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DS2755
High-Accuracy Battery Fuel Gauge with Snapshot
www.maxim-ic.com
FEATURES
Snapshot Mode Allows Instantaneous Power Measurement Accurate Current Measurement for Coulomb Counting (Current Accumulation) - 2% ±4μV over ±64mV Input Range - 2% ±200μA over ±3.2A Range Using a 20mΩ Sense Resistor Current Measurement - 9-Bit Bidirectional Snapshot Measurement - 12-Bit Bidirectional Average Updated Every 88ms - 15-Bit Bidirectional Average Updated Every 2.8s Voltage Measurement - 9-Bit Snapshot Measurement - 10-Bit Measurement Updated Every 4ms Temperature Measurement - 10-Bit Measurement, 0.125°C Resolution Using Integrated Sensor Host Alerted When Accumulated Current or Temperature Exceeds User-Selectable Limits 96 Bytes of Lockable EEPROM 8 Bytes of General-Purpose SRAM Dallas 1-Wire® Interface with Unique 64-Bit Device Address with Standard 16kbps or Overdrive 142kbps Timing 3mm Dimension of 8-Pin TSSOP Package Allows Mounting on Side of Thin Prismatic Li+ and Li+/Polymer Cells
PIN CONFIGURATION
VIN VSS PIO VDD 1 2 2 3 2 4 8 7 6 5 DQ SNS IS2 IS1
DS2755E 8-Pin TSSOP Package
DESCRIPTION
The DS2755 high-precision battery fuel gauge is a data-acquisition and information-storage device tailored for cost-sensitive and space-constrained 1cell Li+/polymer battery-pack applications. The DS2755 provides the key hardware components required to accurately estimate remaining capacity by integrating low-power, precision measurements of temperature, voltage, current, and current accumulation, as well as nonvolatile (NV) data storage, into the small footprint of a 3.0mm x 4.4mm 8-pin TSSOP package. Through its 1-Wire interface, the DS2755 gives the host system read/write access to status and control registers, instrumentation registers, and generalpurpose data storage. Each device has a unique factory-programmed 64-bit net address that allows it to be individually addressed by the host system, supporting multibattery operation.
APPLICATIONS
Cell Phones Digital Cameras Smartphones PDAs Portable Consumer Products
ORDERING INFORMATION
PART DS2755E+ DS2755E+T&R MARKING 2755 2755 TEMP RANGE -20°C to +70°C -20°C to +70°C DESCRIPTION 8-Pin TSSOP, Lead Free DS2755E+ on Tape-and-Reel
1-Wire is a registered trademark of Dallas Semiconductor.
Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata.
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DS2755: High-Accuracy Battery Fuel Gauge with Snapshot
DESCRIPTION (CONTINUED)
The DS2755 performs temperature, voltage, and current measurement to a resolution sufficient to support processmonitoring applications such as battery charge control and remaining capacity estimation. Temperature is measured using an on-chip sensor, eliminating the need for a separate thermistor. Bidirectional current measurement supporting current accumulation (coulomb counting) is accomplished using an external current sense resistor. The host system can configure the DS2755 to signal critical conditions to reduce polling overhead. The interrupt fires when programmable upper and lower thresholds of temperature or coulomb count are crossed. The user can select either the DQ pin or PIO pin as the interrupt signal. The programmable I/O pin allows the host system to sense and control other electronics in the pack, including switches, vibration motors, speakers, and LEDs, or the I/O pin can be configured as an interrupt output. Three types of memory are provided on the DS2755 for battery information storage: EEPROM, lockable EEPROM, and SRAM. EEPROM memory saves important battery data in true NV memory that is unaffected by severe battery depletion, accidental shorts, or ESD events. Lockable EEPROM becomes ROM when locked to provide additional security for unchanging battery data. SRAM provides inexpensive storage for temporary data.
Figure 1. APPLICATION EXAMPLE
PACK+
500 1k 150 150
PIO DATA
1 Cell Li+
5.6V (1)
VIN VSS PIO VDD
103
DQ SNS IS2 IS1
5.6V (1) 5.6V (1) 102 104
Protection IC (Li+/Polymer)
DS2755
RSNS
2.5V (1)
PACK (1) Optional component(s) for robust ESD performance
SNS
10kΩ 10kΩ
VSS RKS IS1 ADC Input DS2755
RKS IS2
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DS2755: High-Accuracy Battery Fuel Gauge with Snapshot
ABSOLUTE MAXIMUM RATINGS*
Voltage on PIO Pin, Relative to VSS Voltage on All Other Pins, Relative to VSS Continuous Sink Current, DQ, PIO Operating Temperature Range Storage Temperature Range Soldering Temperature -0.3V to +12V -0.3V to +6V 12mA -40°C to +85°C -55°C to +125°C See J-STD-020 Specification
* 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 rel.