DS2786B Datasheet, PDF (1/21 Pages) Maxim Integrated Products – Stand-Alone OCV-Based Fuel Gauge

19-5223; Rev 1; 4/10
Stand-Alone OCV-Based Fuel Gauge
General Description
The DS2786B estimates available capacity for recharge-
able Li-ion (Li+) and Li+ polymer batteries based on the
cell voltage in the open-circuit state following a relax-
ation 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 dis-
charging, 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 mea-
surements of a pack identification resistor and pack ther-
mistor 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 Still Cameras
Digital Audio (MP3) Players
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 (R_SNS = 15mΩ)
♦ Current Accumulation Measurement Resolution
±204.8mVh Range
±13.65Ah (R_SNS = 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
♦ V_OUT 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)
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
DS2786BG+
-20°C to +70°C 10 TDFN-EP*
DS2786BG+T&R
-20°C to +70°C 10 TDFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
T&R = Tape and reel.
Operating Diagram
Li+
PROTECTION
CIRCUIT
V_OUT
V_IN
DS2786B
AIN0
SDA
AIN1
SCL
V_SS
SNS
SYSTEM
μP
I²C
INTERFACE
R_SNS
(EEPROM PROGRAMMING TEST POINT NOT SHOWN)
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.