LTC2945
Wide Range
I
2
C Power Monitor
FEATURES
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DESCRIPTION
The
LTC
®
2945
is a rail-to-rail system monitor that mea-
sures current, voltage, and power. It features an operating
range of 2.7V to 80V and includes a shunt regulator for
supplies above 80V to allow flexibility in the selection of
input supply. The current measurement range of 0V to
80V is independent of the input supply. An onboard 0.75%
accurate 12-bit ADC measures load current, input voltage
and an auxiliary external voltage. A 24-bit power value is
generated by digitally multiplying the measured 12-bit load
current and input voltage data. Minimum and maximum
values are stored and an overrange alert with program-
mable thresholds minimizes the need for software polling.
Data is reported via a standard I
2
C interface. Shutdown
mode reduces power consumption to 20µA.
The LTC2945 I
2
C interface includes separate data input
and output pins for use with standard or opto-isolated I
2
C
connections. The LTC2945-1 has an inverted data output
for use with inverting opto-isolator configurations.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Rail-to-Rail Input Range: 0V to 80V
Wide Input Supply Range: 2.7V to 80V
Shunt Regulator for Supplies >80V
Δ∑ ADC with less than ±0.75% Total Unadjusted Error
12-Bit Resolution for Current and Voltages
Internal Multiplier Calculates 24-Bit Power Value
Stores Minimum and Maximum Values
Alerts When Limits Exceeded
Additional ADC Input Monitors an External Voltage
Continuous Scan and Snapshot Modes
Shutdown Mode with I
Q
< 80µA
Split SDA for Opto-Isolation
Available in 12-Lead 3mm
×
3mm QFN and MSOP
Packages
APPLICATIONS
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Telecom Infrastructure
Industrial
Automotive
Consumer
TYPICAL APPLICATION
Wide Range Power Monitor with Onboard ADC and I
2
C
V
IN
4V TO 80V
0.02
TO
LOAD
0.3
0.2
0.1
0.0
–0.1
–0.2
–0.3
ADC Differential
Nonlinearity (ADIN)
0.3
0.2
0.1
0.0
–0.1
–0.2
–0.3
ADC Integral Nonlinearity
(ADIN)
SENSE
+
V
DD
0.1µF
NINE I
2
C
ADDRESSES
SENSE
–
ADC DNL (LSB)
ALERT
SCL
SDAI
SDAO
ADIN
I
2
C
INTERFACE
MEASURED
VOLTAGE
INTV
CC
ADR1
ADR0
LTC2945
GND
2945 TA01
0
ADC INL (LSB)
1024
2048
CODE
3072
4096
2945 TA01a
0
1024
2048
CODE
3072
4096
2945 TA01b
2945fb
For more information
www.linear.com/LTC2945
1
LTC2945
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
V
DD
Voltage.............................................. –0.3V to 100V
SENSE
+
Voltage ...........................................–1V to 100V
SENSE
–
Voltage .....–1V or SENSE
+
– 1V to SENSE
+
+ 1V
INTV
CC
Voltage (Note 3) ........................... –0.3V to 5.9V
ADR1, ADR0, ADIN,
ALERT,
SDAO,
SDAO
Voltage ......................................................... –0.3V to 7V
INTV
CC
Clamp Current ...........................................35mA
SCL, SDAI Voltages (Note 4) ..................... –0.3V to 5.9V
SCL, SDAI Clamp Current ........................................5mA
Operating Temperature Range
LTC2945C ................................................ 0°C to 70°C
LTC2945I .............................................–40°C to 85°C
LTC2945H .......................................... –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10sec)
MS Package Only .............................................. 300°C
PIN CONFIGURATION
LTC2945
TOP VIEW
SENSE
–
SENSE
+
V
DD
TOP VIEW
9
13
8
7
4
ADIN
5
GND
6
SCL
ALERT
SDAO
SDAI
V
DD
INTV
CC
ADR1
ADR0
ADIN
GND
1
2
3
4
5
6
12
11
10
9
8
7
SENSE
+
SENSE
–
ALERT
SDAO
SDAI
SCL
12 11 10
INTV
CC
1
ADR1 2
ADR0 3
UD PACKAGE
12-LEAD (3mm
×
3mm) PLASTIC QFN
T
JMAX
= 125°C,
q
JA
= 58.7°C/W
EXPOSED PAD (Pin 13) PCB GND CONNECTION OPTIONAL
LTC2945-1
TOP VIEW
SENSE
–
SENSE
+
V
DD
MS PACKAGE
12-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
q
JA
= 135°C/W
12 11 10
INTV
CC
1
ADR1 2
ADR0 3
4
ADIN
5
GND
6
SCL
13
9
8
7
ALERT
SDAO
SDAI
V
DD
INTV
CC
ADR1
ADR0
ADIN
GND
1
2
3
4
5
6
TOP VIEW
12
11
10
9
8
7
SENSE
+
SENSE
–
ALERT
SDAO
SDAI
SCL
UD PACKAGE
12-LEAD (3mm
×
3mm) PLASTIC QFN
T
JMAX
= 125°C,
q
JA
= 58.7°C/W
EXPOSED PAD (Pin 13) PCB GND CONNECTION OPTIONAL
MS PACKAGE
12-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
q
JA
= 135°C/W
2945fb
2
For more information
www.linear.com/LTC2945
LTC2945
ORDER INFORMATION
LEAD FREE FINISH
LTC2945CUD#PBF
LTC2945IUD#PBF
LTC2945HUD#PBF
LTC2945CUD-1#PBF
LTC2945IUD-1#PBF
LTC2945HUD-1#PBF
LTC2945CMS#PBF
LTC2945IMS#PBF
LTC2945HMS#PBF
LTC2945CMS-1#PBF
LTC2945IMS-1#PBF
LTC2945HMS-1#PBF
TAPE AND REEL
LTC2945CUD#TRPBF
LTC2945IUD#TRPBF
LTC2945HUD#TRPBF
LTC2945CUD-1#TRPBF
LTC2945IUD-1#TRPBF
LTC2945HUD-1#TRPBF
LTC2945CMS#TRPBF
LTC2945IMS#TRPBF
LTC2945HMS#TRPBF
LTC2945CMS-1#TRPBF
LTC2945IMS-1#TRPBF
LTC2945HMS-1#TRPBF
PART MARKING
LFWK
LFWK
LFWK
LFYX
LFYX
LFYX
2945
2945
2945
29451
29451
29451
PACKAGE DESCRIPTION
12-Lead (3mm
×
3mm) Plastic QFN
12-Lead (3mm
×
3mm) Plastic QFN
12-Lead (3mm
×
3mm) Plastic QFN
12-Lead (3mm
×
3mm) Plastic QFN
12-Lead (3mm
×
3mm) Plastic QFN
12-Lead (3mm
×
3mm) Plastic QFN
12-Lead Plastic MSOP
12-Lead Plastic MSOP
12-Lead Plastic MSOP
12-Lead Plastic MSOP
12-Lead Plastic MSOP
12-Lead Plastic MSOP
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
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/
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
DD
is from 4V to 80V unless otherwise noted. (Note 2)
SYMBOL
SUPPLIES
V
DD
V
INTVCC
I
DD
I
CC
I
CCSRC
V
CC
ΔV
CC
V
CCZ
ΔV
CCZ
V
CC(UVL)
V
DD(UVL)
V
DDI2C(RST)
V
CCI2C(RST)
V
DD
Supply Voltage Range
INTV
CC
Supply Voltage Range
V
DD
Supply Current
INTV
CC
Supply Current
INTV
CC
Linear Regulator Output Current
INTV
CC
Linear Regulator Voltage
INTV
CC
Linear Regulator Load Regulation
INTV
CC
Shunt Regulator Voltage
INTV
CC
Shunt Regulator Load Regulation
INTV
CC
Supply Undervoltage Lockout
V
DD
Supply Undervoltage Lockout
V
DD
I
2
C Logic Reset
INTV
CC
I
2
C Logic Reset
V
DD
= 48V, INTV
CC
Open
Shutdown
INTV
CC
= V
DD
= 5V
Shutdown, INTV
CC
= V
DD
= 5V
V
DD
= 7V
7V < V
DD
< 80V, I
LOAD
= 1mA (C-, I-Grade)
7V < V
DD
< 80V, I
LOAD
= 1mA (H-Grade)
7V < V
DD
< 80V, I
LOAD
= 1mA to 10mA
V
DD
= 48V, I
CC
= 1mA
V
DD
= 48V, I
CC
= 1mA to 35mA
INTV
CC
Rising, V
DD
= INTV
CC
V
DD
Rising, INTV
CC
Open (C-, I-Grade)
V
DD
Rising, INTV
CC
Open (H-Grade)
V
DD
Falling, INTV
CC
Open (C-, I-Grade)
V
DD
Falling, INTV
CC
Open (H-Grade)
INTV
CC
Falling, V
DD
= INTV
CC
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ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
MIN
4
2.7
TYP
MAX
80
5.9
UNITS
V
V
mA
µA
mA
µA
mA
V
V
mV
V
mV
V
V
V
V
V
V
0.8
40
0.6
20
4.5
4.5
5.9
2.2
2.9
2.6
2
1.7
1.5
5
5
100
6.3
2.6
3.2
3.2
2.5
2.5
1.8
1.2
70
0.9
80
–10
5.5
5.7
200
6.7
250
2.69
3.5
3.5
2945fb
For more information
www.linear.com/LTC2945
3
LTC2945
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
DD
is from 4V to 80V unless otherwise noted. (Note 2)
SYMBOL
SENSE INPUTS
V
CM
I
SENSE
+
(HI)
I
SENSE
–
(HI)
I
SENSE
+
(LO)
I
SENSE
–
(LO)
ADC
RES
V
FS
LSB
Resolution (No missing codes)
Full-Scale Voltage
(Note 5)
ΔSENSE (Note 7)
V
IN
ADIN
ΔSENSE
V
IN
ADIN
ΔSENSE
V
IN
ADIN
ΔSENSE
V
IN
ADIN
ΔSENSE
V
IN
ADIN
ΔSENSE
V
IN
ADIN
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ELECTRICAL CHARACTERISTICS
PARAMETER
SENSE
+
, SENSE
–
Common Mode Voltage
48V SENSE
+
Input Current
48V SENSE
–
Input Current
0V SENSE
+
Source Current
0V SENSE
–
Source Current
CONDITIONS
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MIN
0
TYP
MAX
80
UNITS
V
µA
µA
µA
µA
µA
µA
µA
µA
Bits
SENSE
+
, SENSE
–
, V
DD
= 48V
Shutdown
SENSE
+
, SENSE
–
, V
DD
= 48V
Shutdown
SENSE
+
, SENSE
–
= 0V V
DD
= 48V
Shutdown
SENSE
+
, SENSE
–
= 0V, V
DD
= 48V
Shutdown
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100
150
2
20
1
–10
–2
–5
±1
12
101.7
101.7
2.033
102.4
102.4
2.048
25
25
0.5
±0.75
±0.75
±0.75
±3.1
±1.5
±1.1
±3
±2
±2
1.2
0.3
10
6
60
30
3
7.5
66
33
10
±1
2.1
0.3
2.4
0.6
2.7
0.9
±13
±7
0.15
0
1.5
5.9
1.9
6.4
0
0.4
±1
2.2
6.9
±1
9
72
36
103.1
103.1
2.063
mV
V
V
µV
mV
mV
%
%
%
LSB
LSB
LSB
LSB
LSB
LSB
µV
RMS
mV
RMS
µV
RMS
Hz
ms
ms
MΩ
µA
V
V
µA
µA
V
µA
V
V
µA
LSB Step Size
TUE
Total Unadjusted Error (Note 6)
V
OS
INL
Offset Error
Integral Nonlinearity
s
T
f
CONV
t
CONV
R
ADIN
I
ADIN
V
ADR(H)
V
ADR(L)
I
ADR(IN)
I
ADR(IN,Z)
V
OD(OL)
I
SDA,SCL(IN)
V
SDA,SCL(TH)
V
SDA,SCL(CL)
I
ALERT(IN)
Transition Noise (Note 5)
Conversion Rate (Continuous Mode)
Conversion Time (Snapshot Mode)
ADIN Pin Input Resistance
ADIN Pin Input Current
ADR0, ADR1 Input High Threshold
ADR0, ADR1 Input Low Threshold
ADR0, ADR1 Input Current
Allowable Leakage When Open
SDAO,
SDAO, ALERT
Output Low Voltage
SDAI, SDAO,
SDAO,
SCL Input Current
SDAI, SCL Input Threshold
SDAI, SCL Clamp Voltage
ALERT
Input Current
I
SDAI
, I
SCL
= 3mA
ALERT
= 5V
I
SDAO
, I
SDAO
, I
ALERT
= 8mA
SDAI, SDAO,
SDAO,
SCL = 5V
ADR0, ADR1 = 0V, 3V
ΔSENSE
V
IN
, ADIN
V
DD
= 48V, ADIN = 3V
V
DD
= 48V, ADIN = 3V
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I
2
C INTERFACE (V
DD
= 48V)
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2945fb
4
For more information
www.linear.com/LTC2945
LTC2945
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
DD
is from 4V to 80V unless otherwise noted. (Note 2)
SYMBOL
f
SCL(MAX)
t
LOW
t
HIGH
t
BUF(MIN)
t
HD,STA(MIN)
t
SU,STA(MIN)
t
SU,STO(MIN)
t
HD,DATI(MIN)
t
HD,DATO(MIN)
t
SU,DAT(MIN)
t
SP(MAX)
t
RST
C
X
PARAMETER
Maximum SCL Clock Frequency
Minimum SCL Low Period
Minimum SCL High Period
Minimum Bus Free Time Between Stop/Start
Condition
Minimum Hold Time After (Repeated) Start
Condition
Minimum Repeated Start Condition Set-Up
Time
Minimum Stop Condition Set-Up Time
Minimum Data Hold Time Input
Minimum Data Hold Time Output
Minimum Data Set-Up Time
Maximum Suppressed Spike Pulse Width
Stuck Bus Reset Time
SCL, SDAI Input Capacitance (Note 5)
SCL or SDAI Held Low
50
25
300
CONDITIONS
MIN
400
0.65
50
0.12
140
30
30
–100
600
30
110
33
5
10
1.3
600
1.3
600
600
600
0
900
100
250
TYP
MAX
UNITS
kHz
µs
ns
µs
ns
ns
ns
ns
ns
ns
ns
ms
pF
I
2
C INTERFACE TIMING
ELECTRICAL CHARACTERISTICS
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
ground, unless otherwise noted.
Note 3:
An internal shunt regulator limits the INTV
CC
pin to a minimum of
5.9V. Driving this pin to voltages beyond 5.9V may damage the part. This
pin can be safely tied to higher voltages through a resistor that limits the
current below 35mA.
Note 4:
Internal clamps limit the SCL and SDAI pins to a minimum of 5.9V.
Driving these pins to voltages beyond the clamp may damage the part. The
pins can be safely tied to higher voltages through resistors that limit the
current below 5mA.
Note 5:
Guaranteed by design and not subject to test.
Note 6:
(
ACTUAL CODE
−IDEAL
CODE
)
TUE
=
4096
×
100%
where IDEAL CODE is derived from a straight line passing through Code 0
at 0V and Theoretical Code of 4096 at V
FS
.
Note 7:
ΔSENSE is defined as V
SENSE
+ – V
SENSE
–
2945fb
For more information
www.linear.com/LTC2945
5
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