LT5554IUH#PBF [Linear]
LT5554 - Broadband Ultra Low Distortion 7-Bit Digitally Controlled VGA; Package: QFN; Pins: 32; Temperature Range: -40°C to 85°C;
| 型号： | LT5554IUH#PBF |
| 厂家： | 
Linear |
| 描述： | LT5554 - Broadband Ultra Low Distortion 7-Bit Digitally Controlled VGA; Package: QFN; Pins: 32; Temperature Range: -40°C to 85°C |
| 文件： | 总24页 (文件大小：325K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT2940
Power and Current Monitor
FEATURES
DESCRIPTION
The LT®2940 measures a high side current and a differ-
ential voltage, multiplies them and outputs a current
proportional to instantaneous power. Bidirectional high
side currents and bipolar voltage differences are correctly
handled by the four-quadrant multiplier and push-pull
output stage, which allows the LT2940 to indicate forward
and reverse power flow.
n
Four-Quadrant Power Measurement
n
±±5 Power Measurement Aꢀꢀuraꢀc
n
4V to 80V High Side Sense, 100V Max
n
Current Mode Power and Current Outputs
n
Output Bandwidth Exꢀeeds ±00kHz
n
±ꢁ5 Current Measurement Aꢀꢀuraꢀc
n
6V to 80V Supply Range, 100V Max
n
Inverting and Noninverting Open-Collector
An integrated comparator with inverting and noninvert-
ing open-collector outputs makes the LT2940 a complete
power level monitor. In addition, an output current pro-
portional to the sensed high side current allows current
monitoring. The current mode outputs make scaling,
filtering and time integration as simple as selecting ex-
ternal resistors and/or capacitors.
Comparator Outputs
n
Available in 12-Pin DFN (3mm × 3mm) and 12-Lead
MSOP Packages
APPLICATIONS
n
Board Level Power and Current Monitoring
n
Line Card and Server Power Monitoring
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.
n
Power Sense Circuit Breaker
n
Power Control Loops
n
Power/Energy Meters
n
Battery Charger Metering
TYPICAL APPLICATION
Load Monitor Alarms Above 60W
Monitor Output Level and Load Power
I
LOAD
2.5
2.0
1.5
1.0
0.5
0
120
96
72
48
24
0
0A TO 10A
80V
6V TO 80V
30V
+
V
–
20mΩ
2W
15V
LOAD
LOAD
10V
LED ON
5V
1k
V
= 6V
LOAD
+
–
V
CC
I
I
LATCH
110k
+
CMPOUT
LED OFF
60W ALARM
V
LT2940
GND
LED ON WHEN
LOAD
CMPOUT
10.0k
P
> 60W
+
–
CMP
V
PMON
IMON
mV
W
mV
A
V
PMON
= P
• 20.75
LOAD
V
= I
• 100
IMON LOAD
0
2
4
6
8
(A)
10
12
14
24.9K
4.99k
I
LOAD
2940 TA01b
1
12
k
=
V
k = 20mΩ
I
P
LOAD
= V
• I
LOAD LOAD
2940 TA01a
2940f
1
LT2940
ABSOLUTE MAXIMUM RATINGS (Notes 1, 2)
+
–
–
V
, I , I , LATCH....................................–0.3V to 100V
Operating Temperature Range
CC
+
+
V , V , CMP .............................................–0.3V to 36V
LT2940C................................................... 0°C to 70°C
LT2940I................................................–40°C to 85°C
Storage Temperature Range...................–65°C to 150°C
Lead Temperature (Soldering, 10 sec)
+
–
Voltage Sense (V – V ) ......................................... 36V
+
–
Current Sense (I – I )............................................ 36V
PMON, IMON (Note 3) ...... –0.3V to V + 1V, Up to 16V
CC
CMPOUT, CMPOUT ....................................–0.3V to 36V
MSOP Package ................................................. 300°C
CMPOUT, CMPOUT DC Output Current ..................22mA
PIN CONFIGURATION
TOP VIEW
TOP VIEW
1
2
3
4
5
6
12
11
10
9
V
CC
CMPOUT
+
1
2
3
4
5
6
CMPOUT
12
11
10
9
8
7
V
CC
I
I
CMPOUT
+
CMPOUT
I
I
–
+
CMP
+
–
13
CMP
LATCH
PMON
IMON
GND
PMON
IMON
GND
LATCH
+
+
–
V
V
V
8
–
7
V
MS PACKAGE
12-LEAD PLASTIC MSOP
DD PACKAGE
12-LEAD (3mm s 3mm) PLASTIC DFN
T
= 125°C, θ = 135°C/W
T
= 125°C, θ = 43°C/W
JA
JMAX
JA
JMAX
EXPOSED PAD (PIN 13) PCB GND CONNECTION OPTIONAL
ORDER INFORMATION
LEAD FREE FINISH
LT2940CDD#PBF
LT2940IDD#PBF
LT2940CMS#PBF
LT2940IMS#PBF
TAPE AND REEL
PART MARKING*
LDPP
PACKAGE DESCRIPTION
12-Lead Plastic DFN
12-Lead Plastic DFN
12-Lead Plastic MSOP
12-Lead Plastic MSOP
TEMPERATURE RANGE
0°C to 70°C
LT2940CDD#TRPBF
LT2940IDD#TRPBF
LT2940CMS#TRPBF
LT2940IMS#TRPBF
LDPP
–40°C to 85°C
0°C to 70°C
2940
2940
–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/
2940f
2
LT2940
ELECTRICAL CHARACTERISTICS The l denotes the speꢀifiꢀations whiꢀh applc over the full operating
temperature range, otherwise speꢀifiꢀations are at TA = 2±°C. All speꢀifiꢀations applc at 6V ≤ VCC ≤ 80V, unless otherwise speꢀified.
SYMBOL
Supplc
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
l
l
V
Supply Voltage Operating Range
Supply Current
6
2
80
5
V
CC
I
CC
I
= +200μA, I = +200μA
IMON
3.5
mA
PMON
(Note 2)
l
l
V
Supply Undervoltage Latch Clear
Supply Undervoltage Hysteresis
V
V
Falling
Rising
2.3
20
2.5
75
2.7
V
CC(UVLC)
CC
CC
ΔV
100
mV
CC(HYST)
Voltage Sense
l
l
l
l
V
Voltage Sense Pin Operating Range
V
≤ 12V
–0.1
–0.1
–0.1
V – 3
CC
V
V
V
V
VSEN(OR)
CC
12V < V < 30V
9
CC
+
–
V Pin and V Pin
V
≥ 30V
18
CC
V
V
Voltage Sense Differential Input Voltage Range V < 11V
(Note 5)
(V – 3)
CC
CC
–
l
l
V = V
V
+
– V
V
V
≥ 11V
≥ 12V
8
9
V
V
V
V
CC
CC
V
V(CL)
Voltage Sense Differential Clipping Limit
(Note 5)
l
l
I
Voltage Sense Input Bias Current
–300
–100
50
100
150
nA
nA
VSEN
+
–
V Pin and V Pin
–
ΔI
Voltage Sense Input Offset Current
V
+
= V
VSEN
V V
–
ΔI
VSEN
= I
+
– I
V V
Current Sense
l
l
V
Current Sense Pin Operating Range
4
80
V
ISEN(OR)
+
–
I Pin and I Pin
V
Current Sense Differential Input Voltage
200
mV
I
Range (Note 6)
–
V = V – V
+
I
I I
l
l
l
V
Current Sense Differential Clipping Limit
(Note 6)
225
75
mV
μA
nA
I(CL)
I
Current Sense Input Bias Current
100
200
125
800
ISEN
+
–
I Pin and I Pin
–
ΔI
Current Sense Input Offset Current
V = V
+
ISEN
I I
–
ΔI
ISEN
= I – I
+
I I
Power Monitor (Note 2)
l
l
I
Power Monitor Output Current Operating
Range
200
900
μA
μA
PMON(OR)
I
Power Monitor Output Current Capability
V
V
V
≥ 12V, V ≥ 0V, and
PMON
1200
–1200
–1200
PMON(CAPA)
CC
V
V
= –9V, V = –225mV, or
I
= 9V, V = 225mV
I
l
l
V
V
V
≥ 12V, V
≥ 0.5V, and
PMON
–240
–800
μA
μA
CC
= –9V, V = 225mV, or
V
V
I
= 9V, V = –225mV
I
V
V
V
≥ 12V, V
≥ 4V, and
PMON
CC
= –9V, V = 225mV, or
V
V
I
= 9V, V = –225mV
I
2940f
3
LT2940
ELECTRICAL CHARACTERISTICS The l denotes the speꢀifiꢀations whiꢀh applc over the full operating
temperature range, otherwise speꢀifiꢀations are at TA = 2±°C. All speꢀifiꢀations applc at 6V ≤ VCC ≤ 80V, unless otherwise speꢀified.
SYMBOL
PARAMETER
CONDITIONS
≤ 12V, I
MIN
0
TYP
MAX
– 4.5
UNITS
V
l
l
l
l
l
l
V
PMON
Power Monitor Output Compliance Voltage
V
≥ 0μA
V
V
CC
PMON
CC
12V < V < 30V, I
≥ 0μA
< 0μA
0
7.5
12
V
CC
PMON
V
CC
V
CC
≥ 30V, I
≤ 12V, I
≥ 0μA
0
V
PMON
PMON
< 0μA
0.5
0.5
0.5
– 4.5
V
CC
12V < V < 30V, I
7.5
12
5
V
CC
PMON
V
≥ 30V, I
< 0μA
V
CC
PMON
2
E
Power Monitor Output Total Error (Note 4)
|V • V | ≤ 0.4V
2
%FS
%FS
%FS
%FS
%FS
PMON
V
I
2
|V • V | ≤ 0.4V , 25°C < T ≤ 85°C
2.5
2.5
3.5
5
7
V
I
A
2
l
l
l
|V • V | ≤ 0.4V , LT2940C
9
V
I
2
|V • V | ≤ 0.4V , LT2940I
12
15
V
I
Quadrants I and III of Shaded Region
in Figure 4
2
2
l
l
l
l
K
Power Monitor Scaling Coefficient
= K • V • V
|V • V | = 0.4V
485
500
40
2
515
100
6
μA/V
PMON
V
I
I
PMON
PMON
V
I
V
Power Monitor Voltage Sense Input-Referred
Offset Voltage
V
= 0V
V
mV
mV
V(OSP)
V
I(OSP)
Power Monitor Current Sense Input-Referred V = 0mV
Offset Voltage
I
–
I
Power Monitor Output Offset Current
Power Monitor Output Bandwidth
V
R
= 0V, V = 0mV
6
15
μA
PMON(OS)
V
I
BW
= 2k
0.5
MHz
PMON
PMON
Current Monitor (Note 2)
l
I
Current Monitor Output Current Operating
Range
200
μA
IMON(FS)
l
l
l
l
l
l
V
Current Monitor Output Compliance Voltage
V
≤ 12V, I
≥ 0μA
0
0
V
V
– 4.5
CC
V
V
IMON
CC
IMON
12V < V < 30V, I
≥ 0μA
< 0μA
7.5
12
CC
IMON
V
V
≥ 30V, I
≤ 12V, I
≥ 0μA
< 0μA
0
V
CC
CC
IMON
IMON
0.5
0.5
0.5
– 4.5
V
CC
12V < V < 30V, I
7.5
12
3
V
CC
PMON
V
≥ 30V, I
< 0μA
PMON
V
CC
E
Current Monitor Output Total Error (Note 4)
|V | ≤ 200mV, 25°C ≤ T ≤ 85°C
1.5
2
%FS
%FS
%FS
%FS
μA/V
mV
IMON
I
A
l
l
l
l
l
|V | ≤ 200mV, LT2940C
3.5
4
I
|V | ≤ 200mV, LT2940I
2
I
200mV < |V | ≤ 225mV
2.5
1000
2.5
5
I
G
Current Monitor Scaling, I
= G
• V
V = 200mV
975
1025
7
IMON
IMON
IMON
I
I
V
Current Monitor Current Sense Input-Referred
Offset Voltage
I(OSI)
BW
Current Monitor Output Bandwidth
R
= 2k
1
MHz
IMON
IMON
+
Comparator
l
l
l
l
V
Comparator Threshold Voltage
Comparator Threshold Hysteresis
Comparator Input Bias Current
CMPOUT Output Low Voltage
CMP Rising
1.222
–15
1.240
–35
100
0.2
1.258
–60
300
0.4
V
mV
nA
CMP(TH)
+
ΔV
CMP Falling
CMP(HYST)
CMP(BIAS)
I
I
1V ≤ V
+ ≤ 1.5V
CMP
+
CMP High, I
= 3mA
V
CMPOUT(OL)
CMPOUT
2940f
4
LT2940
ELECTRICAL CHARACTERISTICS The l denotes the speꢀifiꢀations whiꢀh applc over the full operating
temperature range, otherwise speꢀifiꢀations are at TA = 2±°C. All speꢀifiꢀations applc at 6V ≤ VCC ≤ 80V, unless otherwise speꢀified.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
+
l
I
CMPOUT Leakage Current
CMP Low, V = 36V,
0.15
1
μA
CMPOUT(LK)
CC
0.4V ≤ V
≤ 36V
CMPOUT
+
l
l
I
I
CMPOUT Output Low Voltage
CMPOUT Leakage Current
CMP Low, I
= 3mA
CMPOUT
0.2
0.4
1
V
CMPOUT(OL)
CMPOUT(LK)
+
CMP High, V = 36V,
0.15
μA
CC
0.4V ≤ V
≤ 36V
CMPOUT
l
l
l
l
l
t
Comparator Propagation Delay
LATCH Input Low Voltage
LATCH Input Open Voltage
LATCH Input High Voltage
Output Pulling Down
0.7
0.8
1.5
2.2
2
μs
V
DLY
V
V
V
0.5
1.25
2.0
1.2
1.95
2.5
10
LATCH(IL)
LATCH(IO)
LATCH(IH)
LATCH(LK)
V
V
I
I
LATCH Input Allowable Leakage in
Open State
μA
l
l
LATCH Input Bias Current
V
V
= 0V
–11
11
–17
17
–23
23
μA
μA
LATCH(BIAS)
LATCH
= 80V
LATCH
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, and all voltages are referenced
to GND unless otherwise noted. Current sourced by the PMON pin or the
IMON pin is defined as positive; current sunk as negative.
Note ꢁ: The LT2940 may safely drive its own PMON and IMON output
voltages above the absolute maximum ratings. Do not apply any external
source that drives the voltage above absolute maximum.
Note 4: Full-scale equals 200μA.
+
–
Note ±: V and V pin voltages must each fall within the voltage sense pin
operating range specification.
+
–
Note 6: I and I pin voltages must each fall within the current sense pin
operating range specification.
TYPICAL PERFORMANCE CHARACTERISTICS
PMON Output Current
PMON Total Error
vs Sense Input Voltages
vs Sense Input Voltages
PMON Error Band vs Temperature
800
600
400
200
0
3
2
4
3
ONE REPRESENTATIVE UNIT
–2V
V
I
= V + – V
–
V
CC
V
PMON
≥ 11V
V
V
V
V = V + – V –
= 0.5V
I
I
V
V
= 8V
V
V
= 80V
= 12V
CC
0V
2V
2
–4V
V
V
= –8V
–4V
1
1
CC
–8V ≤ V ≤ 8V
V
–2V
0V
0
0
–200mV ≤ V ≤ 200mV
I
2
|V • V | ≤ 0.4V
V
I
4V
–1
–2
–3
–4
–1
–2
–3
V
V
= 12V
= 80V
CC
2V
V
V
= 8V
–200
2
4V
8V
|V • V | ≤ 0.4V
V I
T
= 25°C
A
CC
–400
0
200
–200
–100
0
100
200
–200
–50
0
25
50
75 100 125
–25
V (mV)
I
V (mV)
I
TEMPERATURE (°C)
2940 G01
2940 G02
2949 G03
2940f
5
LT2940
TYPICAL PERFORMANCE CHARACTERISTICS
PMON Current
vs Power Sense Produꢀt
PMON and IMON Voltage
Complianꢀe
Supplc Current vs Supplc Voltage
1500
1000
500
300
200
100
0
3.6
3.4
3.2
3.0
2.8
2.6
2.4
V
V
≥ 15V
T = 25°C
A
CC
V
= 40 • V
I
I = 200μA
I
I
= 200μA
= 200μA
PMON
IMON
V
= 30V
CC
V
PMON
= 0V
V
= 6V
V
CC
= 12V
CC
I
I
= 0μA
= 0μA
0
PMON
IMON
V
PMON
= 0.5V
–500
–1000
–1500
V
= 4V
–100
–200
–300
PMON
I = –200μA
= 6V = 12V
I
I
= –200μA
= –200μA
PMON
IMON
V =
CC
30V
V
CC
V
CC
–4
–2
0
2
4
–5
0
5
10
15
20
0
20
40
60
80
100
2
V
• V (V )
OUTPUT VOLTAGE (V)
V
CC
(V)
V
I
2940 G04
2940 G05
2940 G06
IMON Current vs Current
Sense Voltage
IMON Total Error vs Current
Sense Voltage
IMON Error Band vs Temperature
300
200
100
0
3
2
2
1
V = V + – V –
I
I
I
ONE REPRESENTATIVE UNIT
–200mV ≤ V ≤ 200mV
I
–
V
= 12V
I
V
V
= 12V
= 80V
CC
1
V
= 12V
= 80V
CC
CC
V
IMON
= 0V
0
0
V
CC
–100
–200
–300
V
IMON
= 0.5V
–1
–2
–3
V
V
= 12V
= 80V
CC
OUTPUT CURRENT IS
APPROXIMATELY FLAT
TO ABSOLUTE MAXIMUM
VOLTAGE LIMITS
–1
CC
–2
–300
–100
0
100
200
300
–200
0
200
–200
–50
0
25
50
75 100 125
–25
V (mV)
I
V (mV)
I
TEMPERATURE (°C)
2940 G07
2940 G08
2949 G09
PMON Step Response
PMON Step Response
IMON Step Response
R
C
= 2k ON 2V BIAS
DC
R
C
= 2k ON 2V BIAS
R
C
= 2k ON 2V BIAS
PMON DC
IMON
L
PMON
L
DC
= 8pF
= 8pF
= 8pF
L
V
T
= 12V
V
T
= 12V
V
T
= 12V
= 25°C
CC
CC
CC
= 25°C
= 25°C
A
A
A
V = 200mV
I
V
I
=
2V
V = 200mV
I
V = 2V
V
V
V = 200mV
V
V
V
IMON
200mV/DIV
IMON
IMON
200mV/DIV
200mV/DIV
2940 G12
2940 G10
2940 G11
250ns/DIV
500ns/DIV
250ns/DIV
2940f
6
LT2940
TYPICAL PERFORMANCE CHARACTERISTICS
PMON Input Feedthrough
vs Frequenꢀc
Power Supplc Rejeꢀtion Ratio
vs Frequenꢀc
0
–10
–20
–30
–40
–50
–60
80
60
40
20
0
RELATIVE TO 1V
PK
R
= 5k ON 2V BIAS
DC
PMON
A
T
= 25°C
IMON
PMON
V
I
= 2V
PK
V
V = 0mV, dV = 0
V = 200mV
V
I
PK
V
= 0V, dI = 0
V
R
R
= 12V
CC
= 5k ON 2V BIAS
= 5k ON 2V BIAS
PMON
IMON
= 25°C
DC
DC
T
A
100
1k
10k
100k
1M
10M
100
1k
10k
100k
1M
10M
FREQUENCY (Hz)
2940 G14
FREQUENCY (Hz)
2940 G13
SEE TEST CIRCUITS FOR LOADING CONDITIONS
PMON Frequenꢀc Response
to Voltage Sense
PMON Frequenꢀc Response
to Current Sense
10
0
10
0
I-TO-V
AMP
RELATIVE TO DC GAIN
OUTPUT
RELATIVE TO DC GAIN
I-TO-V
AMP
OUTPUT
–10
–20
–30
–40
–10
–20
–30
–40
R
=
L
R
L
= 2k
L
2k
V
=
2V
V = 2V
V DC
V
PK
V = 200mV
V = 200mV
I
DC
I
PK
I
=
200μA (NOM)
I
=
200μA (NOM)
R = 5k
L
R
= 5k
PMON
A
PK
PMON
A
PK
T
= 25°C
T
= 25°C
100
1k
10k
100k
1M
10M
100
1k
10k
100k
1M
10M
FREQUENCY (Hz)
2940 G15
FREQUENCY (Hz)
2940 G16
SEE TEST CIRCUITS FOR LOADING CONDITIONS
SEE TEST CIRCUITS FOR LOADING CONDITIONS
IMON Frequenꢀc Response
to Current Sense
Open Colleꢀtor Current
vs Open Colleꢀtor Voltage
10
25
20
15
10
5
T
= 25°C
I-TO-V
AMP
A
OUTPUT PULLING LOW
RELATIVE TO DC GAIN
OUTPUT
0
–10
–20
–30
–40
V
= 80V
= 6V
CC
R
=
L
2k
V
CC
V = 200mV
I
PK
I
= 200μA (NOM)
PK
IMON
R
L
= 5k
T
= 25°C
A
0
100
1k
10k
FREQUENCY (Hz)
SEE TEST CIRCUITS FOR LOADING CONDITIONS
100k
1M
10M
2940 G17
0.1
10
OPEN COLLECTOR VOLTAGE (V)
100
1
2940 G18
2940f
7
LT2940
PIN FUNCTIONS
+
–
CMPOUT (Pin 1): Inverting Open-Collector Comparator
V , V (Pins 8, 7): Voltage Sense Inputs. The voltage
difference between these pins is the voltage input factor
to the power calculation multiplier. The difference may be
positive or negative, but both pin voltages must be at or
above GND – 100mV. The input differential voltage range
is 8V. Do not exceed 36V on either pin.
Output. When the LATCH pin’s state does not override the
+
comparator, CMPOUT pulls low when CMP > 1.24V. The
+
pull-down shuts off when CMP < 1.21V, or V < 2.5V or
CC
when the LATCH pin is low. CMPOUT may be pulled up to
36V maximum. Do not sink more than 22mA DC.
CMPOUT(Pin2):NoninvertingOpen-CollectorComparator
LATCH(Pin9):ComparatorModeInput. Conditionsatthis
three-state input pin control the comparator’s behavior.
When LATCH is open, the comparator’s outputs track its
input conditions (with hysteresis). When LATCH is held
Output. When the LATCH pin’s state does not override the
+
comparator, CMPOUT pulls low when CMP < 1.21V, or
V
< 2.5V, or when the LATCH pin is low. The pull-down
CC
+
+
shuts off when CMP > 1.24V. CMPOUT may be pulled up
above 2.5V, the comparator’s outputs latch when CMP
to 36V maximum. Do not sink more than 22mA DC.
exceeds1.24V(CMPOUTopen,CMPOUTpull-down).While
LATCH≤0.5VorV <2.5V,thecomparator’soutputsclear
+
CC
CMP (Pin ꢁ): Positive Comparator Input. The integrated
(CMPOUT pull-down, CMPOUT open) regardless of the
comparator resolves to high when the pin voltage exceeds
the 1.24V internal reference. The comparator input has
35mV of negative hysteresis, which makes its falling trip
+
CMP pin voltage. The LATCH pin high impedance input
state tolerates 10μA of leakage current. Bypass this pin
to GND to compensate for high dV/dt on adjacent pins.
Do not exceed 100V on this pin.
+
point approximately 1.21V. Do not exceed 36V. Tie CMP
to GND if unused.
+
–
I ,I (Pins11,10):CurrentSenseInputs.Thevoltagediffer-
enceatthesepinsrepresentsthecurrentinputfactortothe
power calculation multiplier and to the current scaler. The
differencemaybepositiveornegative,butbothpinvoltages
must be at least 4V and no more than 80V above GND,
PMON(Pin4):Proportional-to-PowerMonitorOutput.This
push-pull output sources or sinks a current proportional
to the product of the voltage sense and current sense
inputs. A resistor from PMON to GND creates a positive
voltage when the power product is positive. The full-scale
completely independent of the V voltage. Both pins sink
CC
output of 200μA is generated for a sense input product
approximately 100μA of bias current in addition to having
aneffective5kΩshuntbetweenthem.Theinputdifferential
voltage range is 200mV. Do not exceed 36V differ-
entially or 100V on either pin.
2
of 0.4V . Do not exceed V + 1V, up to 16V maximum.
CC
Tie PMON to GND if unused.
IMON (Pin ±): Proportional-to-Current Monitor Output.
This push-pull output sources or sinks a current propor-
tional to the voltage at the current sense input, which is
typically generated by a sense resistor that measures a
current. A resistor from IMON to GND creates a positive
voltage when the sensed current is positive. The full-scale
output of 200μA is generated by a current sense input
V
(Pin 12): Voltage Supply. The voltage supply operat-
CC
ing range is 6V to 80V. When operating with V > 15V,
CC
package heating can be reduced by adding an external
seriesdroppingresistor.BypassthispintoGNDtoimprove
supply rejection at frequencies above 10kHz as needed.
Do not exceed 100V on this pin.
of 200mV. Do not exceed V + 1V, up to 16V maximum.
CC
Tie IMON to GND if unused.
Exposed Pad (Pin 1ꢁ in DFN Paꢀkage): The exposed pad
may be left open or connected to device ground. For best
thermal performance, the exposed pad must be soldered
to the PCB.
GND (Pin 6): Device Ground.
2940f
8
LT2940
FUNCTIONAL BLOCK DIAGRAM
11 10
+
–
μA
V
I
I
G
K
= 1000
= 500
IMON
V
CC
12
6
+
IMON
5
GND
–
μA
PMON
2
V
+
V
+
8
7
PMON
CMPOUT
CMPOUT
4
1
–
V
–
4-QUADRANT
MULTIPLIER
+
CMP
+
–
3
9
D
Q
1.24V
UVLC
BGAP REF
AND UVLC
CLR
V
CC
LE
2
LATCHLO
LATCHHI
LATCH
THREE-STATE
DECODE
2940 BD
TEST CIRCUITS
Resistor on DC Bias
I-to-V Amplifier
12V
PMON
V
OUT
OR
IMON
R
C
499Ω
R
FB
R
PMON
OR
IMON
4.99k
L
V
OUT
2V
Q1
2N2369
2940 TC01
2V
2940 TC02
2940f
9
LT2940
APPLICATIONS INFORMATION
Introduꢀtion
Multiplier Operation
The LT2940 power and current monitor brings together
circuitsnecessarytomeasure, monitorandcontrolpower.
In circuits where voltage is constant, power is directly
proportional to current. The LT2940 enables power moni-
toring and control in applications where both the current
and the voltage may be variable due to supply voltage
uncertainty, component parametric changes, transient
conditions, time-varying signals, and so forth.
The LT2940 power and current monitor contains a four-
quadrant multiplier designed to measure the voltage and
current of a generator or load, and output signals propor-
tional to power and current. Figure 1 shows a signal path
block diagram. The operating ranges of the voltage sense
and current sense inputs are included. To simplify the
notation, the differential input voltages are defined as:
–
+
V = V – V
(1a)
(1b)
V
V
V
The LT2940’s four-quadrant multiplier calculates in-
stantaneous power from its voltage sense and current
sense inputs. Its output driver sources and sinks cur-
rent proportional to power (magnitude and direction),
which affords flexible voltage scaling, simple filtering
and, into a reference, bipolar signals. Its onboard
comparator is the final piece required for integrated
power monitoring. In addition, the LT2940 provides a
proportional-to-current output that allows for equally
straightforward scaling, filtering and monitoring of the
sensed current.
–
+
V = V – V
I
I
I
2
The full scale output of the multiplier core is 0.4V , which
the PMON output driver converts to current through a
scale factor of K
.
PMON
I
= K
• V • V
(2)
PMON
I
PMONµA V
KPMON = 500
V2
(3)
Thevoltageacrossthecurrentsenseinputpinsisconverted
to a current by the IMON output driver through the scale
factor of G
.
IMON
Please note: although standard convention defines cur-
rents as positive going into a pin (as is generally the case
in the Electrical Characteristics table), the opposite is
true of the PMON and IMON pins. Throughout this data
sheet the power and current monitor output currents
are defined positive coming out of PMON and IMON,
respectively.Adoptingthisconventionletspositivevoltage
differences at the current and voltage sense pins yield
positive currents sourced from PMON and IMON that
can be scaled to positive ground referenced voltages
with a resistor.
I
= G
• V
I
(4)
IMON
IMON
µA
V
GIMON = 1000
(5)
Both the PMON and IMON outputs reach full-scale at
200μA.
The headroom and compliance limits for the input and
output pins are summarized in Table 1 for easy reference.
+
It is important to note that the current sense inputs, I
–
and I , operate over a 4V to 80V range completely inde-
pendent of the LT2940’s supply pin, V . Note also that
CC
the inputs accept signals of either polarity, and that the
–
V = V + – V
I
I
I
200mV (MAX)
11 10
μA
V
LT2940
IMON
+
–
G
2
= 1000
I
I
IMON
+
–
200μA
FULL-SCALE
5
4
μA
V
K
PMON
= 500
2
+
–
V
• V = 0.4V FULL-SCALE
V
V
V
I
+
8
7
–
= V + – V
V V
8V (MAX)
V
V
PMON
200μA
FULL-SCALE
–
2940 F01
Figure 1. LT2940 Signal Path Diagram
2940f
10
LT2940
APPLICATIONS INFORMATION
Table 1. LT2940 Essential Operating Parameters to Aꢀhieve Speꢀified Aꢀꢀuraꢀc (VCC Operating Range = 6V to 80V)
SENSE
INPUT
PINS
INPUT
OPERATING
RANGE
SCALING
TO
OUTPUT
MONITOR
OUTPUT
PARA-
METER
PIN VOLTAGE
LIMIT
OUTPUT OPERATING
OUTPUT
VOLTAGE COMPLIANCE
PINS
RANGE
+
–
Voltage
V , V
0V to V – 3V at V ≤ 12V
V = 8V
V
-
-
-
-
CC
CC
0V TO 9V at 12V < V < 30V
CC
0V to 18V at V ≥ 30V
CC
+
–
Current
Power
I , I
4V to 80V*
V = 200mV
G
=
IMON
I =
IMON
Sourcing:
I
IMON
1000μA/V
200μA
0V to V – 4.5V at V ≤ 7.5V
CC CC
+
–
–
2
0V to 7.5V at 12V < V < 30V
V , V ,
See Above Limits
V • V = 0.4V
K
=
PMON
I
=
CC
V
I
PMON
PMON
+
2
I , I
500μA/V
200μA
0V to 12V at V ≥ 30V
CC
Sinking:
As Above, Except Minimum is 0.5V
* The current sense range is completely independent of the supply voltage.
PMONandIMONoutputsarecapableofindicatingforward
and reverse flow of power and current, provided they are
advantageously biased.
Essential Design Equations
Afewequationsareneededtocalculateinputscalingfactors
and achieve a desired output. Consider the basic applica-
tion in Figure 3, where the power P is to be measured
2
The multiplier core full-scale product of 0.4V may
IN
be reached over a range of voltage and current inputs,
as shown in Figure 2. For example, voltage sense and
current sense combinations of 8V and 50mV, 4V and
as the product of voltage V and current I :
IN
IN
P = V • I
(6)
IN
IN IN
2
TheactualmeasuredquantitiesV andI arescaledtobe
100mV, and 2V and 200mV each multiply to 0.4V , and
IN
IN
level-compatiblewiththeLT2940. Inthisbasicapplication,
thus produce 200μA at PMON. This arrangement allows
the core to operate at full-scale, and therefore at best ac-
curacy, over a 4:1 range of current and voltage, a readily
appreciated feature when monitoring power in variable
supply applications.
a simple resistive voltage divider scales V , and a sense
IN
resistor scales I .
IN
V = V • k
(7a)
V
IN
V
R1
R1+ R2
kV =
200
(7b)
(8a)
(8b)
I
PMON
= 200μA
V = I • k
I
IN
I
100
50
k = R
100μA
I
SENSE
50μA
The PMON output current is given by:
25μA
12.5μA
I
= K
• V • k • I • k
(9a)
PMON
PMON
IN
V
IN
I
25
or
I
= P • K
• k • k
V I
(9b)
PMON
IN
PMON
12.5
0.5
4
1
2
8
The output current may be positive (sourcing) or
negative (sinking) depending on the signs of V , k ,
–
= V + – V (V)
V V
V
V
2940 F02
IN
V
Figure 2. PMON Output Current as a Funꢀtion
of Sense Input Voltages
I , and k . Provided that the magnitudes of V and V
IN
I
V
I
do not exceed 8V and 200mV as shown in Figure 2, at
2940f
11
LT2940
APPLICATIONS INFORMATION
I
IN
P
V
= V • I
IN IN
IN
IN
R
SENSE
LOAD
11 10
+
LT2940
–
I
I
+
–
I
I
IMON
IMON
5
4
V
V
IMON
R1
R1 + R2
R1
R1 + R2
V
V
= V
•
m
m
k =
V
IN
R
R
IMON
R2
R1
V = I • R
I
k = R
I SENSE
IN
SENSE
+
–
V
V
+
–
8
7
PMON
PMON
PMON
PMON
2940 F03
Figure ꢁ. Basiꢀ Power Sensing Appliꢀation Showing Derivation of kV and kI
Aꢀꢀuraꢀc
the full-scale output current of 200μA, the achievable
full-scale power is:
The principal accuracies of the power and current monitor
outputs are characterized as absolute percentages of full-
scale output currents, using the nominal values of scaling
parameters. The total error of the I
typically 2%, and is defined as:
0.4V2
P
=
IN(FS)
kV • kI
(10)
output, E
, is
PMON
PMON
In some applications the PMON output is converted to a
voltage by a load resistor:
µA
V2
200µA
IPMON − 500
•(VV • V )
I
V
PMON
= I
• R
PMON
(11)
PMON
EPMON
=
• 100%
The complete end-to-end scaling is then given by:
= P • K • k • k • R
(17)
Contributorstothepoweroutputaccuracysuchasthescal-
ing(K ), theoutputoffset(I ), andthevoltage
V
(12)
PMON
IN
PMON
V
I
PMON
The current monitor output current at IMON is found by
combining Equations 4 and 8a:
PMON
PMON(OS)
and current sense input offsets (V
and V
), are
V(OSP)
I(OSP)
separately specified at key conditions and may be totaled
using the root sum-of-squares (RSS) method.
I
= I • G
• k
(13)
The output current may be positive (sourcing) or negative
(sinking) depending on the signs of I and k . Provided
IMON
IN
IMON
I
The total error of the I
output, E
, is typically
IMON
IMON
IN
I
1.5%, and is defined as:
that the magnitude of V does not exceed 200mV, at the
I
full-scale output current of 200μA the achievable full-
scale input current is:
μA
IIMON − 1000
• V
I
V
EIMON
=
• 100%
0.2V
kI
200μA
IIN(FS)
=
(18)
Contributors to the current output accuracy such as the
scaling(G )andthecurrentsenseinputoffset(V
(14)
If IMON current is converted to a voltage by a load resis-
tor, then:
)
I(OSI)
IMON
are separately specified at key conditions. Here again, use
the RSS method of totaling errors.
V
IMON
= I
• R
IMON
(15)
IMON
and the final end-to-end scaling is given by:
= I • G • k • R
V
(16)
IMON
IN
IMON
I
IMON
2940f
12
LT2940
APPLICATIONS INFORMATION
Multiplier Operating Regions
these regions. Inputs beyond those ranges, and out to the
absolute maximum ratings, are clipped internally.
The operating regions of the four-quadrant multiplier are
illustrated in Figure 4. Note that while Figure 2’s axes em-
ployedlogarithmic(octave)scalestoallowconstant-power
trajectories to be straight lines, Figure 4’s axes are linear
to better accommodate negative inputs. Constant-power
trajectories are thus arcs.
Range and Aꢀꢀuraꢀc Considerations
The LT2940’s performance and operating range may best
beexploitedbylettingthebroadapplicationcategorysteer
design direction.
Constant-power applications comprise power level alarm
circuits, whether tripping a circuit breaker, activating aux-
iliary circuits, or simply raising an alarm, and single-level
power servo loops. In such applications, accuracy is best
whenthefull-scaleoutputcurrentoftheLT2940represents
The heavy line circumscribing the guaranteed accuracy
region is limited both by the product of the sense inputs
(the curved edges) and by each sense input’s differential
range (the straight edges). The maximum product that
2
realizes the specified accuracy is V • V = 0.4V , and it
V
I
the power level of interest, i.e., the I
= 200μA load
produces nominally full-scale output currents of I
=
PMON
PMON
line (A) on Figure 5. Spans of voltage or current up to 4:1
naturally fit into the operating range of the LT2940.
200μA. At the same time, the voltage and current sense
inputs must not exceed 8V and 200mV, respectively.
In the shaded functional region, multiplying occurs but
the output current accuracy is derated as specified in the
Electrical Characteristics section.
Specialconstant-powerapplicationsarethesametypesof
circuits (level measuring, servos) with additional restric-
tions. If operating within the guaranteed accuracy region
of Figure 4 is important over voltage or current spans
wider than 4:1, let a PMON current less than full-scale
represent the power level. For example, the load line (B)
The shaded functional region offers headroom beyond the
guaranteed range in all quadrants, and excellent sourcing
2
currentoperationbeyondthestandard+0.4V senseprod-
uct limit in quadrants I and III. In quadrants II and IV, the
PMONcurrentislimitedbycompliancerange,soaccuracy
isnotspecified.SeetheElectricalCharacteristicsandTypi-
cal Performance Characteristics sections for operation in
of I
= 50μA in Figure 5 covers a span of 16:1 (V = 8V
PMON V
to 0.5V and V = 200mV to 12.5mV). Note that operating
I
along line (C), I
channel offsets reduce the value of doing so. Operating
= 25μA allows a span of 32:1, but the
PMON
300
400
II
I
CURRENT SENSE CLIPPING
I
CURRENT SENSE CLIPPED
250
200
150
100
50
LIMITED
BY PMON
200
100
50
COMPLIANCE
I
PMON
= 200μA
GUARANTEED
ACCURACY
100μA
(A)
0
50μA
–50
–100
–150
–200
–250
–300
25μA
(D)
(B)
LIMITED
BY PMON
COMPLIANCE
25
(C)
(V)
GUARANTEED
ACCURACY
CURRENT SENSE CLIPPED
III
IV
12.5
6
8
10 12
2940 F04
–12
–8
–6 –4 –2
0
2
4
–10
0.5
4
16
1
2
8
V
(V)
V
V
V
2940 F05
Figure 4. Multiplier Operating Regions vs Sense Input
Voltages. Aꢀꢀuraꢀc Is Derataed in Shaded Areas
Figure ±. Various Constant-Power Curves in Quadrant I
2940f
13
LT2940
APPLICATIONS INFORMATION
below full-scale also affords scaling flexibility. Line (D)
similar way, a capacitor load on IMON produces a volt-
age proportional to charge that can be used to create a
coulomb counter.
along I
= 100μA covers a 4:1 range like (A), but the
PMON
maximum V is 100mV, which reduces voltage drop and
I
dissipation in the sense resistor.
Comparator Funꢀtion
Variable power applications comprise power measuring,
whether battery charging, energy metering or motor
monitoring, variable load-boxes, and other circuits where
the significant metric is not a single value, and voltage
and current may be independent of each other. Design in
this case requires mapping the LT2940’s sense ranges to
cover the maximum voltage and the maximum current,
while considering whether the power represented is at,
The LT2940’s integrated comparator features an internal
fixed reference, complementary open-collector outputs
and configurable latching. A rising voltage at the CMP
+
pin is compared to the internal 1.24V threshold. 35mV
(typical)negativehysteresisprovidesglitchprotectionand
makes falling inputs trip the comparator at about 1.21V.
The comparator result drives the open-collector CMPOUT
and CMPOUT pins which, when pulling down, sink at
least 3mA down to 0.4V. See the Typical Performance
Characteristics for more information. Complementary
comparator outputs save external components in some
applications. The CMPOUT and CMPOUT pins may be
pulled up externally to 36V maximum.
above, or below full-scale I
. For example, setting it
PMON
at full-scale puts all values in the accurate range, setting
it above puts more accuracy in nominal power levels and
less accuracy in perhaps rarely encountered high levels,
and setting below might afford flexibility to lower dissipa-
tion in the current sense resistor.
Comparator Latꢀhing
Output Filtering and Integration
The LATCH pin controls the behavior of the comparator
outputs. When the LATCH pin is open, the comparator
output latch is transparent. Leakage currents up to 10μA
willnotchangethedecodedstateoftheLATCHpin.Internal
circuits weakly drive the pin to about 1.5V. Adding a 10nF
capacitor between LATCH and GND protects against high
dV/dt on adjacent pins and traces. Where more than 30V
and long inductive leads will be connected to LATCH,
damp potentially damaging ringing with a circuit like that
shown in Figure 6.
Lowpass filtering the output power or current signal is as
simple as adding a capacitor in parallel with the output
voltage scaling resistor at PMON or IMON. For example,
adding 1nF in parallel with the PMON load resistor on the
front page application creates a lowpass corner frequency
of approximately 6.4kHz on the power monitor voltage.
Loaded by only a capacitor, the PMON pin voltage is pro-
portional to the time-integral of power, which is energy.
The integrating watt-hour meter application shown on
the back page takes advantage of this convenience. In a
4V TO 80V
R9B
49.9k
R9A
20k
LONG
WIRE
+
–
I
I
RESET
LATCH
LT2940
C2
10nF
GND
2940 F06
Figure 6. LATCH Pin Proteꢀtive Damping
2940f
14
LT2940
APPLICATIONS INFORMATION
When the LATCH pin voltage exceeds 2.5V, the next high
result from the comparator also enables the comparator
latch.TheCMPOUTpingoesopen(high),andtheCMPOUT
pin sinks current (low) regardless of the changes to the
Thermal Considerations
Ifoperatingathighsupplyvoltages, donotignorepackage
dissipation. At 80V the dissipation could reach 400mW;
more if IMON or PMON current exceeds full-scale. Pack-
age thermal resistance is shown in the Pin Configuration
section. Package dissipation can be reduced by simply
+
CMP level until the latch is cleared. Latch activation is
+
level sensitive, not edge sensitive, so if CMP > 1.24V
when LATCH is brought above 2.5V, the comparator result
is high, and the latch is set immediately. The LATCH pin
adding a dropping resistor in series with the V pin, as
CC
showninFigure7.Theoperatingrangeofthecurrentsense
voltage may be taken safely to 80V regardless of the V
pin voltage.
+
–
CC
input pins I and I , which extends to 80V independent
+
of V , make this possible. The voltage ranges of the V ,
V , PMON and IMON pins are, however, limited by V .
CC
–
The latch is released and the comparator reports a low
CC
Consult Table 1 during design. Operating an open-col-
lector output pin with simultaneously large current and
large voltage bias also contributes to package heating and
must be avoided.
when LATCH ≤ 0.5V or when V < 2.3V regardless of the
CC
+
CMP pin voltage. In this state, the CMPOUT pin sinks
current (low), while the CMPOUT pin goes open (high).
As with latching, clearing is level-sensitive: comparator
outputsreacttotheinputsignalassoonasLATCH≥1.25V
and V > 2.7V.
CC
R
S
100V MAX
R12
0A TO 1.3A
LOAD
30V TO 80V
150mΩ
1/2W
5mA
3.9k
MAX
10% 1/8W
36V MAX
+
–
V
CC
I
I
R14
20k
R2
140k
LATCH
+
–
OVP
CMPOUT
V
V
LT2940
GND
R1
10.0k
CMPOUT
OVERPOWER (OVP) GOES HIGH
WHEN LOAD POWER > 40W
+
CMP
PMON
IMON
2940 F07
R3
6.19k
R4
13.7k
1
15
W
V
k
=
V
V
SCALE = 10
PMON
k = 150mΩ
I
40W FULL-SCALE
Figure 7. Supplc Resistor Reduꢀes Paꢀkage Heating bc Reduꢀing VCC Voltage
2940f
15
LT2940
TYPICAL APPLICATIONS
120W Supplc Monitor Inꢀludes ICC of LT2940
R
S
SUPPLY
30V TO 80V
100V (MAX)
0A TO 4A
LOAD
R12
50mΩ
1W
5mA
MAX
3.9k
1/8W
V
LOGIC
+
–
I
I
V
CC
R14
3.9k
R2
140k
LATCH
+
–
OVP
CMPOUT
CMPOUT
V
V
LT2940
GND
OVERPOWER (OVP) GOES HIGH
WHEN SUPPLY POWER > 120W
R1
10.0k
+
CMP
PMON
IMON
2940 TA02
R3
6.19k
R4
13.7k
W
V
1
15
k
=
V
SCALE = 30
V
PMON
120W FULL-SCALE
k = 50mΩ
I
12.±W PWM Heat Sourꢀe
R
S
200mΩ
3
INPUT
9.5V TO 14.5V
HEATSINK
Q = 12.5W
+
D1
1N5819
R7*
7Ω
C1
100μF
25V
Q3
2N3906
Q2
R6
TP0610
10k
+
–
V
I
I
CC
R2
LT2940
R5
10k
102k
+
–
LATCH
V
V
R1
25.5k
CMPOUT
CMPOUT
+
CMP
1
=
PMON GND IMON
k
V
5
200mΩ
3
z 1.7ms
k =
I
C4
4.7μF
R4
15.0k
t
OFF
Q1
FDS3672
2940 TA03
* SEVEN 50Ω, 5W RESISTORS IN PARALLEL.
MULTIPLE UNITS FACILITATE SPREADING HEAT.
2940f
16
LT2940
TYPICAL APPLICATIONS
ꢁ0W Linear Heat Sourꢀe
R
S
200mΩ
3
10V TO 40V
C1
100μF
50V
+
R3
10k
–
+
V
CC
I
I
R2
LT2940
C2
22nF
102k
+
–
D2
27V
V
V
R1
25.5k
+
V
R
PMON GND IMON
LM334
–
HEATSINK
Q = 30W
V
R4
R6
51Ω
680Ω
R5
6.8k
Q1
VN2222
D1
1N457
R7
R8
1k
3.3k
Q2
C3
470pF
TIP129
1
=
k
R9
10k
V
15
Q3
D44VH11
200mΩ
3
k =
I
R10
100Ω
10A/V
R11
100mΩ
2940 TA04
Wide Input Range 10W PWM Heat Sourꢀe
R
S
200mΩ
3
22.4V TO 72V
12V
C1
100μF
100V
+
R6
10k
+
–
Q3
2N3906
V
I
I
CC
D2
R2
1N4148
LT2940
D1
R5
10k
220k
R7
50Ω
25W
HEATSINK
Q = 10W
+
–
MUR1100E
12V
LATCH
V
V
R1
13k
Q2
BSS123
CMPOUT
CMPOUT
D3
1N4148
+
CMP
PMON GND IMON
C2
100nF
13
233
k
=
V
C4
4.7μF
R4
68k
200mΩ
3
k =
I
t
z 2ms
OFF
Q1
FDS3672
2940 TA05
2940f
17
LT2940
TYPICAL APPLICATIONS
8V to ꢁ2V, 8W Load
12V
R
S
200mΩ
8V TO 32V
12V
R3
2k
–
+
V
CC
I
I
C1
R2
100nF
30k
LT2940
R7
6.8Ω
10W
+
V
+
–
V
R
R1
10k
LM334
V
–
V
R5
6.8k
R4
680Ω
IMON GND PMON
D1
1N457
R6
10Ω
1
4
k
=
V
Q1
FDB3632
200μA/A
CURRENT
MONITOR
OUTPUT
k = 200mΩ
I
C4
100nF
2940 TA06
Adjustable 0W to 10W Load Box with UVLO and Thermal Shutdown
10V TO 40V
INPUT
R2
120k
R11
33Ω
12V
–
+
+
–
V
V
I
C11
10nF
12V
R1
D1
30k
R15
10k
R16
10k
1N4003
12V
C13
LT2940
0W TO 10W ADJ
10-TURN
10nF
200mV
+
–
V
CC
REF
R
R12
12k
S
R17
100Ω
R19
10k
200mΩ
–
OA
Q3
2N3906
LATCH
I
Q4
2N3906
R14
10Ω
+
1A/V
LT1635
Q1
FDB3632
CURRENT
MONITOR
OUTPUT
PMON
R13
10k
I
CONTROL
= 50mW/μA
R18
1k
CMPOUT
CMPOUT
+
1
5
k
=
V
IMON
GND CMP
R3B
91k
k = 200mΩ
I
R4
4.99k
UVLO
R3A
13k
Q2
2N3904*
TEMP R10
ADJ
500Ω
2940 TA07
*THERMAL SHUTDOWN; COUPLE TO Q1’s HEAT SINK
2940f
18
LT2940
TYPICAL APPLICATIONS
1-Cell Monitor with Bottom-Side Sense
12V
C1
100nF
R
R
S2
215Ω
S1
R12
1k
5%
215Ω
+
1W/V
LOAD
CHARGER
CYCLON
+
–
V
I
I
CC
R4 2.5W MAX
+
12.4k
+
–
PMON
V
V
R2
30k
1%
R1
121k
R5
4.99k
2V, 4.5AH
DT CELL*
LT2940
IMON
LT1635
D1
5.1V
1A/V
1A MAX
200mV
+
–
Q1
REF
2N3904
12V
+
–
Q2
2N3904
OA
GND
2940 TA08
R9
200Ω
1%
R6
1k
1%
R7
200Ω
1%
R8
1k
1%
121
151
k
=
= 0.8
V
R
S3
200mΩ
k = 200mΩ
I
–
LOAD
–
*www.hawkerpowersource.com
(423) 238-5700
CHARGER
Motor Monitor with Cirꢀuit Breaker
R
S
25mΩ
2
12V
+
C10
100μF
25V
+
–
R2A
10k
1%
V
I
I
CC
MUR120
LT2940
+
–
RESET
LATCH
V
V
R3
10k
GE
R1
10k
1%
5BPA34KAA10B
12V, 8A
CMPOUT
CMPOUT
PM FIELD
R2B
10k
1%
+
CMP
IMON GND PMON
V
V
PMON
IMON
1
k
=
V
6.5A/V
100W/V
3
C5
R5
R4
4.99k
C4
100nF
25mΩ
2
33nF 12.4k
k =
I
OVERCURRENT TRIP = 8A
Q1
FDB3632
2940 TA09
2940f
19
LT2940
TYPICAL APPLICATIONS
28V Power to Frequenꢀc Converter
R
S
200mΩ
28V INPUT
10V TO 40V
LOAD
C7
R2
1
5
k
=
120k
V
k = 200mΩ
R1A
30k
I
+
–
10nF
V
I
I
CC
R1B
30k
+
P
= 10W
V
MAX
–
LATCH
PMON
V
10W
1000Hz
f
=
OUT
LT2940
Q2
R5, 100k
D3
CMPOUT
V
CC
D4
R6, 100k
V
CMPOUT
CC
+
IMON GND CMP
Q3
D1
10V
LTC1440
+
–
IN
IN
+
+
–
V
C5
C6
100nF
V
CC
OUT
1μF
CENTRAL SEMI
CCLM2700
WIMA
HYST
REF
R9
1M
D2
= 1N4148
= 2N7000
OPTO-ISOLATOR
Q1
R4B
10k
–
V
GND
C4
2.2nF
R4A
240k
2940 TA10
Seꢀondarc-Side AC Cirꢀuit Breaker
T1
R2
120k
RESISTIVE
LOAD
12.6VAC
SECONDARY
R9
10k
C1A
220μF
25V
R1
30k
+
R
S
2X
FDS3732
200mΩ
3
Q4
Q1
V
Q2
D1
Q5
1N4001
R10
1k
+
–
R0
10Ω
CC
V
I
I
CC
LATCH
R11
10k
+
–
V
V
R6
1k
R7
1k
Q3
LT2940
R12
10k
D2
1N4001
D3
5.1V
CMPOUT
IMON
Q6
Q7
CMPOUT
+
CMP
GND PMON
C1B
220μF
25V
+
Q8
30
1
=
k
=
V
1A/V
PK
1.25A
TRIP
10W/V
150
5
= 2N3906
3A
30W
PK
200mΩ
3
R3
15k
R4
15k
k =
I
2940 TA11
2940f
20
LT2940
TYPICAL APPLICATIONS
AC Power and Current Monitor
T1
12.6VAC
SECONDARY
LOAD
R
S
C1A
220μF
25V
+
200mΩ
3
D1
1N4001
+
–
R3
10Ω
V
CC
I
I
+
–
C1B
220μF
25V
+
V
V
1
5
k
=
V
R1
LT2940
30k
200mΩ
3
k =
I
D2
D3
5.1V
R2
120k
1N4001
R6
1k
GND PMON
IMON
2940 TA12
R4
15k
R5
15k
10W/V
1A/V
3A
PK
30W
PK
Fullc Isolated AC Power and Current Monitor
7A
117V
“L”
1
T1
500
R
R
S2
S1
4.99Ω 4.99Ω
V
CC
V
CC
LOAD
R2A
200Ω
1%
+
–
R6
10k
15V
D2
D4
V
I
I
CC
1kW/V
853 W
C1
47μF
25V
+
R12
1k
V
R4
4.22k
PK
R1A
68.1Ω
• •
PMON
IMON
R5
4.99k
LT2940
GND
10.8V
117V
C2
100nF
R2B
200Ω
1%
R1B
68.1Ω
D1
5.1V
C12
100nF
T2
–
10A/V
V
10A
R7
10k
PK
D3
D5
117V
“N”
2940 TA13
ISOLATION
BARRIER
= 1N4148
T1 = MINNTRONIX 4810966R
T2 = 1168:108 POTENTIAL TRANSFORMER
68.1+ 68.1
108
1
kV
=
•
=
200 + 200 + 68.1+ 68.1 1168 42.58
4.99 + 4.99
10
kI =
=
500
501
IN CONSTRUCTING THIS CIRCUIT, THE CUSTOMER AGREES THAT, IN ADDITION TO THE TERMS AND CONDITIONS ON LINEAR TECHNOLOGY CORPORATION’S
(LTC) PURCHASE ORDER DOCUMENTS, LTC AND ANY OF ITS EMPLOYEES, AGENTS, REPRESENTATIVES AND CONTRACTORS SHALL HAVE NO LIABILITY,
UNDER CONTRACT, TORT OR ANY OTHER LEGAL OR EQUITABLE THEORY OF RECOVERY, TO CUSTOMER OR ANY OF ITS EMPLOYEES, AGENTS,
REPRESENTATIVES OR CONTRACTORS, FOR ANY PERSONAL INJURY, PROPERTY DAMAGE, OR ANY OTHER CLAIM (INCLUDING WITHOUT LIMITATION, FOR
CONSEQUENTIAL OR INCIDENTAL DAMAGES) RESULTING FROM ANY USE OF THIS CIRCUIT, UNDER ANY CONDITIONS, FORESEEABLE OR OTHERWISE.
CUSTOMER ALSO SHALL INDEMNIFY LTC AND ANY OF ITS EMPLOYEES, AGENTS, REPRESENTATIVES AND CONTRACTORS AGAINST ANY AND ALL LIABILITY,
DAMAGES, COSTS AND EXPENSES, INCLUDING ATTORNEY’S FEES, ARISING FROM ANY THIRD PARTY CLAIMS FOR PERSONAL INJURY, PROPERTY DAMAGE,
OR ANY OTHER CLAIM (INCLUDING WITHOUT LIMITATION, FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES) RESULTING FROM ANY USE OF THIS CIRCUIT,
UNDER ANY CONDITIONS, FORESEEABLE OR OTHERWISE.
2940f
21
LT2940
PACKAGE DESCRIPTION
DD Paꢀkage
12-Lead Plastiꢀ DFN (ꢁmm × ꢁmm)
(Reference LTC DWG # 05-08-1725 Rev A)
0.70 ±0.05
2.38 ±0.05
1.65 ±0.05
3.50 ±0.05
2.10 ±0.05
PACKAGE
OUTLINE
0.25 ± 0.05
0.45 BSC
2.25 REF
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
R = 0.115
0.40 ± 0.10
TYP
7
12
2.38 ±0.10
3.00 ±0.10
(4 SIDES)
1.65 ± 0.10
PIN 1 NOTCH
PIN 1
TOP MARK
R = 0.20 OR
0.25 × 45°
CHAMFER
(SEE NOTE 6)
6
1
0.23 ± 0.05
0.45 BSC
0.75 ±0.05
0.200 REF
2.25 REF
(DD12) DFN 0106 REV A
0.00 – 0.05
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD AND TIE BARS SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
2940f
22
LT2940
PACKAGE DESCRIPTION
MS Package
12-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1668 Rev Ø)
0.889 p 0.127
(.035 p .005)
5.23
(.206)
MIN
3.20 – 3.45
(.126 – .136)
4.039 p 0.102
(.159 p .004)
(NOTE 3)
0.65
(.0256)
BSC
0.42 p 0.038
(.0165 p .0015)
TYP
0.406 p 0.076
(.016 p .003)
REF
12 11 10 9 8 7
RECOMMENDED SOLDER PAD LAYOUT
DETAIL “A”
0o – 6o TYP
3.00 p 0.102
(.118 p .004)
(NOTE 4)
4.90 p 0.152
(.193 p .006)
0.254
(.010)
GAUGE PLANE
0.53 p 0.152
(.021 p .006)
1
2 3 4 5 6
0.86
(.034)
REF
1.10
(.043)
MAX
DETAIL “A”
0.18
(.007)
SEATING
PLANE
0.22 – 0.38
(.009 – .015)
TYP
0.1016 p 0.0508
(.004 p .002)
MSOP (MS12) 1107 REV Ø
0.650
(.0256)
BSC
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
2940f
23
LT2940
TYPICAL APPLICATION
Integrating Watt-Hour Meter
6V TO 80V
0A TO 2A
LOAD
5V
+
(80W MAX)
R
S
V
100mΩ
5V
IN
OUT
S1B
S2B
S3B
S4B
R2
215k
+
–
CB
R17
309k
C17
0.47μF
SHDN
C16
1μF
LT3014
+
–
CB
V
CC
I
I
ADJ
LTC6943
R16
GND
+
–
100k
S1A
S2A
S3A
S4A
C
V
V
R1
11.3k
+
–
C1
1μF
CA
CA
R15
+
V
24.9k
–
+
+
LT2940
CMP
SHA
C19
0.1μF
OSC
–
V
R14
20.0k
C18
0.1μF
LTC6702
CMPOUT
5V
–
+
R18
49.9k
LATCH
C20
0.1μF
R13
4.99k
V
DD
12V
1024 COUNTS
= 1 WATT-HOUR
Q
F
CMPOUT
GND
1
20
k
V
=
RESET
V
PMON GND
IMON
SS
CD4040
k = 100mΩ
I
C
T
Q1
2N7002
RESET
2.2μF
2940 TA14
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
2.7V to 12V Supply Voltage, 170ꢀA Supply Current
LTC1966
Precision Micropower Delta-Sigma RMS-to-DC
Converter
LTC1968
Precision Wide Bandwidth RMS-to-DC Converter 4.5V to 6V Supply Voltage, 500kHz 3dB-Error BW
LTC6101/
LTC6101HV
High Voltage, High Side, Precision Current Sense 4V to 60V/5V to 100V, Gain Configurable, SOT-23
Amplifiers
LTC6104
Bidirectional High Side, Precision Current Sense
Amplifier
4V to 60V, Gain Configurable, 8-Pin MSOP
2.7V to 36V, Gain Configurable, SOT23
Wide Operating Range: 7V to 80V
LTC6106
Low Cost, High Side Precision Current Sense
Amplifier
2
LTC4151
LTC4215
High Voltage I C Current and Voltage Monitor
2
Positive Hot Swap Controller with ADC and I C
8-Bit ADC Monitoring Current and Voltages, Supplies from 2.9V to 15V
LT4256-1/
LT4256-2
Positive 48V Hot Swap Controllers with Open-
Circuit Detect
Foldback Current Limiting, Open-Circuit and Overcurrent Fault Output,
Up to 80V Supply
LTC4260
Positive High Voltage Hot Swap Controller With
Wide Operating Range: 8.5V to 80V
2
ADC and I C Monitoring
LTC4261
Negative Voltage Hot Swap Controller With ADC
Floating Topology Allows Very High Voltage Operation
2
and I C Monitoring
2940f
LT 1109 • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
24
●
●
© LINEAR TECHNOLOGY CORPORATION 2009
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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