19-4636; Rev 8/09
DS2784
1-Cell Stand-Alone Fuel Gauge IC with
Li+ Protector and SHA-1
www.maxim-ic.com
GENERAL DESCRIPTION
The DS2784 operates from 2.5V to 4.6V for integration
in battery packs using a single lithium-ion (Li+) or Li+
polymer 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
compensation 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
communication enables challenge-response pack
authentication 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
Dallas 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
Smartphones/PDAs
Digital Still and Video Cameras
Cordless VoIP Phones
Portable GPS Navigation
Modes and commands are capitalized for clarity.
1-Wire is a registered trademark of Maxim Integrated Products, Inc.
PIN CONFIGURATION
ORDERING INFORMATION
PART
DS2784G+
DS2784G+T&R
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
TOP MARK
DS2784
DS2784
PIN PACKAGE
14 TDFN (3mm x 5mm)
14 TDFN (3mm x 5mm)
+Denotes
a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
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DS2784: 1-Cell Stand-Alone Fuel Gauge IC with Li+ Protector and SHA-1 Authentication
ABSOLUTE MAXIMUM RATINGS
Voltage Range on PLS Pin Relative to V
SS
Voltage Range on CP Pin Relative to V
SS
Voltage Range on DC Pin Relative to V
SS
Voltage Range on CC Pin Relative to V
SS
Voltage Range on All Other Pins Relative to V
SS
Maximum Voltage Range on V
IN
Pin Relative to V
DD
Continuous Sink Current, PIO, DQ
Continuous Sink Current, CC, DC
Operating Temperature Range
Storage Temperature Range
Soldering Temperature (10s)
-0.3V to +18V
-0.3V to +12V
-0.3V to (CP + 0.3V)
V
DD
- 0.3V to CP + 0.3V
-0.3V to +6.0V
V
DD
+ 0.3V
20mA
10mA
-40°C to +85°C
-55°C to +125°C
Refer to the IPC/JEDEC 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 reliability.
ELECTRICAL CHARACTERISTICS
(V
DD
= 2.5V to 4.6V, T
A
= -20C to +70C, unless otherwise noted. Typical values are at T
A
= +25C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
Supply Voltage
V
DD
(Note 1)
+2.5
+4.6
I
DD0
Sleep mode
1
4
Sleep mode, V
DD
= 2.5V
0.4
1.5
I
DD1
0C to +50C
Supply Current
I
DD2
Active mode
85
125
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
Output Low: DC
V
CP
t
SCP
V
OHCC
V
OHDC
V
OLCC
V
OLDC
(Notes 2, 3, 4)
(Notes 2, 3, 4)
0ºC
≤
T
A
≤
+50ºC
-51.2
-1
-15
-360
-2
-3
I
CC
+ I
DC
= 0.9µA
CE = 0, DE = 0,
C
CP
= 0.1µF, Active mode
I
OH
= -100µA (Note 5)
I
OL
= 100µA
I
OL
= 100µA
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V
CP
- 0.4
V
DD
+ 0.1
0.1
8.50
9.25
4.0
≤
V
IN
≤
4.6,
V
IN
≤
V
DD
+ 0.3V
2.5
≤
V
IN
≤
4.6V,
V
IN
≤
V
DD
+ 0.3V
Active mode during SHA
computation
-3
0.125
-128.000
-30
-50
4.88
0
15
1.56
+51.2
+1
+25
0
+2
+3
10.00
200
4.6
300
500
+3
+127.875
30
mV
+50
mV
V
M
V
mV
% full
scale
V
Vh/day
%
V
ms
V
V
V
UNITS
V
A
A
o
C
DS2784: 1-Cell Stand-Alone Fuel Gauge IC with Li+ Protector and SHA-1 Authentication
EEPROM RELIABILITY SPECIFICATION
(V
DD
= 2.5V to 4.6V, T
A
= -20C to +70C, 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
= -20C to +70C, 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
s
s
s
s
s
s
s
s
s
ELECTRICAL CHARACTERISTICS: 1-Wire Interface, Overdrive
(V
DD
= 2.5V to 4.6V, T
A
= -20C to +70C.)
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 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
SYMBOL
t
SLOT
t
REC
t
LOW0
t
LOW1
t
RDV
t
RSTH
t
RSTL
t
PDH
t
PDL
CONDITIONS
MIN
6
1
6
1
TYP
MAX
16
UNITS
s
s
s
s
s
s
s
s
s
16
2
2
48
48
2
8
80
6
24
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.
t
UVD
MIN determined by stepping the voltage on V
IN
from V
UV
+ 250mV to V
UV
- 250mV.
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