DS2786B

PRODUCTION

Stand-Alone OCV-Based Fuel Gauge

2-Wire Standalone Fuel Gauge Requires No Learn Cycle to Provide Initial Capacity Estimate or Maintain Accuracy During Use; Now Optimized for Smartphones with Push-Mail Feature

Data Sheet (Rev. 1) Product Selection Table
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Overview

  • 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 4.5V 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 Auxiliary 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)

The DS2786B estimates available capacity for rechargeable Li-ion (Li+) and Li+ 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 DS2786B 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 DS2786B 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.

The DS2786B comes in a 10-pin, lead-free, TDFN 3mm x 3mm package with an exposed pad (EP).

Applications

  • 3G Multimedia Wireless Handsets
  • Digital Audio (MP3) Players
  • Digital Still Cameras
DS2786B
Stand-Alone OCV-Based Fuel Gauge
DS2786B estimates available capacity for rechargeable Li-ion (Li+) and Li+ polymer batteries based on the cell voltage | Operating Diagram
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Data Sheet 1

Reliability Data 1

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