age, battery current and its own temperature in portable
product applications. The wide input voltage range allows
use with multicell batteries up to 60V. A precision coulomb
counter integrates current through a sense resistor between
the battery’s positive terminal and the load or charger.
Voltage, current and temperature are measured with an
internal 14-bit No Latency ΔΣ™ ADC. The measurements
are stored in internal registers accessible via the onboard
I
2
C/SMBus Interface.
The LTC2944 features programmable high and low thresh-
olds for all four measured quantities. If a programmed
threshold is exceeded, the device communicates an alert
using either the SMBus alert protocol or by setting a flag
in the internal status register. The LTC2944 requires only
a single low value sense resistor to set the measured
current range.
All registered trademarks and trademarks are the property of their respective owners.
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Measures Accumulated Battery Charge
and Discharge
3.6V to 60V Operating Range for Multiple Cells
14-Bit ADC Measures Voltage, Current
and Temperature
1% Voltage, Current and Charge Accuracy
±50mV Sense Voltage Range
High Side Sense
I
2
C Interface/SMBus Interface
General Purpose Measurements for Any Battery
Chemistry and Capacity
Configurable Alert Output/Charge Complete Input
Quiescent Current Less Than 150µA
Small 8-Lead 3mm × 3mm DFN Package
applicaTions
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Electric and Hybrid Electric Vehicles
Power Tools
Electric Bicycles, Motorcycles, Scooters
High Power Portable Equipment
Photo Voltaics
Backup Battery Systems
Typical applicaTion
3.3V
CHARGER
1µF
SENSE
+
SENSE
–
GND
R
SENSE
50m
+
MULTICELL
Li-ION
CHARGE ERROR (%)
2k
V
DD
µP
2k
2k
ALCC
SDA
SCL
LTC2944
1A
LOAD
3
2
1
0
–1
–2
2944 TA01a
Total Charge Error vs
Differential Sense Voltage
V
SENSE+
= 3.6V TO 60V
–3
0.1
1
V
SENSE
(mV)
10
100
2944 TA01b
2944fa
For more information
www.linear.com/LTC2944
1
LTC2944
absoluTe MaxiMuM raTings
(Notes 1, 2)
pin conFiguraTion
TOP VIEW
SENSE
+
GND
GND
SCL
1
2
3
4
9
8 SENSE
–
7 GND
6
ALCC
5 SDA
Supply Voltage (SENSE
+
) ........................... –0.3V to 65V
SCL, SDA,
ALCC
Voltage .............................. –0.3V to 6V
SENSE
–
...............(–0.3V + V
SENSE+
) to (V
SENSE+
+ 0.3V)
Operating Ambient Temperature Range
LTC2944C ............................................... 0°C to 70°C
LTC2944I ............................................–40°C to 85°C
Storage Temperature Range .................. –65°C to 150°C
DD PACKAGE
8-LEAD (3mm
×
3mm) PLASTIC DFN
T
JMAX
= 150°C,
θ
JA
= 100°C/W
EXPOSED PAD (PIN 9) PCB GND CONNECTION OPTIONAL
orDer inForMaTion
LEAD FREE FINISH
LTC2944CDD#PBF
TAPE AND REEL
LTC2944CDD#TRPBF
http://www.linear.com/product/LTC2944#orderinfo
PART MARKING*
LGCR
PACKAGE DESCRIPTION
8-Lead (3mm × 3mm) Plastic DFN
TEMPERATURE RANGE
0°C to 70°C
LTC2944IDD#PBF
LTC2944IDD#TRPBF
LGCR
8-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 2)
SYMBOL
V
SENSE+
I
SUPPLY
I
SENSE+
I
SENSE–
V
UVLO
V
SENSE
R
IDR
q
LSB
PARAMETER
Supply Voltage
Supply Current (Note 3)
Battery Gas Gauge On, ADC Sleep
Battery Gas Gauge On, ADC On
Shutdown
Battery Gas Gauge On, ADC Sleep
Battery Gas Gauge On, ADC On
Shutdown
Battery Gas Gauge On, ADC Sleep
Battery Gas Gauge On, ADC On
Shutdown
V
SENSE+
Falling
V
SENSE+
– V
SENSE–
l
elecTrical characTerisTics
CONDITIONS
l
l
l
l
MIN
3.6
TYP
MAX
60
UNITS
V
µA
µA
µA
µA
µA
µA
µA
µA
µA
Power Requirements
80
850
15
80
500
15
1
350
1
3.0
3.5
3.6
±50
400
Prescaler M = 4096(Default), R
SENSE
= 50mΩ
0.340
150
950
30
Pin Current (Note 3)
Pin Current (Note 3)
Undervoltage Lockout Threshold
Sense Voltage Differential Input
Range
Differential Input Resistance Across
SENSE
+
and SENSE
–
(Note 8)
Charge LSB (Note 4)
V
mV
kΩ
mAh
2944fa
Coulomb Counter
l
2
For more information
www.linear.com/LTC2944
LTC2944
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
SYMBOL
TCE
PARAMETER
Total Charge Error (Note 5)
CONDITIONS
10mV ≤ |V
SENSE
| ≤ 50mV DC
10mV ≤ |V
SENSE
| ≤ 50mV DC
1mV ≤ |V
SENSE
| ≤ 10mV DC (Note 8)
V
SENSE
≥ 500µV, V
SENSE
+ = 30V
l
l
l
elecTrical characTerisTics
MIN
TYP
MAX
±1
±1.5
±3.5
UNITS
%
%
%
µV
V
OSE
Effective Differential Offset Voltage
(Note 9)
Resolution (No Missing Codes)
5
10
Voltage Measurement ADC
(Note 8)
(Note 6)
l
14
70.8
4.32
1
1.3
1.3
±1
±4
48
12
±64
±50
31.25
1
1.3
±1
±10
±4
8
11
510
0.25
±3
±5
8
0.8
0.5
2.2
1.8
0.4
1
10
1
±1
Bits
V
mV
%
%
%
LSB
ms
Bits
mV
mV
µV
%
%
LSB
LSB
ms
Bits
K
K
K
K
ms
V
V
V
µA
pF
µs
V
FS(V)
ΔV
LSB
TUE
V
Gain
V
INL
V
T
CONV(V)
Full-Scale Voltage Conversion
Quantization Step of 14-Bit Voltage
ADC
Voltage Total Unadjusted Error
l
Voltage Gain Accuracy
Integral Nonlinearity
Voltage Conversion Time
Resolution (No Missing Codes)
(Note 8)
V
SENSE+
– V
SENSE–
(Note 6)
l
l
l
Current Measurement ADC
l
V
FS(I)
V
SENSE
ΔI
LSB
Gain
I
V
OS(I)
INL
I
T
CONV(I)
Full-Scale Current Conversion
Sense Voltage Differential Input
Range
Quantization Step of 12-Bit Current
ADC
Current Gain Accuracy
l
l
Offset
Integral Nonlinearity
Current Conversion Time
Resolution (No Missing Codes)
(Note 8)
(Note 6)
l
l
Temperature Measurement ADC
l
T
FS
ΔT
LSB
TUE
T
T
CONV(T)
V
ITH(HV)
V
ITH(LV)
V
OL
I
IN
C
IN
t
PCC
Full-Scale Temperature
Quantization Step of 11-Bit
Temperature ADC
Temperature Total Unadjusted Error V
SENSE+
≥ 5V
(Note 8)
Temperature Conversion Time
Logic Input Threshold
Low Level Output Voltage,
ALCC,
SDA
Input Leakage,
ALCC,
SCL, SDA
Input Capacitance, ,
ALCC,
SCL,
SDA
Minimum Charge Complete (CC)
Pulse Width
V
SENSE+
≥ 5V
3.6V < V
SENSE+
< 5V
I = 3mA, V
SENSE+
≥ 5V
V
IN
= 5V
(Note 8)
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l
Digital Inputs and Digital Outputs
l
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l
l
2944fa
For more information
www.linear.com/LTC2944
3
LTC2944
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
SYMBOL
f
SCL(MAX)
t
BUF(MAX)
PARAMETER
Maximum SCL Clock Frequency
Bus Free Time Between Stop/Start
CONDITIONS
l
l
l
l
l
l
l
l
elecTrical characTerisTics
MIN
400
TYP
900
MAX
UNITS
kHz
I
2
C Timing Characteristics
1.3
600
600
600
100
50
0.3
20 + 0.1 •
C
B
0.9
300
µs
ns
ns
ns
ns
ns
µs
ns
t
SU(STA(MIN))
Minimum Repeated Start Set-Up
Time
t
HD(STA(MIN))
Minimum Hold Time (Repeated)
Start Condition
t
SU(STO(MIN))
Minimum Set-Up Time for Stop
Condition
t
SU(DAT(MIN))
Minimum Data Setup Time Input
T
HD(DAT(MIN))
Minimum Data Hold Time Input
T
HDDATO
T
OF
Data Hold Time Input Output
Data Output Fall Time
(Notes 7, 8)
l
Note 1.
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2.
All currents into pins are positive, all voltages are referenced to
GND unless otherwise specified.
Note 3.
I
SUPPLY
= I
SENSE+
+ I
SENSE–
. In most operating modes I
SUPPLY
is
flowing in SENSE
+
pin. Only during ADC conversions current is flowing in
SENSE
–
pin as well. Typically, I
SENSE–
= V
SENSE–
/150k during ADC voltage
conversion and I
SENSE–
= 20µA during ADC current conversion.
Note 4.
The equivalent charge of an LSB in the accumulated charge
register depends on the value of R
SENSE
and the setting of the internal
prescaling factor M:
q
LSB
= 0.340mAh
• (50mΩ/R
SENSE
) • (M/4096):
See Choosing R
SENSE
and Choosing Coulomb Counter Prescaler M section
for more information. 1mAh = 3.6C (Coulombs)
Note 5.
Deviation of q
LSB
from its nominal value.
Note 6.
The quantization step of the 14-bit ADC in voltage mode, 12-bit
ADC in current mode and 11-bit ADC in temperature mode is not the same
as the LSB of the respective combined 16-bit registers. See the Voltage,
Current and Temperature Registers section for more information.
Note 7.
C
B
= Capacitance of one bus line in pF (10pF ≤ C
B
≤ 400pF).
Note 8.
Guaranteed by design, not subject to test.
Note 9.
See "Effect of Differential Offset Voltage on Total Charge Error”
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