DS2786

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:
  25V LSB, ±51.2mV Dynamic Range
  1.67mA LSB, ±3.4A (RSNS = 15m)
Current Accumulation Measurement Resolution:
  ±204.8mVh Range
  ±13.65Ah (RSNS = 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
VOUT Pin Drives Resistive Dividers, Reduces Current Consumption
2-Wire Interface
Low Power Consumption:
  Active Current: 50A typ, 80A max
  Sleep Current: 1A typ, 3A max


Application

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


Pinout




Specifications

Voltage on All Pins Except V_PROG Relative to V_SS ................................. -0.3V to +6V
Voltage on V_PROG Relative to V_{SS ........................................................} -0.3V to +18V
Operating Temperature Range ............................................................ -40°C to +85°C
Storage Temperature Range ............................................................... -55°C to +125°C
Soldering Temperature ........................................................................ See IPC/JEDECJ-STD-020A

* This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.


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.