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DS2775, DS2776, DS2777, DS2778
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication

Industry's Smallest 2-Cell, Stand-Alone Fuel Gauge to Integrate an Li+ Protector and SHA-1 Authentication


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Status
Active: In Production.

Description
FULL DATA SHEET (PDF, 664kB)
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The DS2775–DS2778 report available capacity for rechargeable lithium-ion (Li+) and Li+ polymer (Li-Poly) batteries in mAh and as a percentage of full. Safe operation is ensured by the integrated Li+ protector. The DS2776/DS2778 support SHA-1-based challenge-response authentication in addition to all other DS2775/DS2777 features.

Precision measurements of voltage, temperature, and current, along with a cell characteristics table and application parameters, are used for capacity estimation calculations. The capacity registers report a conservative estimate of the amount of charge that can be removed given the current temperature, discharge rate, stored charge, and application parameters.

The DS2775–DS2778 operate from +4.0V to +9.2V for direct integration into battery packs with two Li+ or Li- Poly cells.

In addition to nonvolatile storage for cell compensation and application parameters, the DS2775–DS2778 offer 16 bytes of EEPROM for use by the host system and/or pack manufacturer to store battery lot and date tracking information. The EEPROM can also be used for nonvolatile storage of system and/or battery usage statistics. A Maxim 1-Wire® (DS2775/DS2776) or 2-wire (DS2777/DS2778) interface provides serial communication to access measurement and capacity data registers, control registers, and user memory. The DS2776/DS2778 use the SHA-1 hash algorithm in a challenge-response pack authentication protocol for battery-pack verification.

An evaluation kit is available:  DS2775EVKIT, DS2776EVKIT, DS2777EVKIT, DS2778EVKIT  

Key Features   Applications/Uses
  • High-Side nFET Drivers and Protection Circuitry
  • Precision Voltage, Temperature, and Current Measurement System
  • Cell-Capacity Estimation from Coulomb Count, Discharge Rate, Temperature, and Cell Characteristics
  • Estimates Cell Aging Between Learn Cycles
  • Uses Low-Cost Sense Resistor
  • Allows Calibration of Gain and Temperature Coefficient
  • Programmable Thresholds for Overvoltage and Overcurrent
  • Pack Authentication Using SHA-1 Algorithm (DS2776/DS2778)
  • 32-Byte Parameter EEPROM
  • 16-Byte User EEPROM
  • Maxim 1-Wire Interface with 64-Bit Unique ID (DS2775/DS2776)
  • 2-Wire Interface with 64-Bit Unique ID (DS2777/DS2778)
  • 3mm x 5mm, 14-pin TDFN Lead-Free Package

 

Key Specifications:  Battery Protectors, Selectors and Monitors
Part Number Functions Battery Type Interface User Data Storage
(Bytes)
Parameters Measured Battery Protection VSUPPLY
(V)
VSUPPLY
(V)
Package/Pins Smallest Available Pckg.
(mm2)
Oper. Temp.
(°C)
Price
min max max w/pins See Notes
DS2775 
Fuel Gauge
Protector
Status Monitor
2 Cell Li-Ion 1-Wire 16 EEPROM
Current
Temperature
Time
Voltage
Over Voltage
Over-Current
Over/Under Voltage
4 9.2
TDFN/14
15 -20 to +70 $2.73 @1k
DS2776  1-Wire
TDFN/14
$2.93 @1k
DS2777  2-Wire
TDFN/14
$3.18 @1k
DS2778  2-Wire
TDFN/14
$2.93 @1k
See All Battery Protectors, Selectors and Monitors (25)

Diagram
DS2775, DS2776, DS2777, DS2778: Typical Application Circuits
Typical Application Circuits

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    Document Ref.: 19-4688; 2009-07-22
    This page last modified: 2009-07-22


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