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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

Product Details

Key Features

Parametric specs for Battery Fuel Gauges, Protectors, and Monitors
Functions Fuel Gauge
Battery Type 1 Cell Li-Ion
3-Cell NiMH
Interface 2-Wire
User Data Storage (Bytes) 32 EEPROM
Parameters Measured Current
Temperature
Voltage
End Equipment Host
VSUPPLY (V) (min) 2.5
VSUPPLY (V) (max) 5.5
Package/Pins TDFN/10
Oper. Temp. (°C) -40 to +85
Budgetary
Price (See Notes)
2.37
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Simplified Block Diagram

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Parameters

Parametric specs for Battery Fuel Gauges, Protectors, and Monitors
Functions Fuel Gauge
Battery Type 1 Cell Li-Ion
3-Cell NiMH
Interface 2-Wire
User Data Storage (Bytes) 32 EEPROM
Parameters Measured Current
Temperature
Voltage
End Equipment Host
VSUPPLY (V) (min) 2.5
VSUPPLY (V) (max) 5.5
Package/Pins TDFN/10
Oper. Temp. (°C) -40 to +85
Budgetary
Price (See Notes)
2.37

Key Features

  • 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

Applications/Uses

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

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.

Simplified Block Diagram

DS2786 estimates available capacity for rechargeable Li-Ion and Li-Ion Polymer batteries | Typical Operating Circuit DS2786 estimates available capacity for rechargeable Li-Ion and Li-Ion Polymer batteries | Typical Operating Circuit Zoom icon

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 .