DS2775/DS2776/
DS2777/DS2778
2-Cell, Fuel Gauge with FuelPack,
Protector, and SHA-1 Authentication
General Description
Features
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.
● 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
Precision measurements of voltage, temperature, and
current, along with a cell characteristics table and applica-
tion parameters, are used for capacity estimation calcula-
tions. The capacity registers report a conservative esti-
mate of the amount of charge that can be removed given
the current temperature, discharge rate, stored charge,
and application parameters.
● Allows Calibration of Gain and Temperature
Coefficient
● Programmable Thresholds for Overvoltage and
Overcurrent
● Pack Authentication Using SHA-1 Algorithm
The DS2775–DS2778 operate from +4.0V to +9.2V
for direct integration into battery packs with two Li+ or
Li- Poly cells.
(DS2776/DS2778)
● 32-Byte Parameter EEPROM
● 16-Byte User EEPROM
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 non-
volatile storage of system and/or battery usage statistics.
● 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
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.
DS2775/DS2776 Simple Fuel Gauge
Circuit Diagram
Applications
PK+
● Health and Fitness Monitors
● Digital Still, Video, and Action Cameras
● Medical Devices
● Handheld Computers and Terminals
● Handheld Radios
1kΩ
150Ω
1kΩ
470Ω
1kΩ
1kΩ
CC
SRC
DC
PLS
DQ
V
DD
IN2
IN1
150Ω
DATA
V
V
1kΩ
DS2775
DS2776
PIO
VB
CP
● Home and Building Automation, Sensors
● Smart Batteries
0.47µF
5.1V
SNS
V
SS
OVD
0.1µF
0.1µF
SRC
● Power Tools
R
SNS
PK-
Ordering Information appears at end of data sheet.
Selector Guide appears at end of data sheet.
1-Wire is a registered trademark of Maxim Integrated Products, Inc.
19-4688; Rev 5; 2/17