LT6105 [Linear]
Precision, Extended Input Range Current Sense Amplifi er; 精密，扩展输入范围电流检测器功率放大器
| 型号： | LT6105 |
| 厂家： | 
Linear |
| 描述： | Precision, Extended Input Range Current Sense Amplifi er |
| 文件： | 总20页 (文件大小：375K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT6105
Precision, Extended Input
Range Current Sense Amplifier
FEATURES
DESCRIPTION
Very Wide,Over-the-Top®, Input Common Mode Range
The LT®6105 is a micropower, precision current sense
amplifier with a very wide input common mode range.
The LT6105 monitors unidirectional current via the volt-
age across an external sense resistor. The input common
mode range extends from –0.3V to 44V, with respect to
n
–
+
- Extends 44V Above V (Independent of V )
–
- Extends –0.3V Below V
n
n
n
n
n
n
n
n
n
n
Wide Power Supply Range: 2.85V to 36V
Input Offset Voltage: 300μV Maximum
Gain Accuracy: 1% Max
–
the negative supply voltage (V ). This allows the LT6105
Gain Configurable with External Resistors
Operating Current: 150μA
Slew Rate: 2V/μs
Sense Input Current When Powered Down: 1nA
Full-Scale Output Current: 1mA Minimum
Operating Temperature Range –40°C to 125°C
Available in 2mm × 3mm DFN and 8-Lead MSOP
Packages
to operate as a high side current sense monitor or a low
side current sense monitor. It also allows the LT6105 to
monitor current on a negative supply voltage, as well as
continuouslymonitorabatteryfromfullchargetodepletion.
The inputs of LT6105 can withstand differential voltages
up to 44V, which makes it ideal for monitoring a fuse or
MOSFET switch.
Gain is configured with external resistors from 1V/V to
100V/V. The input common mode rejection and power
supplyrejectionareinexcessof100dBandtheinputoffset
voltage is less than 300μV. A typical slew rate of 2V/μs
ensures fast response to unexpected current changes.
APPLICATIONS
n
High Side or Low Side Current Sensing
n
Current Monitoring on Positive or Negative Supply
The LT6105 can operate from an independent power
supply of 2.85V to 36V and draws only 150μA. When
Voltages
Battery Monitoring
Fuse/MOSFET Monitoring
Automotive
Power Management
Portable Test/Measurement Systems
n
+
V is powered down, the sense pins are biased off. This
n
prevents loading of the monitored circuit, irrespective of
the sense voltage. The LT6105 is available in a 6-lead DFN
and 8-lead MSOP package.
n
n
n
, LT, LTC, LTM and Over-the-Top are registered trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Gain Error vs Input Voltage
4
+
V
V
R
A
= 12V
= 50mV
= 100Ω
= 50V
Gain of 50 Current Sense Amplifier
SENSE
3
2
IN
V
SOURCE
LT6105
–0.3V TO 44V
R
IN2
T
= –40°C
A
+
V
1
100Ω
S
+IN
–IN
+
–
T
= 25°C
A
V
0
OUT
R
100Ω
0.02Ω
V
= 1V/A
IN1
OUT
–1
–2
–3
–4
R
OUT
4.99k
T
= 125°C
T = 85°C
A
A
–
V
S
+
–
V
V
TO LOAD
2.85V TO 36V
6105 TA01
ROUT
RIN
ROUT
+
−
0
5
10 15 20 25 30 35 40 45
+
VOUT = V − VS
•
;
AV
=
; RIN1 = RIN2 = RIN
(
)
S
RIN
V
INPUT VOLTAGE (V)
6105 TA01b
S
6105fa
1
LT6105
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Specified Temperature Range (Note 5)
Differential Input Voltage (+IN – –IN)..................... 44V
–
LT6105C................................................... 0°C to 70°C
LT6105I................................................–40°C to 85°C
LT6105H ............................................–40°C to 125°C
Maximum Junction Temperature........................... 150°C
Storage Temperature Range...................–65°C to 150°C
Lead Temperature (Soldering, 10 sec)
Input Voltage V(+IN, –IN) to V ................–9.5V to 44V
+
–
Total V Supply Voltage from V ...............................36V
–
–
Output Voltage ......................................V to (V + 36V)
Output Short-Circuit Duration (Note 3) ............ Indefinite
Operating Temperature Range (Note 4)
LT6105C...............................................–40°C to 85°C
LT6105I................................................–40°C to 85°C
LT6105H ............................................–40°C to 125°C
MSOP ............................................................... 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
6
5
4
+IN
NC
V
–IN
1
2
3
–IN
V
1
2
3
8 +IN
7 NC
6 NC
5 V
+
+
7
V
NC
–
–
V
OUT
V
4
OUT
MS8 PACKAGE
8-LEAD PLASTIC MSOP
= 150°C, θ = 250°C/W
DCB PACKAGE
6-LEAD (2mm s 3mm) PLASTIC DFN
T
JMAX
JA
T
= 150°C, θ = 64°C/W
JMAX
JA
–
EXPOSED PAD (PIN 7) CONNECTED TO V (PIN 3)
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
SPECIFIED TEMPERATURE RANGE
LT6105CDCB#TRMPBF
LT6105IDCB#TRMPBF
LT6105HDCB#TRMPBF
LT6105CDCB#TRPBF
LT6105IDCB#TRPBF
LT6105HDCB#TRPBF
LCTF
LCTF
LCTF
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
6-Lead (2mm × 3mm) Plastic DFN
6-Lead (2mm × 3mm) Plastic DFN
6-Lead (2mm × 3mm) Plastic DFN
LT6105CMS8#PBF
LT6105IMS8#PBF
LT6105HMS8#PBF
LT6105CMS8#TRPBF
LT6105IMS8#TRPBF
LT6105HMS8#TRPBF
LTCTD
LTCTD
LTCTD
8-Lead Plastic MS8
8-Lead Plastic MS8
8-Lead Plastic MS8
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
6105fa
2
LT6105
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the temperature range
0°C < TA < 70°C (LT6105C), otherwise specifications are at TA = 25°C. V+ = 12V, V– = 0V, VS+ = 12V (see Figure 1), RIN1 = RIN2 = 100Ω,
–
ROUT = 5k (AV = 50), VSENSE = VS+ – VS , unless otherwise specified. (Note 5)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
+
–
V , V
Input Voltage Range
Guaranteed by CMRR
–0.3
–0.1
44
44
V
V
S
S
l
+
A Error
Voltage Gain Error (Note 6)
V
= 25mV to 75mV, V = 12V
–1
0.1
1
%
%
V
SENSE
S
l
l
–1.3
1.3
+
V
V
= 25mV to 75mV, V = 0V
–2.5
2.5
%
SENSE
S
V
Input Offset Voltage
MS8 Package
= 5mV
–0.3
–0.6
–0.1
–0.1
–0.3
0.3
0.6
mV
mV
OS
SENSE
l
l
Input Offset Voltage
DCB Package
V
V
= 5mV
–0.4
–0.7
0.4
0.7
mV
mV
SENSE
SENSE
+
Input Offset Voltage
= 5mV, V = 0V
–1
–1.3
1
1.3
mV
mV
S
l
l
Temperature Coefficient of V
0.5
μV/°C
ΔV /ΔT
OS
OS
+
CMRR
Input Common Mode
Rejection Ratio
V
= 5mV, V = 2.8V to 44V
100
95
120
dB
dB
SENSE
S
l
+
+
V
V
= 5mV, V = –0.3V to 44V
94
90
dB
dB
SENSE
SENSE
S
l
l
= 5mV, V = –0.1V to 44V
S
+
V
Power Supply Voltage Range
Power Supply Rejection Ratio
Guaranteed by PSRR
2.85
36
V
+
+
PSRR
V
= 5mV, V = 12V, V = 2.85V to 36V
98
94
120
120
dB
dB
SENSE
S
l
l
+
+
V
SENSE
= 5mV, V = 0V, V = 2.85V to 36V
98
94
dB
dB
S
+
+
l
l
I
I
, I
Input Current
V
V
= 0V, V = 3V
15
25
0.5
1
μA
μA
(+IN) (–IN)
SENSE
SENSE
S
= 0V, V = 0V
–0.05
S
+
l
l
– I
Input Offset Current
Input Current (Power-Down)
V
V
= 0V, V = 3V
0.05
0.005
μA
μA
(+IN)
(–IN)
SENSE
SENSE
+
S
S
+
= 0V, V = 0V
+
l
I
I
I
V = 0V, V = 44V, V
= 0V
0.03
μA
(+IN) + (–IN)
S
SENSE
+
+
+
+
l
l
V Supply Current
V
V
= 0V, V = 3V, V = 2.85V
200
240
300
350
μA
μA
S
SENSE
SENSE
S
+
= 0V, V = 3V, V = 36V
S
+
+
l
l
l
l
V
V
Minimum Output Voltage
V
= 0mV, V = 44V, V = 36V
35
mV
V
O(MIN)
O(MAX)
OUT
SENSE
SENSE
S
+
Output High (Referred to V )
V
= 120mV, A = 100, R
= 10k
1.25
1.5
V
OUT
I
I
Maximum Output Current
Short-Circuit Output Current
–3dB Bandwidth
Guaranteed by V
1
mA
mA
kHz
μs
O(MAX)
+
–
V
V
V
V
V
= 44V, V = 0V, R = 0Ω
OUT
1.5
SC
S
S
BW
= 50mV, A = 10V/V
100
5
SENSE
SENSE
SENSE
SENSE
V
t
S
t
r
Output Settling to 1% of Final Value
Input Step Response (Note 7)
Slew Rate (Note 8)
= 5mV to 100mV
= 5mV to 100mV
3
μs
SR
= 5mV to 150mV, A = 50V/V, R = 400Ω
1.75
–9.5
2
V/μs
V
V
IN
l
V
Reverse Input Voltage
I
I = –5mA
(+IN) + (–IN)
–12
REV
–
(Referred to V )
6105fa
3
LT6105
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the temperature range
–40°C < TA < 85°C (LT6105I), otherwise specifications are at TA = 25°C. V+ = 12V, V– = 0V, VS+ = 12V (see Figure 1), RIN1 = RIN2
=
–
100Ω, ROUT = 5k (AV = 50), VSENSE = VS+ – VS , unless otherwise specified. (Note 5)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
+
–
V , V
Input Voltage Range
Guaranteed by CMRR
–0.3
–0.3
44
44
V
V
S
S
l
+
A Error
Voltage Gain Error (Note 6)
V
= 25mV to 75mV, V = 12V
–1
0.1
1
%
%
V
SENSE
S
l
l
–1.4
1.4
+
V
V
= 25mV to 75mV, V = 0V
–3
3
%
SENSE
S
V
Input Offset Voltage
MS8 Package
= 5mV
–0.3
–0.65
–0.1
–0.1
–0.3
0.3
0.65
mV
mV
OS
SENSE
l
l
Input Offset Voltage
DCB Package
V
V
= 5mV
–0.4
–0.75
0.4
0.75
mV
mV
SENSE
+
Input Offset Voltage
= 5mV, V = 0V
–1
–1.4
1
1.4
mV
mV
SENSE
S
l
l
Temperature Coefficient of V
0.5
μV/°C
ΔV /ΔT
OS
OS
+
CMRR
Input Common Mode
Rejection Ratio
V
SENSE
= 5mV, V = 2.8V to 44V
100
95
120
dB
dB
S
l
+
+
V
V
= 5mV, V = –0.3V to 44V
94
90
dB
dB
SENSE
SENSE
S
l
l
= 5mV, V = –0.1V to 44V
S
+
V
Power Supply Voltage Range
Power Supply Rejection Ratio
Guaranteed by PSRR
2.85
36
V
+
+
PSRR
V
= 5mV, V = 12V, V = 2.85V to 36V
98
94
120
120
dB
dB
SENSE
S
l
l
+
+
V
= 5mV, V = 0V, V = 2.85V to 36V
98
94
dB
dB
SENSE
S
+
+
l
l
I
I
, I
Input Current
V
V
= 0V, V = 3V
16
27
0.6
1
μA
μA
(+IN) (–IN)
SENSE
SENSE
S
= 0V, V = 0V
–0.05
S
+
l
l
– I
Input Offset Current
Input Current (Power-Down)
V
SENSE
V
SENSE
+
= 0V, V = 3V
0.08
0.01
μA
μA
(+IN)
(–IN)
S
S
+
= 0V, V = 0V
+
l
I
I
I
V = 0V, V = 44V, V
= 0V
0.035
μA
(+IN) + (–IN)
S
SENSE
+
+
+
+
l
l
V Supply Current
V
V
= 0V, V = 3V, V = 2.85V
200
250
325
375
μA
μA
S
SENSE
SENSE
S
+
= 0V, V = 3V, V = 36V
S
+
+
l
l
l
l
V
V
Minimum Output Voltage
V
V
= 0mV, V = 44V, V = 36V
40
mV
V
O(MIN)
O(MAX)
OUT
SENSE
SENSE
S
+
Output High (Referred to V )
= 120mV, A = 100, R
= 10k
1.27
1.6
V
OUT
I
I
Maximum Output Current
Short-Circuit Output Current
–3dB Bandwidth
Guaranteed by V
1
mA
mA
kHz
μs
O(MAX)
+
–
V
V
V
V
V
= 44V, V = 0V, R = 0Ω
OUT
1.5
SC
S
S
BW
= 50mV, A = 10V/V
100
5
SENSE
SENSE
SENSE
SENSE
V
t
t
Output Settling to 1% of Final Value
Input Step Response (Note 7)
Slew Rate (Note 8)
= 5mV to 100mV
= 5mV to 100mV
S
r
3
μs
SR
= 5mV to 150mV, A = 50V/V, R = 400Ω
1.75
–9.5
2
V/μs
V
V
IN
l
V
Reverse Input Voltage
I
I = –5mA
(+IN) + (–IN)
–12
REV
–
(Referred to V )
6105fa
4
LT6105
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the temperature range
–40°C < TA < 125°C (LT6105H), otherwise specifications are at TA = 25°C. V+ = 12V, V– = 0V, VS+ = 12V (see Figure 1), RIN1 = RIN2
=
–
100Ω, ROUT = 5k (AV = 50), VSENSE = VS+ – VS , unless otherwise specified. (Note 5)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
+
–
V , V
Input Voltage Range
Guaranteed by CMRR
–0.3
–0.1
44
44
V
V
S
S
l
+
A Error
Voltage Gain Error (Note 6)
V
= 25mV to 75mV, V = 12V
–1
0.1
1
%
%
V
SENSE
S
l
l
–1.5
1.5
+
V
V
= 25mV to 75mV, V = 0V
–3.25
3.25
%
SENSE
S
V
Input Offset Voltage
MS8 Package
= 5mV
–0.3
–0.8
–0.1
–0.1
–0.3
0.3
0.8
mV
mV
OS
SENSE
l
l
Input Offset Voltage
DCB Package
V
V
= 5mV
–0.4
–0.9
0.4
0.9
mV
mV
SENSE
+
Input Offset Voltage
= 5mV, V = 0V
–1
–1.6
1
1.6
mV
mV
SENSE
S
l
l
Temperature Coefficient of V
0.5
μV/°C
ΔV /ΔT
OS
OS
+
CMRR
Input Common Mode
Rejection Ratio
V
SENSE
= 5mV, V = 2.8V to 44V
100
95
120
dB
dB
S
l
+
+
V
V
= 5mV, V = –0.3V to 44V
94
80
dB
dB
SENSE
SENSE
S
l
l
= 5mV, V = –0.1V to 44V
S
+
V
Power Supply Voltage Range
Power Supply Rejection Ratio
Guaranteed by PSRR
2.85
36
V
+
+
PSRR
V
= 5mV, V = 12V, V = 2.85V to 36V
98
94
120
120
dB
dB
SENSE
S
l
l
+
+
V
= 5mV, V = 0V, V = 2.85V to 36V
98
94
dB
dB
SENSE
S
+
+
l
l
I
I
, I
Input Current
V
V
= 0V, V = 3V
18
30
0.8
2.5
μA
μA
(+IN) (–IN)
SENSE
SENSE
S
= 0V, V = 0V
–0.05
S
+
l
l
– I
Input Offset Current
Input Current (Power-Down)
V
SENSE
V
SENSE
+
= 0V, V = 3V
0.35
0.1
μA
μA
(+IN)
(–IN)
S
S
+
= 0V, V = 0V
+
l
I
I
I
V = 0V, V = 44V, V
= 0V
0.5
μA
(+IN) + (–IN)
S
SENSE
+
+
+
+
l
l
V Supply Current
V
V
= 0V, V = 3V, V = 2.85V
240
300
350
450
μA
μA
S
SENSE
SENSE
S
+
= 0V, V = 3V, V = 36V
S
+
+
l
l
l
l
V
V
Minimum Output Voltage
V
V
= 0mV, V = 44V, V = 36V
45
mV
V
O(MIN)
O(MAX)
OUT
SENSE
SENSE
S
+
Output High (Referred to V )
= 120mV, A = 100, R
= 10k
1.3
1.7
V
OUT
I
I
Maximum Output Current
Short-Circuit Output Current
–3dB Bandwidth
Guaranteed by V
1
mA
mA
kHz
μs
O(MAX)
+
–
V
V
V
V
V
= 44V, V = 0V, R = 0Ω
OUT
1.5
SC
S
S
BW
= 50mV, A = 10V/V
100
5
SENSE
SENSE
SENSE
SENSE
V
t
t
Output Settling to 1% of Final Value
Input Step Response (Note 7)
Slew Rate (Note 8)
= 5mV to 100mV
= 5mV to 100mV
S
r
3
μs
SR
= 5mV to 150mV, A = 50V/V, R = 400Ω
1.75
–9.5
2
V/μs
V
V
IN
l
V
Reverse Input Voltage
I
I = –5mA
(+IN) + (–IN)
–12
REV
–
(Referred to V )
6105fa
5
LT6105
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.
guaranteed functional over the operating temperature range of –40°C
to 125°C.
Note 5: The LT6105C is guaranteed to meet specified performance from
0°C to 70°C. The LT6105C is designed, characterized and expected to
meet specified performance from –40°C to 85°C but is not tested or
QA sampled at these temperatures. The LT6105I is guaranteed to meet
specified performance from –40°C to 85°C. The LT6105H is guaranteed to
meet specified performance from –40°C to 125°C.
Note 2: ESD (Electrostatic Discharge) sensitive devices. Extensive use
of ESD protection devices are used internal to the LT6105, however, high
electrostatic discharge can damage or degrade the device. Use proper ESD
handling precautions.
Note 3: A heat sink may be required to keep the junction temperature
Note 6: 0.01% tolerance external resistors are used.
below absolute maximum ratings.
Note 7: t is measured from the input to the 2.5V point on the 5V output.
r
Note 4: The LT6105C/LT6105I are guaranteed functional over the
operating temperature range of –40°C to 85°C. The LT6105H is
Note 8: Slew rate is measured on the output between 1V and 5V.
TYPICAL PERFORMANCE CHARACTERISTICS
Input Offset Voltage
Input Offset Voltage
Input Offset Voltage
vs Input Voltage
vs Temperature, VS+ = 12V
vs Temperature, VS+ = 0V
400
300
0.80
0.60
1000
800
+
+
+
V
V
= 12V
= 5mV
V
V
A
= 12V
= 5mV
V
V
= 12V
= 5mV
SENSE
SENSE
V
SENSE
TYPICAL UNITS
= 50V/V
TYPICAL UNITS
600
0.40
200
T
= 25°C
A
400
0.20
100
T
T
= –40°C
= 125°C
200
A
A
0
0
0
–0.20
–0.40
–0.60
–0.80
–1.00
–200
–400
–600
–800
–1000
–100
–200
–300
–400
T
= 85°C
A
–10
5
20 35 50
125
–40 –25
65 80 95 110
10 15 20 25 30
+
45
0
5
35 40
–10
5
20 35 50
125
–40 –25
65 80 95 110
TEMPERATURE (°C)
V
INPUT VOLTAGE (V)
TEMPERATURE (°C)
S
6105 G01
6105 G03
6105 G02
Input Offset Voltage
Input Offset Voltage
Gain Error Distribution,
vs Supply Voltage, VS+ = 12V
vs Supply Voltage, VS+ = 0V
VS+ = 12V
0.2
0.0
40
35
30
25
20
15
10
5
0.8
0.6
+
V
= 5mV
V
V
= 12V
= 50mV
V
= 5mV
SENSE
SENSE
SENSE
R
= 100Ω
IN
A
= 50V/V
V
–0.2
–0.4
–0.6
–0.8
–1.0
–1.2
–1.4
0.4
500 SAMPLES
T
= 25°C
= 85°C
A
0.2
T
= 25°C
A
T
A
0.0
T
= –40°C
A
T
T
= –40°C
T = 125°C
A
A
–0.2
–0.4
–0.6
–0.8
= 85°C
A
T
= 125°C
A
0
10 15 20 25 30
+
0
5
35 40
–0.3–0.2–0.1
0
0.1
0.5
0.2 0.3 0.4
–0.5–0.4
10 15 20 25 30
+
40
0
5
35
V
SUPPLY VOLTAGE (V)
GAIN ERROR (%)
V
SUPPLY VOLTAGE (V)
6105 G04
6105 G05
6105 G06
6105fa
6
LT6105
TYPICAL PERFORMANCE CHARACTERISTICS
Gain Error Distribution,
Gain Error vs Temperature,
VS+ = 0V
Gain Error vs Input Voltage
VS+ = 12V
4
3
45
40
35
30
25
20
15
10
5
0.5
0.4
+
+
+
V
V
R
A
= 12V
= 50mV
V
V
= 12V
= 50mV
V
V
= 12V
= 50mV
SENSE
SENSE
SENSE
= 100Ω
IN
= 50V
V
R
A
= 100Ω
R
A
= 100Ω
IN
IN
V
0.3
= 50V/V
= 50V/V
V
2
500 SAMPLES
0.2
T
= –40°C
A
1
0.1
T
= 25°C
A
0
0.0
–0.1
–0.2
–0.3
–0.4
–0.5
–1
–2
–3
–4
T
= 125°C
T = 85°C
A
A
0
10 15 20 25 30
+
45
0
5
35 40
–2.1 –2.0 –1.9 –1.8 –1.7
–1.4
–1.6 –1.5
–2.3 –2.2
–50 –25
0
25
50
75 100 125
V
INPUT VOLTAGE (V)
TEMPERATURE (°C)
GAIN ERROR (%)
S
6105 G08
6105 G07
6105 G09
Input Referred Voltage Error
vs VSENSE, VS+ = 12V
Gain Error vs Temperature,
VS+ = 0V
Gain Error vs Output Resistance
6
5
2
1
0
–0.4
–0.8
–1.2
–1.6
–2.0
–2.4
–2.8
–3.2
–3.6
–4.0
+
+
V
V
R
A
= 12V
V
R
A
= 12V
V
V
= 12V
= 50mV
IN
SENSE
= 50mV
= 100Ω
IN
V
SENSE
4
= 100Ω
IN
= R /R
OUT IN
= 50V/V
R
A
= 100Ω
IN
V
= 50V/V
V
3
T
= 85°C
A
2
1
+
+
T
T
= 125°C
A
V
V
= 12V
= 0V
S
S
0
0
–1
–2
–3
–4
–5
–6
= –40°C
A
T
= 25°C
A
–1
–2
0
2000
4000
6000
8000 10000
0
20
40
V
60
(mV)
80
100
120
–50 –25
0
25
50
75 100 125
R
OUTPUT RESISTANCE (Ω)
TEMPERATURE (°C)
OUT
SENSE
6105 G11
6105 G12
6105 G10
Input Bias Current
vs Input Voltage
Input Current vs Input Voltage,
VSENSE = 50mV
Input Referred Voltage Error
vs VSENSE, VS+ = 0V
2.0
1.5
5.0
4.0
100.00
10.00
1.00
+
+
+
V
R
A
= 12V
V
R
A
= 12V
V
V
= 3V
= 100Ω
= 50V/V
= 100Ω
= 0V
IN
V
IN
V
SENSE
= 50V/V
R
= 100Ω
IN
3.0
1.0
2.0
0.1
I
(+IN)
T
= –40°C
T
= 125°C
T = –40°C
A
A
T
A
0.5
1.0
0.01
= 25°C
A
I
(–IN)
T
= 85°C
A
0.0
0.0
0
T
= 25°C
A
–1.0
–2.0
–3.0
–4.0
–5.0
–0.01
–0.10
–1.00
–10.00
–100.00
–0.5
–1.0
–1.5
–2.0
T
= 125°C
A
T
= 85°C
A
10 15 20 25 30
+
45
0
5
35 40
0
20
40
V
60
(mV)
80
100
120
0
0.5
V
1.5
2
2.5
3
1
+
INPUT VOLTAGE (V)
V
INPUT VOLTAGE (V)
SENSE
S
S
6105 G15
6105 G13
6105 G14
6105fa
7
LT6105
TYPICAL PERFORMANCE CHARACTERISTICS
Input Current (V+ Powered
Down) vs Input Voltage
Output Voltage vs VSENSE Voltage,
VS+ = 12V
Output Voltage vs VSENSE Voltage,
VS+ = 0V
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1000
100
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
+
+
V
R
A
= 3V
V
R
A
= 3V
T
= 125°C
A
= 100Ω
= 10V/V
= 100Ω
= 10V/V
IN
V
IN
V
T
= 85°C
10
A
T
A
(–40°C, 25°C, 85°C, 125°C)
1
T
= –40°C
A
T
(25°C, 85°C, 125°C)
A
0.1
T
T
= 25°C
A
0.01
0.001
0.0001
= –40°C
A
+
V
V
= 0V
= 0V
SENSE
70
90 110 130
70
90 110 130
–10 10
30
50
–10 10
30
50
0
5
10 15 20 25 30 35 40 45 50
+
V
(mV)
V
(mV)
V
INPUT VOLTAGE (V)
SENSE
SENSE
S
6105 G18
6105 G17
6105 G16
Output Saturation Voltage
Output Saturation Voltage
Output Short-Circuit
vs Output Current, VS+ = 12V
vs Output Current, VS+ = 0.5V
Current vs Temperature
3.4
3.2
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
+
+
+
V
V
V
= 5V
V
V
R
= 12V
= 0.5V
V
V
R
= 12V
= 0.5V
+
= 5V
S
SENSE
IN
SENSE
IN
= 5V
= 100Ω
= 100Ω
SENSE
IN
R
= 100Ω
3.0
T
T
= –40°C
= 25°C
T
= 85°C
A
A
T
= 125°C
= –40°C
2.8
2.6
2.4
2.2
A
A
T
= 85°C
A
T
A
T
= 25°C
A
T
= 125°C
A
+
+
OUTPUT SATURATION VOLTAGE = V – V
OUTPUT SATURATION VOLTAGE = V – V
OUT
OUT
2.0
–10
5
20 35 50
125
0.001
0.01
0.10
1
10
–40 –25
65 80 95 110
0.001
0.01
0.10
1
10
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
TEMPERATURE (°C)
6105 G21
6105 G19
6105 G20
Supply Current vs Supply Voltage,
VS+ = 12V
Supply Current vs Supply Voltage,
VS+ = 0V
Supply Current vs Input Voltage
500
400
300
200
100
0
500
400
300
200
100
0
400
350
300
250
200
150
100
50
+
V
R
A
= 0V
SENSE
V
V
= 3V
V
R
A
= 0V
SENSE
IN
V
= 100Ω
IN
= 0V
= 100Ω
SENSE
= 50V/V
V
R
= 100Ω
= 50V/V
IN
T
= 125°C
= 85°C
A
T
= 125°C
= 85°C
T
= 125°C
= 85°C
= 25°C
A
A
T
A
T
A
T
A
T
T
= 25°C
A
T
= 25°C
A
A
T
A
A
= –40°C
A
T
= –40°C
T
= –40°C
0
10 15 20 25 30 35 40
+
0
5
10 15 20 25 30
+
35 40
45
10 15 20 25 30
+
0
5
0
5
35 40
V SUPPLY VOLTAGE (V)
V
INPUT VOLTAGE (V)
V
SUPPLY VOLTAGE (V)
S
6105 G24
6105 G22
6105 G23
6105fa
8
LT6105
TYPICAL PERFORMANCE CHARACTERISTICS
Common Mode Rejection
Ratio vs Frequency
Power Supply Rejection
Ratio vs Frequency
Gain vs Frequency
140
120
100
80
160
140
120
100
80
40
30
+
+
+
+
V
V
= 12V
= 5mV
V
V
= 12V
V
V
= V = 12V
S
+
= 12V
= 50mV
= 100Ω
= 10V/V
SENSE
S
SENSE
+
R
A
= 100Ω
R
A
= 100Ω
= 50V/V
V
= 12V
R
A
IN
V
IN
V
S
IN
V
= 10V/V
20
10
+
V
= 0V
S
0
60
60
–10
–20
–30
–40
40
40
20
20
0
0.1
0
100
1k
10k
100k
1M
10M
1k
10k
100k
FREQUENCY (Hz)
1M
10M
1
10 100
1k
10k 100k 1M
FREQUENCY (Hz)
FREQUENCY (Hz)
6105 G27
6105 G26
6105 G25
Step Response
VSENSE = 0V to 100mV, VS+ = 12V
Step Response
VSENSE = 0V to 100mV, VS+ = 0V
Slew Rate vs RIN
2.5
2.0
1.5
0V
–
12V
–
V
S
V
S
+SLEW RATE
100mV/DIV
100mV/DIV
–SLEW RATE
V
V
OUT
OUT
1.0
0.5
0
500mV/DIV
500mV/DIV
0V
0V
+
V
V
V
A
= 12V
+
= 12V
6105 G30
S
6105 G29
50μs/DIV
= 10k
50μs/DIV
= 10k
= 7.5V
= 50V/V
OUT
V
+
+
V
R
= 12V
= 1k
R
A
V
R
= 12V
= 1k
R
A
OUT
OUT
= 10V/V
V
= 10V/V
V
IN
IN
0
100 200 300 400 500 600 700 800 9001000
(Ω)
R
IN
6105 G28
Step Response
Step Response
VSENSE = 0V to 100mV, RIN = 100Ω
Step Response
VSENSE = 5mV to 100mV
V
SENSE = 0V to 100mV
11.995V
–
12V
–
12V
–
V
S
V
S
V
S
100mV/DIV
100mV/DIV
100mV/DIV
5V
V
5V
OUT
V
OUT
V
2V/DIV
0V
OUT
2V/DIV
0V
2V/DIV
0V
6105 G33
6105 G31
6105 G32
5μs/DIV
= 50k
50μs/DIV
5μs/DIV
+
+
+
V
V
= 12V
= 12V
= 1k
R
A
V
V
A
= 12V
V
V
= 12V
= 12V
= 1k
R
A
= 50k
OUT
= 50V/V
V
OUT
+
+
+
= 50V/V
V
= 12V
S
S
V
S
R
IN
= 50V/V
R
IN
6105fa
9
LT6105
TYPICAL PERFORMANCE CHARACTERISTICS
Step Response
Step Response
VSENSE = 100mV to 5mV
Step Response
VSENSE = 0V to 10mV, VS+ = 12V
VSENSE = 0V to 10mV, VS+ = 0V
11.995V
12V
–
0V
S
10mV/DIV
–
V
–
S
V
S
V
100mV/DIV
10mV/DIV
V
5V
OUT
2V/DIV
V
V
OUT
OUT
200mV/DIV
0V
200mV/DIV
0V
0V
6105 G35
6105 G34
6105 G36
50μs/DIV
= 5k
5μs/DIV
= 50k
50μs/DIV
+
+
+
V
= 12V
R
A
V
V
= 12V
= 12V
= 1k
R
A
V
R
= 12V
R
= 5k
OUT
OUT
OUT
+
R
= 100Ω
= 50V/V
V
= 50V/V
V
= 100Ω
A
= 50V/V
V
IN
S
IN
R
IN
Step Response
Step Response
Step Response
VSENSE = 0V to 100mV,
VSENSE = 0V to 10mV,
VSENSE = 0V to 100mV,
CL = 1000pF, VS+ = 12V
CL = 1000pF, VS+ = 12V
CL = 1000pF, VS+ = 0V
12V
–
12V
–
0V
–
V
V
V
S
S
S
100mV/DIV
10mV/DIV
100mV/DIV
V
V
V
OUT
2V/DIV
0V
OUT
OUT
2V/DIV
200mV/DIV
0V
0V
6105 G37
6105 G38
6105 G39
50μs/DIV
+
50μs/DIV
+
50μs/DIV
+
V
R
R
= 12V
A
V
C
L
= 50V/V
V
R
R
= 12V
A
V
C
L
= 50V/V
V
R
R
= 12V
A
V
C
L
= 50V/V
= 100Ω
= 5k
= 1000pF
= 100Ω
= 5k
= 1000pF
= 100Ω
= 5k
= 1000pF
IN
IN
IN
OUT
OUT
OUT
Step Response
VSENSE = 0V to 10mV,
CL = 1000pF, VS+ = 0V
Power Supply Start-Up Response
5V
0V
S
10mV/DIV
+
–
V
V
0V
V
OUT
1V/DIV
0V
V
OUT
200V/DIV
0V
6105 G40
6105 G41
50μs/DIV
+
20μs/DIV
+
V
R
R
= 12V
A
V
C
L
= 50V/V
V
V
= 12V
R
= 1k
IN
S
= 100Ω
= 5k
= 1000pF
= 100mV
A
= 10V/V
V
IN
SENSE
OUT
6105fa
10
LT6105
PIN FUNCTIONS (DCB/MS8)
–IN (Pin 1/Pin 1): Negative Sense Input Terminal.
V
is the input offset voltage. A is the gain set by exter-
OS V
nal R , R , R . A = R /R , for R = R
Negative sense voltage input will remain functional for
.
IN1 IN2 OUT
V
OUT IN1
IN1
IN2
–
voltages up to 44V, referred to V . Connect –IN to an
NC (Pin 5/Pins 3, 6, 7): Not Connected Internally.
+IN (Pin 6/Pin 8): Positive Sense Input Terminal.
external gain-setting resistor R (R = R ) to set
IN1
IN1
IN2
the gain.
+
–
Connecting a source to V and a load to V will allow the
S
S
+
V (Pin 2/Pin 2): Power Supply Voltage. This pin supplies
currenttotheamplifierandcanoperatefrom2.85Vto36V,
independent of the voltages on the –IN or +IN pins.
LT6105 to monitor the current through R
, refer to
SENSE
Figure 1. Connect +IN to an external gain-setting resistor
R
to set the gain. +IN remains functional for voltages
IN2
–
–
V (Pin3/Pin4):NegativePowerSupplyVoltageorGround
up to 44V, referred to V .
for Single Supply Operation.
–
Exposed Pad (Pin 7) DFN Only: V . The Exposed Pad is
–
V
(Pin 4/Pin 5): Voltage Output:
connected to the V pin. It should be connected to the
OUT
–
V trace of the PCB, or left floating.
V
= A • (V
V )
OS
OUT
V
SENSE
BLOCK DIAGRAM
V
SENSE
R
SENSE
V –
S
V +
S
SOURCE
0V TO 44V
TO LOAD
R
R
IN2
IN1
–IN
+IN
SET R = R FOR BEST ACCURACY
IN1
IN2
LT6105
R
R
OUT
V
V
> 1.6V: V
< 1.6V: V
= V
= V
•
•
(–IN)
(–IN)
OUT
OUT
SENSE
SENSE
+
IN2
V
IF R ≠ R , THEN
IN1
IN2
+
–
+
–
R
OUT
R
IN1
A1
A2
Q2
Q3
R , R , R
IN1 IN2 OUT
ARE EXTERNAL RESISTORS
Q1
V
OUT
R
R
OUT
–
V
= V
•
SENSE
V
OUT
IN
WHERE R = R = R
IN
IN1
IN2
R
OUT
R
OUT
A
=
V
R
IN
6105 F01
Figure 1. Simplified Block Diagram
6105fa
11
LT6105
APPLICATIONS INFORMATION
The LT6105 extended input range current sense am-
plifier (see Figure 1) provides accurate unidirectional
monitoringofcurrentthroughauser-selectedsenseresis-
tor. The LT6105 is fully specified over a –0.3V to 44V input
Selection of External Current Sense Resistor
External R resistor selection is a delicate trade-off
between power dissipation in the resistor and current
measurement accuracy. For high current applications, the
user may want to minimize the sense voltage to minimize
the power dissipation in the sense resistor.
SENSE
+
common mode range. A high PSRR V supply (2.85V to
36V) powers the current sense amplifier. The input sense
voltage is level shifted from the sensed power supply to
thegroundreferenceandamplifiedbyauser-selectedgain
to the output. The output voltage is directly proportional
to the current flowing through the sense resistor.
The system load current will cause both heat and voltage
loss in R
. As a result, the sense resistor should be as
SENSE
small as possible while still providing the input dynamic
range required by the measurement. Note that input dy-
namic range is the difference between the maximum input
signal and the minimum accurately reproduced signal,
and is limited primarily by input DC offset voltage of the
internal amplifier of the LT6105.
THEORY OF OPERATION
(Refer to Figure 1)
Case 1: High Input Voltage (1.6V < V < 44V)
–IN
+
The sense resistor value will be set from the minimum
signalcurrentthatcanbeaccuratelyresolvedbythissense
amp. As an example, the LT6105 has a typical input offset
of100μV.Iftheminimumcurrentis20mA,asenseresistor
Current from the source at V flows through R
to
SENSE
S
–
the load at V , creating a sense voltage, V
. Inputs
S
SENSE
+
–
V
and V apply the sense voltage to R . The opposite
S
S IN2
ends of resistors R and R are forced to be at equal
IN1
IN2
of 5mΩ will set V
to 100μV, which is the same value
SENSE
potentials by the voltage gain of amplifier A2. Thus, the
current through R is V /R . The current through
as the input offset. A larger sense resistor will reduce the
error due to offset by increasing the sense voltage for
a given load current, but it will limit the maximum peak
current for a given application.
IN2
SENSE IN2
R
R
is forced to flow through transistor Q1 and into
IN2
OUT
, creating an output voltage, V . Under this input
OUT
operation range, amplifier A1 is kept off. The base current
of Q1 has been compensated for and will not contribute
For a peak current of 2A and a maximum V
SENSE
of 80mV,
SENSE
to output error. The current from R flowing through
R
should not be more than 40mΩ. The input offset
IN2
resistor R
OUT IN2
gives an output voltage of V
/R , producing a gain voltage of A = V /V
= V
•
causes an error equivalent to only 2.5mA of load current.
Peak dissipation is 160mW. If a 20mΩ sense resistor is
employed, then the effective current error is 5mA, while
the peak sense voltage is reduced to 40mV at 2A, dis-
sipating only 80mW.
OUT
OUT
SENSE
R
V OUT SENSE
= R /R
.
OUT IN2
Case 2: Low Input Voltage (0V < V < 1.6V)
–IN
+
Current from the source at V flows through R
to
SENSE
. Inputs
S
The LT6105’s low input offset voltage of 100μV allows for
highresolutionwhilelimitingthemaximumsensevoltages.
Coupled with full scale sense voltage as large as 1V for
–
the load at V , creating a sense voltage, V
S
SENSE
+
–
V
and V apply the sense voltage to R . The opposite
S
S IN1
ends of resistors R and R are forced to be at equal
IN1
IN2
R = 1k, it can achieve 80dB of dynamic range.
IN
potentials by the voltage gain of amplifier A1. Thus, the
collector current of Q3 will flow out of the –IN pin through
Sense Resistor Connection
R
IN1
. Q2 mirrors this current V
/R to R , creat-
SENSE IN1 OUT
Kelvin connection of the LT6105’s input resistors to the
senseresistorshouldbeimplementedtoprovidethehigh-
est accuracy in high current applications. Solder connec-
tionsandPCboardinterconnectresistance(approximately
0.5mΩ per square for 1oz copper) can be a large error
in high current systems. A 5A application might choose
6105fa
ing an output voltage, V . Under this input operation
OUT
range, amplifier A2 is kept off. This current V
/R
SENSE IN1
flowing through resistor R
gives an output voltage of
OUT
V
= V
• R /R , producing a gain voltage of
OUT
SENSE OUT IN1
A = V /V
= R /R
.
V
OUT SENSE
OUT IN1
12
LT6105
APPLICATIONS INFORMATION
is 1mA. This allows low value output resistors to be used
which helps preserve signal accuracy when the output pin
is connected to other systems.
a 20mΩ sense resistor to give a 100mV full-scale input
to the LT6105. Input offset voltage will limit resolution to
5mA. Neglecting contact resistance at solder joints, even
one square of PC board copper at each resistor end will
cause an error of 5%. This error will grow proportionately
higher as monitored current levels rise.
For zero V
, the internal circuitry gain will force V
SENSE
OUT
–
to V
referred to V . Depending on output currents,
O(MIN)
+
V
may swing positive to within V
referred to V
OUT
O(MAX)
oramaximumof36V, alimitsetbyinternaljunctionbreak-
down. Within these constraints, an amplified, level shifted
representationofR
output is well behaved driving capacitive loads.
Gain Setting
The gain is set with three external resistors, R , R
,
voltageisdevelopedatV .The
OUT
IN1 IN2
SENSE
R
. The gain, R /R , can be selected from 1V/V to
OUT
OUT IN
100V/V as long as the maximum current does not exceed
CM Input Signal Range
1mA. Select Gain = R /R for sense input voltage op-
OUT IN2
erationgreaterthan1.6V.Selectgain=R /R forsense
OUT IN1
The LT6105 has high CMRR over the full input voltage
range.Theminimumoperationvoltageofthesenseampli-
input voltage operation less than 1.6V. The overall system
error will depend on the resistor tolerance chosen for the
+
fier inputs is 0V whether V is at 2.7V or 36V. The output
application. Set R = R
for best accuracy across the
IN1
IN2
remains accurate even when the sense inputs are driven
entire input range. The total error will be gain error of the
to 44V. The graph in Figure 2 shows that V changes very
OS
resistors plus the gain error of the LT6105 device.
slightlyoverawideinputrange. Furthermore, eithersense
+
–
inputsV andV cancollapseto0Vwithoutincurringany
S
S
Output Signal Range
damage to the device. The LT6105 can handle differential
+
–
The LT6105’s output signal is developed by current
sensevoltagesupto44V.Forexample,V =44VandV =
S S
through R (44V > V > 1.6V) or R (0V < V <
0Vcanbeavalidconditioninacurrentmonitoringapplica-
IN2
–IN
IN1
–IN
tion (Figure 3) when an overload protection fuse is blown
1.6V) conducted to the output resistor, R . This current
OUT
–
andV voltagecollapsestoground. Underthiscondition,
isV
/R orV
/R .Thesenseamplifier’smaxi-
mum output current before gain error begins to increase
S
SENSE IN2
SENSE IN1
the output of the LT6105 goes to the positive rail, V
.
O(MAX)
TO LOAD
R
FUSE
0.80
+
+
–
SENSE
V
V
S
S
DC SOURCE
(≤ 44V)
V
V
A
= 12V
= 5mV
0.60
0.40
SENSE
V
R
R
IN2
IN1
C1
= 50V/V
0.1MF
T
= 25°C
A
–IN
+
+IN
0.20
T
T
= –40°C
= 125°C
A
A
V
0
+
C2
0.1MF
–
+
5V
–0.20
–0.40
–0.60
–0.80
–1.00
T
= 85°C
A
–
V
10 15 20 25 30
+
45
0
5
35 40
OUT
OUTPUT
V
INPUT VOLTAGE (V)
LT6105
S
6105 F02
R
OUT
6105 F03
Figure 2. Input Offset Voltage vs VS+ Input Voltage
Figure 3. Current Monitoring of a Fuse Protected Circuit
6105fa
13
LT6105
APPLICATIONS INFORMATION
There is no phase inversion. For the opposite case, when
If the circuit to be driven has high input impedance, then
almost any useful output impedance will be acceptable.
However,ifthedrivencircuithasrelativelylowinputimped-
ance, or draws spikes of current such as an ADC might
+
–
V
collapses to ground with V held up at some higher
S
S
voltage potential, the output will sit at V
.
O(MIN)
The Two Input Stages Crossover Region
do, then a lower R
value may be required in order to
OUT
preserve the accuracy of the output. As an example, if the
input impedance of the driven circuit is 100 times R
The wide common mode input range is achieved with two
input stages. These two input stages consist of a pair of
matched common base PNP input transistors and a pair
of common emitter PNP input transistors. As result of
two input stages, there will be three distinct operating
regionsaroundthetransitionregionasshowninthe Input
Bias Current vs Sense Input Voltage curve in the Typical
Performance Characteristics section.
,
OUT
then the accuracy of V
will be reduced by 1% since:
OUT
ROUT •RIN(DRIVEN)
ROUT +RIN(DRIVEN)
100
VOUT = IOUT
•
= IOUT •ROUT
•
= 0.99 •IOUT •ROUT
101
The crossover voltage, the voltage where the g of one
m
Full-Scale Sense Voltage, Selection of External Input
inputstageistransferredtotheother,occursat1.6Vabove
–
Resistor, R
V . Near this region, one input stage is shutting off while
IN
theotheristurningon.Increasesintemperaturewillcause
the crossover voltage to decrease. For input operation
between 1.6V and 44V, the common base PNPs are active
(Q2, Q3 of Figure 1). The typical current through each
The external input resistor, R , controls the transconduc-
IN
tanceofthecurrentsensecircuit.SinceI
=V
/R ,
OUT
SENSE IN
transconductance g = 1/R . For example, if R =100,
m
IN
OUT
IN
thenI
IN
=V
/100orI
=1mA forV =100mV.
OUT
SENSE
SENSE
input at V
= 0V is 15μA. The input offset voltage is
SENSE
R
should be chosen to allow the required resolution
300μVmaximumatroomtemperature.Forinputoperation
between 1.6V to 0V, the other PNP is active. The current
while limiting the output current. The LT6105 can output
more than 1mA into R without introducing a signifi-
OUT
out of the inputs at V
= 0V is 100nA. The input offset
SENSE
cant increase in gain error. By setting R such that the
IN
OUT
voltage is untrimmed and is typically 300μV.
largest expected sense voltage gives I
= 1mA, then
the maximum output dynamic range is available. Output
dynamic range is limited by both the maximum allowed
output current and the maximum allowed output voltage,
as well as the minimum practical output signal. If less
Selection of External Output Resistor, R
OUT
The output resistor, R , determines how the output cur-
OUT
rent is converted to voltage. V
is simply I • R
.
OUT
RIN
OUT
dynamic range is required, then R can be increased
IN
In choosing an output resistor, the maximum output volt-
age must first be considered. If the following circuit is a
buffer or ADC with limited input range, then R
accordingly, reducing the maximum output current and
powerdissipation.TheLT6105’sperformanceisoptimized
must be
OUT
for values of R = 100Ω to 1k. Values outside this range
IN
chosen so that I
• R
is less than the allowed
OUT(MAX)
OUT
may result in additional errors. The power dissipation
maximuminputrangeofthiscircuit.Inaddition,theoutput
across R and R
should not exceed the resistors’
IN
OUT
impedance is determined by R
.
OUT
recommended ratings.
6105fa
14
LT6105
APPLICATIONS INFORMATION
Error Sources
+
Sincethecurrentexiting–INiscomingfromV ,thevoltage
+
is V – V . Taking the worst case V = 0V, the above
–IN
–IN
Thecurrentsensesystemusesanamplifier,currentmirrors
and external resistors to apply gain and level shifting. The
output is then dependent on the matching characteristics
ofthecurrentmirrors, characteristicsoftheamplifiersuch
as gain and input offset, as well as matching of external
resistors. Ideally, the circuit output is:
equation becomes:
+
P ≅ V • I
, for V < 1.6V.
–IN
IN
RIN1
The power dissipated due to internal mirrored currents:
+
P = 2 • I
• V
Q
OUT
R
RIN
The factor of 2 is the result of internal current shifting and
1:1 mirroring.
VOUT = VSENSE
•
OUT ;VSENSE = ISENSE •RSENSE
At maximum supply and maximum output current, the
total power dissipation can exceed 100mW. This will
cause significant heating of the LT6105 die. In order to
prevent damage to the LT6105, the maximum expected
dissipation in each application should be calculated. This
In this case, the only error is due to resistor mismatch,
which provides an error in gain only. Mismatch in the
internal current mirror adds to gain error but is trimmed
to less than 0.3%. Offset voltage and sense input current
are the main cause of any additional error.
number can be multiplied by the θ value listed in the Pin
JA
Configuration section to find the maximum expected die
Error Due to Input Offset Voltage
temperature. This must not be allowed to exceed 150°C,
Dynamic range is inversely proportional to the input offset
voltage.Dynamicrangecanbethoughtofasthemaximum
or performance may be degraded. As an example, if an
+
LT6105 in the MSOP package is to be run at V = 44V and
S
+
V
divided by V . The offset voltage of the LT6105
V = 36V with 1mA output current at 80°C ambient:
SENSE
OS
is typically only 100μV.
+
P
P
= 2 • I
• V = P
= 72mW
Q(MAX)
IN(MAX)
OUT(MAX)
Q(MAX)
Error Due to Sense Input Offset Current
= I
• V
= 44mW
RIN2(MAX)
+IN(MAX)
= θ • P
JA TOTAL(MAX)
Inputoffsetcurrentormismatchesininputbiascurrentwill
introduce an additional input offset voltage term. Typical
T
T
RISE
MAX
= T
+ T
RISE
AMBIENT
input offset current is 0.05μA. Lower values of R will
IN
keep this error to a minimum. For example, if R = 100Ω,
T
must be < 150°C
MAX
IN
then the additional offset is 5μV.
P
= 116mW and the maximum die temperature
TOTAL(MAX)
will be 109°C. If this same circuit must run at 125°C ambi-
Output Current Limitations Due to Power Dissipation
ent, the maximum die temperature will increase to 150°C.
Note that supply current, and therefore P , is proportional
The LT6105 can deliver up to 1mA continuous current to
Q
the output pin. This output current, I , is the mirrored
to temperature. Refer to the Typical Performance Charac-
teristics section. In this condition, the maximum output
current should be reduced to avoid device damage. The
OUT
current which flows through R and enters the current
IN2
sense amp via the +IN pin for V > 1.6V, and exits out of
–IN
–IN through R for V < 1.6V. The total power dissipa-
DCB package, on the other hand, has a lower θ and
IN1
–IN
JA
tion due to input currents, P , and the dissipation due to
subsequently, a lower die temperature increase than the
MSOP. With the same condition as above, the DCB will
rise only 7.5°C to 87.5°C and 132.5°C, respectively.
IN
internal mirrored currents, P :
Q
P
TOTAL
= P + P
IN Q
It is important to note that the LT6105 has been designed
to provide at least 1mA to the output when required, and
P = (V ) • I
; V > 1.6V
IN
+IN
RIN2 –IN
or
candelivermoreunderlargeV
conditions.Caremust
SENSE
be taken to limit the maximum output current by proper
+
P = (V – (V )) • I
; V < 1.6V
RIN1 –IN
IN
–IN
choice of sense resistor and input resistors.
6105fa
15
LT6105
APPLICATIONS INFORMATION
Output Filtering
Response Time
The output voltage, V
is simply I
• Z . This
The LT6105 is designed to exhibit fast response to inputs
forthepurposeofcircuitprotectionorsignaltransmission.
This response time will be affected by the external circuit
in two ways—delay and speed. If the output current is
very low and an input transient occurs, there may be an
increaseddelaybeforetheoutputvoltagebeginschanging.
This can be improved by increasing the minimum output
OUT
OUT
OUT
makes filtering straightforward. Any circuit may be used
which generates the required Z to get the desired filter
OUT
response. For example, a capacitor in parallel with R
OUT
will give a low pass response. This will reduce unwanted
noise from the output, and may also be useful as a charge
reservoir to keep the output steady while driving a switch-
ing circuit such as a mux or an ADC. This output capacitor
in parallel with an output resistor will create a pole in the
output response at:
current,eitherbyincreasingR
ordecreasingR .The
SENSE
IN
effect of increased output current is illustrated in the step
responsecurvesintheTypicalPerformanceCharacteristics
section of this data sheet. Note that the curves are labeled
with respect to the initial output currents. The speed is
also affected by the external circuit. In this case, if the
input changes very quickly, the internal amplifier will slew
the base of the internal output PNP (Figure 1) in order to
maintain the internal loop. This results in current flowing
1
f–3db
=
2 • π •ROUT • COUT
through R and the internal PNP. This current slew rate
IN
will be determined by the amplifier and PNP characteris-
tics as well as the input resistor, R . See the Slew Rate
IN
vs R curve in the Typical Performance Characteristics
IN
section. Using a smaller R will allow the output current
IN
to increase more quickly, decreasing the response time
at the output. This will also have the effect of increasing
the maximum output current.
TYPICAL APPLICATIONS
Gain of 20 Current Sense Amplifier with Output Filtering
2.85V TO 36V
SOURCE
0V TO 44V
+
V
LT6105
249Ω
+IN
–IN
+
V
+
–
S
V
OUT
V
= 780mV/A
0.039Ω
–
OUT
V
S
4.99k
0.22μF
249Ω
–
V
6105 TA02
TO LOAD
6105fa
16
LT6105
TYPICAL APPLICATIONS
Solenoid Monitor
mechanical system monitoring without an independent
sensor or limit switch.
The large input common mode range of the LT6105
makes it suitable for monitoring currents in quarter,
half and full bridge inductive load driving applications.
Figure 4 shows an example of a quarter bridge. The
MOSFET pulls down on the bottom of the solenoid to
increase solenoid current. It lets go to decrease current,
and the solenoid voltage freewheels around the Schottky
diode. Current measurement waveforms are shown in
Figure 5. The small glitches occur due to the action of
thesolenoidplunger, andthisprovidesanopportunityfor
Figure 6 shows another solenoid driver circuit, this time
with one end of the solenoid grounded and a P-channel
MOSFET pulling up on the other end. In this case, the
inductor freewheels around ground, imposing a negative
input common mode voltage of one Schottky diode drop.
This voltage may exceed the input range of the LT6105.
Thisdoesnotendangerthedevice,butitseverelydegrades
its accuracy. In order to avoid violating the input range,
pull-up resistors may be used as shown.
24V
DC
24V
DC
24V/OFF
24V, 3W
1Ω
1%
19V/ON
TP0610L
1N5818
SOLENOID
1Ω
1%
–
+
–
+
200Ω
1%
200Ω
1%
200Ω
1%
200Ω
1%
1N914
24V, 3W
SOLENOID
2k
1%
2k
1%
1N5818
LT6105
–IN
+IN
5V/ON
2N7000
0V/OFF
LT6105
–IN
+IN
+
V
5V
DC
+
V
5V
DC
–
V
V
OUT
= 25mV/mA
V
OUT
–
V
4.99k
1%
6105 F04
V
= 25mV/mA
V
OUT
OUT
4.99k
1%
6105 F06
Figure 4. Simplest Form of a Solenoid Driver. The LT6105
Monitors the Current in Both On and Freewheel States. The
Lowest Common Mode Voltage Is 0V, While the Highest Is
24V Plus the Forward Voltage of the Schottky Diode
Figure 6. A Similar Circuit to Figure 4, but with Solenoid
Grounded, so Freewheeling Forces Inputs Negative.
Providing Resistive Pull-Ups Keeps Amplifier Inputs From
Falling Outside of Their Accurate Input Range
5V/DIV
10V/DIV
2V/DIV
6105 F05
50ms/DIV
Figure 5. Current Measurement Waveforms. The Top Trace Is the
MOSFET Gate with High On. The Middle Trace Is the Bottom of
the Solenoid/Inductor. The Bottom Trace Is the LT6105 Output,
Representing Solenoid Current at 80mA/DIV. Glitches Are Useful
Indicators of Solenoid Plunger Movement
6105fa
17
LT6105
PACKAGE DESCRIPTION
DCB Package
6-Lead Plastic DFN (2mm × 3mm)
(Reference LTC DWG # 05-08-1715)
0.70 p 0.05
1.65 p 0.05
3.55 p 0.05
(2 SIDES)
2.15 p 0.05
PACKAGE
OUTLINE
0.25 p 0.05
0.50 BSC
1.35 p 0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.115
TYP
2.00 p 0.10
(2 SIDES)
0.40 p 0.10
R = 0.05
TYP
4
6
3.00 p 0.10 1.65 p 0.10
(2 SIDES)
(2 SIDES)
PIN 1 BAR
TOP MARK
(SEE NOTE 6)
PIN 1 NOTCH
R0.20 OR 0.25
s 45o CHAMFER
(DCB6) DFN 0405
3
1
0.25 p 0.05
0.50 BSC
0.75 p 0.05
0.200 REF
1.35 p 0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
0.00 – 0.05
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (TBD)
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 SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
6105fa
18
LT6105
PACKAGE DESCRIPTION
MS8 Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660)
0.889 p 0.127
(.035 p .005)
5.23
(.206)
MIN
3.20 – 3.45
(.126 – .136)
3.00 p 0.102
(.118 p .004)
(NOTE 3)
0.52
(.0205)
REF
0.65
(.0256)
BSC
0.42 p 0.038
(.0165 p .0015)
TYP
8
7 6
5
RECOMMENDED SOLDER PAD LAYOUT
3.00 p 0.102
(.118 p .004)
(NOTE 4)
4.90 p 0.152
(.193 p .006)
DETAIL “A”
0.254
(.010)
0o – 6o TYP
GAUGE PLANE
1
2
3
4
0.53 p 0.152
(.021 p .006)
1.10
(.043)
MAX
0.86
(.034)
REF
DETAIL “A”
0.18
(.007)
SEATING
PLANE
0.22 – 0.38
0.1016 p 0.0508
(.009 – .015)
(.004 p .002)
0.65
(.0256)
BSC
TYP
MSOP (MS8) 0307 REV F
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
6105fa
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.
19
LT6105
TYPICAL APPLICATION
Supply Monitoring
V
= 1V/A
OUT
V
OUT
LT6105
4.99k
1%
–
+
The input common mode range of the LT6105 also makes
it suitable for monitoring either positive or negative sup-
plies. Figure 7 shows one LT6105 applied as a simple
positive supply monitor, and another LT6105 as a simple
negative supply monitor. Note that the schematics are
practically identical and both have outputs conveniently
referred to ground. The only requirement for negative
supply monitoring, in addition to the usual constraints of
the absolute maximum ratings, is that the negative supply
to that LT6105 be at least as negative as the supply it is
monitoring.
–15V
V
V
5V
DC
+IN
–IN
100Ω
1%
100Ω
1%
20mΩ
1%
+
+15V
POSITIVE
SUPPLY
TO +15V
LOAD
–
CURRENT FLOW
CURRENT FLOW
–15V
NEGATIVE
SUPPLY
TO –15V
LOAD
–
20mΩ
1%
+
100Ω
1%
100Ω
1%
LT6105
–IN
+IN
+
V
5V
DC
–
V
–15V
V
= 1V/A
OUT
V
OUT
4.99k
1%
6105 F07
Figure 7. The LT6105 Can Monitor the Current of Either Positive
or Negative Supplies, Without a Schematic Change. Just Ensure
That the Current Flow Is in the Correct Direction
RELATED PARTS
PART NUMBER
LT1787/LT1787HV
LTC4150
DESCRIPTION
COMMENTS
Precision, Bidirectional, High Side Current Sense Amplifier 2.7V to 60V Operation, 75μV Offset, 60μA Current Draw
Coulomb Counter/Battery Gas Gauge
Indicates Charge Quantity and Polarity
LT6100
Gain-Selectable High Side Current Sense Amplifier
4.1V to 48V Operation, Pin-Selectable Gain: 10V/V, 12.5V/V, 20V/V,
25V/V, 40V/V, 50V/V
LTC6101/
High Voltage High Side Current Sense Amplifier
Zero Drift High Side Current Sense Amplifier
4V to 60V/5V to 100V Operation, External Resistor Set Gain, SOT23
LTC6101HV
LTC6102/
LTC6102HV
4V to 60V/5V to 100V Operation, 10μV Offset, 1μs Step Response,
MSOP8 / DFN
LTC6103
LTC6104
LT6106
Dual High Side Precision Current Sense Amplifier
Bidirectional High Side Precision Current Sense Amplifier
Low Cost, High Side Precision Current Sense Amplifier
4V to 60V, Gain Configurable, 8-Pin MSOP
4V to 60V, Gain Configurable, 8-Pin MSOP
2.7V to 36V, Gain Configurable, SOT23
6105fa
LT 0408 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
20
●
●
© LINEAR TECHNOLOGY CORPORATION 2007
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
相关型号：
LT6105CDCB#PBF
LT6105 - Precision, Rail-to-Rail Input Current Sense Amplifier; Package: DFN; Pins: 6; Temperature Range: 0°C to 70°C
ADI
LT6105HDCB#PBF
LT6105 - Precision, Rail-to-Rail Input Current Sense Amplifier; Package: DFN; Pins: 6; Temperature Range: -40°C to 125°C
ADI
LT6105HDCB#TRMPBF
LT6105 - Precision, Rail-to-Rail Input Current Sense Amplifier; Package: DFN; Pins: 6; Temperature Range: -40°C to 125°C
ADI
©2020 ICPDF网 联系我们和版权申明