DS2784
1-Cell Fuel Gauge with FuelPack,
Protector, and SHA-1 Authentication
General Description
The DS2784 operates from 2.5V to 4.6V for integration in
battery packs using a single lithium-ion (Li+) or Li+ poly-
mer cell. Available capacity is reported in mAh and as a
percentage. Safe operation is ensured with the included
Li+ protection function and SHA-1-based challenge-
response authentication.
Precision measurements of voltage, temperature, and
current, along with cell characteristics and application
parameters are used to estimate capacity. The available
capacity registers report a conservative estimate of the
amount of charge that can be removed given the current
temperature and discharge rate.
In addition to the nonvolatile (NV) storage for cell compen-
sation and application parameters, 16 bytes of EEPROM
memory is made available for the exclusive use of the
host system and/or pack manufacturer. This facilitates
battery lot and date tracking or NV storage of system or
battery usage statistics.
A 1-Wire
®
interface provides serial communication at
16kbps or 143kbps to access data registers, control
registers, and user memory. Additionally, 1-Wire com-
munication enables challenge-response pack authentica-
tion using SHA-1 as the hash algorithm in a hash-based
message authentication code (HMAC) authentication
protocol.
Features
●
Precision Voltage, Temperature, and Current
Measurement System
●
Available Capacity Estimated from Coulomb
Count, Discharge Rate, Temperature, and Cell
Characteristics
●
Estimates Cell Aging Using Learn Cycles
●
Uses Low-Cost Sense Resistor
●
Allows for Calibration of Gain and Temperature
Coefficient
●
Li+ Safety Circuitry—Overvoltage, Undervoltage,
Overcurrent, Short-Circuit Protection
●
Programmable Safety Thresholds for Overvoltage
and Overcurrent
●
Authentication Using SHA-1 Algorithm and 64-Bit
Secret
●
32-Byte Parameter EEPROM
●
16-Byte User EEPROM
●
Maxim 1-Wire Interface with 64-Bit Unique ID
●
Tiny, Pb-Free, 14-Pin TDFN Package Embeds Easily
in Battery Packs Using Thin Prismatic Cells
Applications
●
●
●
●
●
●
●
●
Health and Fitness Monitors
Digital Still, Video, and Action Cameras
Medical Devices
Handheld Computers and Terminals
Handheld Radios
Home and Building Automation, Sensors
Smart Batteries
Power Tools
Simple Fuel Gauge Circuit Diagram
PK+
1K
DC
1K
CC
1K
150
1K
DATA
150
PLS
DQ
PIO
VDD
VIN
CP
CTG
DS2784
SNS
VSS
RSNS
Ordering Information
appears at end of data sheet.
5.1V
0.1µF
0.1µF
Modes and commands are capitalized for clarity.
1-Wire is a registered trademark of Maxim Integrated Products,
Inc.
PK-
19-4636; Rev 5; 1/17
DS2784
1-Cell Fuel Gauge with FuelPack,
Protector, and SHA-1 Authentication
Absolute Maximum Ratings
Voltage Range on PLS Pin Relative to V
SS
..........-0.3V to +18V
Voltage Range on CP Pin Relative to V
SS
...........-0.3V to +12V
Voltage Range on DC
Pin Relative to V
SS
...............................-0.3V to (VCP + 0.3V)
Voltage Range on CC
Pin Relative to V
SS
.........................V
DD
- 0.3V to V
CP
+ 0.3V
Voltage Range on All
Other Pins Relative to V
SS
...............................-0.3V to +6.0V
Maximum Voltage Range on
V
IN
Pin Relative to V
DD
........................................ V
DD
+ 0.3V
Continuous Sink Current, PIO, DQ ....................................20mA
Continuous Sink Current, CC, DC......................................10mA
Operating Temperature Range ........................... -40°C to +85°C
Storage Temperature Range ............................ -55°C to +125°C
Lead Temperature (soldering,10s) .................................. ±300°C
Soldering Temperature (reflow) .......................................+260°C
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 reliability.
Electrical Characteristics
(V
DD
= 2.5V to 4.6V, T
A
= -20°C to +70°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Supply Voltage
SYMBOL
V
DD
I
DD0
Supply Current
I
DD1
I
DD2
I
DD3
Temperature Accuracy
Temperature Resolution
Temperature Range
Voltage Accuracy, V
IN
Voltage Resolution, V
IN
Voltage Range, V
IN
Input Resistance, V
IN
Current Resolution
Current Full Scale
Current Gain Error
Current Offset
Accumulated Current Offset
Time Base Error
CP Output Voltage
CP Startup Time
Output High: CC, DC
Output Low: CC
V
CP
t
SCP
V
OHCC
V
OHDC
V
OLCC
(Notes 2, 3, 4)
(Notes 2, 3, 4)
0°C ≤ T
A
≤ +50°C
I
CC
+ I
DC
= 0.9μA
CE = 0, DE = 0, C
CP
= 0.1μF, Active mode
-51.2
-1
-15
-360
-2
-3
8.50
V
CP
-
0.4
V
DD
+
0.1
9.25
0
15
1.56
+51.2
+1
+25
0
+2
+3
10.00
200
4.0 ≤ V
IN
≤ 4.6, V
IN
≤ V
DD
+ 0.3V
2.5 ≤ V
IN
≤ 4.6V, V
IN
≤ V
DD
+ 0.3V
-128.000
-30
-50
4.88
4.6
(Note 1)
Sleep mode
Sleep mode, V
DD
= 2.5V 0°C to +50°C
Active mode
Active mode during SHA computation
-3
0.125
+127.875
30
+50
CONDITIONS
MIN
+2.5
1
0.4
85
300
TYP
MAX
+4.6
4
1.5
125
500
+3
°C
°C
°C
mV
mV
V
MΩ
µV
mV
% full
scale
µV
µVh/day
%
V
ms
V
V
µA
UNITS
V
I
OH
= -100μA (Note 5)
I
OL
= 100μA
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Maxim Integrated
│
2
DS2784
1-Cell Fuel Gauge with FuelPack,
Protector, and SHA-1 Authentication
Electrical Characteristics (continued)
(V
DD
= 2.5V to 4.6V, T
A
= -20°C to +70°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Output Low: DC
DQ, PIO Voltage Range
DQ, PIO Input-Logic High
DQ, PIO Input-Logic Low
DQ, PIO Output-Logic Low
DQ, PIO Pullup Current
DQ, PIO Pulldown Current
DQ Input Capacitance
DQ Sleep Timeout
PIO, DQ Wake Debounce
SHA-1 COMPUTATION TIMING
Computation Time
V
IH
V
IL
V
OL
I
PU
I
PD
C
DQ
t
SLEEP
t
WDB
V
DQ
< V
IL
Sleep mode
2
100
30
I
OL
= 4mA
Sleep mode, V
PIN
= V
DD
- 0.4V
Active mode, V
PIN
= 0.4V
0.2
0.2
50
9
SYMBOL
V
OLDC
I
OL
= 100µA
-0.3
1.5
0.6
0.4
CONDITIONS
MIN
TYP
MAX
0.1
+5.5
UNITS
V
V
V
V
V
µA
µA
pF
s
ms
ms
t
SHA
Electrical Characteristics: Protection Circuit
(V
DD
= 2.5V to 4.6V, T
A
= 0°C to +50°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Overvoltage Detect
Charge-Enable Voltage
Undervoltage Detect
Overcurrent Detect: Charge
Overcurrent Detect:
Discharge
Short-Circuit Current Detect
Overvoltage Delay
Undervoltage Delay
Overcurrent Delay
Short-Circuit Delay
Test Threshold
Test Current
PLS Pulldown Current
Recovery Current
SYMBOL
V
OV
V
CE
V
UV
V
COC
V
DOC
V
SC
t
OVD
t
UVD
t
OCD
t
SCD
V
TP
I
TST
I
PPD
I
RC
COC, DOC conditions
SC, COC, DOC condition
Sleep mode
VUV condition, max: V
PLS
= 15V,
V
DD
= 1V min: V
PLS
= 4.2V, V
DD
= 2V
OC = 11b
OC = 00b
OC = 11b
OC = 00b
SC = 1b
SC = 0b
(Note 6)
(Notes 6, 7)
V
OV
= 11000b
V
OV
= 00011b
Relative to V
OV
CONDITIONS
MIN
4.457
4.252
-75
2.40
-57
-15.5
76
23.5
240
120
425
84
8
80
0.3
10
30
2.5
10
120
0.8
20
200
5.0
TYP
4.482
4.277
-100
2.45
-72
-23.5
96
35.5
300
150
MAX
4.507
4.302
-125
2.50
-87
-31.5
116
47.5
360
180
1150
680
12
160
1.5
40
600
10.00
UNITS
V
mV
V
mV
mV
mV
ms
ms
ms
µs
V
µA
µA
mA
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Maxim Integrated
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3
DS2784
1-Cell Fuel Gauge with FuelPack,
Protector, and SHA-1 Authentication
EEPROM Reliability Specification
(V
DD
= 2.5V to 4.6V, T
A
= -20°C to +70°C, unless otherwise noted.)
PARAMETER
EEPROM Copy Time
EEPROM Copy Endurance
SYMBOL
t
EEC
N
EEC
T
A
= +50°C
50,000
CONDITIONS
MIN
TYP
MAX
10
UNITS
ms
cycles
Electrical Characteristics: 1-Wire Interface, Standard
(V
DD
= 2.5V to 4.6V, T
A
= -20°C to +70°C, unless otherwise noted.)
PARAMETER
Time Slot
Recovery Time
Write-0 Low Time
Write-1 Low Time
Read-Data Valid
Reset-Time High
Reset-Time Low
Presence-Detect High
Presence-Detect Low
SYMBOL
t
SLOT
t
REC
t
LOW0
t
LOW1
t
RDV
t
RSTH
t
RSTL
t
PDH
t
PDL
480
480
15
60
960
60
240
CONDITIONS
MIN
60
1
60
1
120
15
15
TYP
MAX
120
UNITS
µs
µs
µs
µs
µs
µs
µs
µs
µs
Electrical Characteristics: 1-Wire Interface, Overdrive
(V
DD
= 2.5V to 4.6V, T
A
= -20°C to +70°C.)
PARAMETER
Time Slot
Recovery Time
Write-0 Low Time
Write-1 Low Time
Read-Data Valid
Reset-Time High
Reset-Time Low
Presence-Detect High
Presence-Detect Low
Note
Note
Note
Note
Note
Note
1:
2:
3:
4:
5:
6:
SYMBOL
t
SLOT
t
REC
t
LOW0
t
LOW1
t
RDV
t
RSTH
t
RSTL
t
PDH
t
PDL
48
48
2
8
80
6
24
CONDITIONS
MIN
6
1
6
1
16
2
2
TYP
MAX
16
UNITS
µs
µs
µs
µs
µs
µs
µs
µs
µs
All voltages are referenced to V
SS
.
Factory-calibrated accuracy. Higher accuracy can be achieved by in-system calibration by the user.
Accumulation bias and offset bias registers set to 00h. NBEN bit set to 0.
Parameters guaranteed by design.
CP pin externally driven to 10V.
Overvoltage and undervoltage delays (t
OVD
, t
UVD
) are reduced to 0s if the OV or UV condition is detected within 100ms of
entering Active mode.
Note 7:
t
UVD
MIN determined by stepping the voltage on V
IN
from V
UV
+ 250mV to V
UV
- 250mV.
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Embedded System
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