
      • 1.22mV LSB, 0V to 5V Input Range
    • 11-Bit Bidirectional Current Measurement:
      • 25µV LSB, ±51.2mV Dynamic Range
      • 1.67mA LSB, ±3.4A (RSNS = 15mΩ)
    • Current Accumulation Measurement Resolution:
      • ±204.8mVh Range
      • ±13.65Ah (RSNS = 15mΩ)
    • Internal Temperature Measurement:
      • 0.125°C LSB, ±3°C Accuracy
    • Two 11-Bit Aux Input Voltage Measurements:
      • ±8 LSB Accuracy, Ratiometric Inputs Eliminate Supply Accuracy Issues
    • VOUT Pin Drives Resistive Dividers, Reduces Current Consumption
    • 2-Wire Interface
    • Low Power Consumption:
      • Active Current: 50µA typ, 80µA max
      • Sleep Current: 1µA typ, 3µA max

     
  • 3G Multimedia Wireless Handsets
  • Digital Audio (MP3) Players
  • Digital Still Cameras

    Diagram
    DS2786: Typical Operating Circuit
    Typical Operating Circuit

    Application Notes
  • Application Note 3978: Getting Started with the DS2786K - DS2786
  • Application Note 3992: Interpreting the Open-Circuit-Voltage (OCV) Fuel Gauge of the DS2786 - DS2786
  • Application Note 4106: Using the DS2786 Battery Fuel Gauge in a 2-Cell Battery Pack - DS2786
  • Application Note 4141: Programming and Testing a DS2786-Based Circuit - DS2786
  • Application Note 4189: Characterizing a Lithium-Ion (Li+) Cell for Use with an Open-Circuit-Voltage (OCV) Based Fuel Gauge - DS2786
  • Application Note 4224: Using the DS2786 Battery Fuel Gauge in the Host Side of a 2-Cell Battery Application - DS2786

    Evaluation Kits
  • DS2786EVKIT

    Design Guides
  • Power Management for Battery-Powered Equipment (PDF)

    Reliability Reports
  • Reliability Report: DS2786.pdf

    Software/Models
  • DS2786K Evaluation Kit Software

    Ordering Information
    Notes:

    1. Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.
    2. Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.
    3. Part number suffixes: T or T&R = tape and reel;+ = RoHS/lead-free;# = RoHS/lead-exempt. More: SeeFull Data Sheet or Part Naming Conventions.
    4. * Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.


    Devices: 1-4 of 4

    DS2786 Free
    Sample
    Buy Status
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    Temp RoHS/Lead-Free?
    Materials Analysis
    DS2786G+  
    Active TDFN-EP;10 pin;10 mm²
    Outline Drawing: 21-0137 (PDF)
    Land Pattern: 90-0003 (PDF)
    Use pkgcode/variation: T1033+1*
    -40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS2786G+T&R    
    Active TDFN-EP;10 pin;10 mm²
    Outline Drawing: 21-0137 (PDF)
    Land Pattern: 90-0003 (PDF)
    Use pkgcode/variation: T1033+1*
    -40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS2786G-C03+T&R    
    Active TDFN-EP;10 pin;10 mm²
    Outline Drawing: 21-0137 (PDF)
    Land Pattern: 90-0003 (PDF)
    Use pkgcode/variation: T1033+1*
    -40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS2786G-5+T&R    
    Active TDFN;10 pin;11 mm²
    Outline Drawing: 21-0268 (PDF)
    Land Pattern: 90-0247 (PDF)
    Use pkgcode/variation: T1034N+1*
    -40°C to +85°C See data sheet

    More Information
  • New Product Press Release 2007-02-20 
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    Document Ref.: 19-4637; 2009-06-22
    This page last modified: 2009-09-01


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