DS2786_09 Datasheet, PDF (1/22 Pages) Maxim Integrated Products – Stand-Alone OCV-Based Fuel Gauge

19-4637; 5/09
www.maxim-ic.com
GENERAL 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.
APPLICATIONS
3G Multimedia Wireless Handsets
Digital Still Cameras
Digital Audio (MP3) Players
TYPICAL OPERATING CIRCUIT
DS2786
Stand-Alone OCV-Based
Fuel Gauge
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:
25V LSB, ±51.2mV Dynamic Range
1.67mA LSB, ±3.4A (R_SNS = 15m)
 Current Accumulation Measurement
Resolution:
±204.8mVh Range
±13.65Ah (R_SNS = 15m)
 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
 V_OUT Pin Drives Resistive Dividers, Reduces
Current Consumption
 2-Wire Interface
 Low Power Consumption:
Active Current: 50A typ, 80A max
Sleep Current: 1A typ, 3A max
ORDERING INFORMATION
PART
TEMP RANGE PIN-PACKAGE
DS2786G+
-20ºC to +70ºC 10 TDFN-EP*
DS2786G+T&R -20ºC to +70ºC 10 TDFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
*EP = Exposed pad.
PIN CONFIGURATION
Commands, Registers, and Modes are capitalized for clarity.
1 of 22
3mm x 3mm TDFN-10
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