DS2786B

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


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Description

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).
DS2786B estimates available capacity for rechargeable Li-ion (Li+) and Li+ polymer batteries based on the cell voltage | Operating Diagram DS2786B estimates available capacity for rechargeable Li-ion (Li+) and Li+ polymer batteries based on the cell voltage | Operating Diagram Enlarge+

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 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)

Applications/Uses

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

See parametric specs for Battery Fuel Gauges, Protectors, and Monitors (52)


Part NumberFunctionsBattery TypeInterfaceUser Data Storage
(Bytes)
Parameters MeasuredApplicationsVSUPPLY
(V)
VSUPPLY
(V)
Package/PinsOper. Temp.
(°C)
Budgetary
Price
minmaxSee Notes
DS2786B Fuel Gauge1 Cell Li-Ion2-Wire32 EEPROM
Current
Temperature
Voltage
Host2.54.5
TDFN/10
-40 to +85$2.09 @1k

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.
Product Reliability Reports: DS2786B.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

Quality Management System >
Environmental Management System >

 
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