The DS2756 High precision battery fuel meter is a data acquisition and information storage device designed for cost-sensitive and space-limited 1-cell lithium-ion/polymer battery pack applications. By integrating precise measurements of low power consumption, temperature, voltage, current and current accumulation, and non-volatile (NV) data storage into a 3.0mm x 4.4mm 8-pin TSSOP package, key hardware components required for accurate estimation of residual capacity are provided.
And through its 1 - Wire interface, DS2756 provide host system for state and control registers, instrument register read/write access and general data storage. Each device has a unique factory-programmed 64-bit network address, allowing the host system to be individually addressed and supporting multi-battery operation.
DS2756 Pin arrangement
DS2756 Typical operating circuit
Describe in detail
The DS2756 performs temperature, voltage, and current measurements at a resolution sufficient to support process monitoring applications such as battery charge control and residual capacity estimation. Measuring temperature using on-chip sensors eliminates the need for a separate thermistor. Bidirectional current measurement supports current accumulation (coulomb counting) accomplished using an external current sensing resistor.
The host system can configure the DS2756 to signal critical conditions to reduce polling overhead. An alarm interrupts the fire when programmable upper and lower thresholds for temperature or coulomb counts are crossed. Users can select DQ pins or PIO pins as the alarm interrupt signal. The PIO can also interrupt the output as a pause mode to reduce idle current consumption in the battery pack.
In suspension mode, the DS2756 cycles between active and suspension mode to reduce the DS2756 power current, and the PIO pins can be used to wake up microcontrollers or other packaged circuits when the current flowing through the package exceeds the programmable charge-discharge threshold (See the picture below).
Alarm and pause mode operation diagram
The gap between the current measurement programmable implementation average current as low as 10μA (see chart).As a universal I/O pin, PIO allows the host system to sense and control other electronics in the package, including switches, vibrating motors, speakers, and leds.
Three types of memory are provided on the DS2756 for battery information storage :EEPROM, Lockable EEPROM, and SRAM. EEPROM memory keeps important battery data in true NV memory, safe from severe battery depletion, accidental short-circuiting, or ESD events. Lockable EEPROM becomes ROM when locked, providing additional security for unchanging battery data. SRAM provides inexpensive storage for temporary data.
An application example of a microcontroller in Pack
Features
● Programmable pause mode
● Accurate current accumulation
- Over 2% plus or ± 4μV + 64mv Input Range
- 2% plus or ±200μA over ±3.2A with 20 mΩ Sense
● Current measurement
- 9-bit snapshot measurement
- 12 bits are updated every 88 milliseconds on average
- 15-bit average updates every 2.8 seconds
● Voltage measurement
- 9-bit snapshot measurement
- 10 bits are updated every 4 milliseconds on average
● Temperature measurement
- 10 - Bit with 0.125℃ Resolution
● Snapshot mode allows instantaneous power measurement
● When cumulative current or Temperature exceeds programmable limit
● 96-byte lockable EEPROM
● 8 bytes of universal SRAM
● Dallas 1 - wire interface, unique 64 - bit Address and standard or overspeed timing
● The 8-pin TSSOP package size is 3mm Allows installation on thin prism side Li+ and Li+/ polymer batteries
