ds2786 Maxim Integrated Products, Inc., ds2786 Datasheet - Page 5

• Manufacturer Part Number: ds2786
• Description: Ds2786 Standalone Ocv-based Fuel Gauge
• Manufacturer: Maxim Integrated Products, Inc.

DS2786 Standalone OCV-Based Fuel Gauge
Figure 2. Block Diagram
DESCRIPTION
The DS2786 provides current-flow, voltage, and temperature measurement data to support battery-capacity
monitoring in cost-sensitive applications. Current is measured bidirectionally over a dynamic range of ±51.2mV with
a resolution of 25µV. Assuming a 15mΩ sense resistor, the current sense range is ±3.4A, with a 1 LSB resolution
of 1.667mA. Current measurements are performed at regular intervals and accumulated with each measurement to
support “coulomb counting” during periods of host power consumption. Each current measurement is reported with
sign and magnitude in the two-byte Current Register. Battery voltage measurements are reported in the two-byte
Voltage Register with 12-bit (1.22mV) resolution, and auxiliary voltage measurements are reported in the two-byte
Aux Volt Registers with 11-bit resolution. Additionally, the Temperature Register reports temperature with 0.125ºC
resolution and ±3ºC accuracy from the on-chip sensor. The on-chip temperature measurement is optional and
replaces the auxiliary voltage channel AIN1.
The DS2786 provides accurate relative capacity measurements during periods of host system inactivity by looking
at cell open circuit voltage. Cell capacity is calculated using an OCV voltage profile and a 1-byte scale factor to
weight accumulated current during the coulomb-counting periods. The OCV voltage profile and scale factor are
stored in EEPROM memory. The EEPROM memory is constructed with a SRAM shadow so that the OCV voltage
profile and scale factor can be overwritten by the host to accommodate a variety of cell types and capacities from
2
multiple cell vendors. The I
C interface also allows read/write access to the Status, Configuration, and
Measurement Registers.
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