LTC6103
Dual High Voltage, High Side
Current Sense Amplifier
FEATURES
DESCRIPTION
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The LTC®6103 is a versatile, high voltage, high side, dual
current sense amplifier. The two internal amplifiers are
independent except that they share the same V– terminal.
Design flexibility is provided by the excellent device characteristics: 450µV maximum offset, and only 275µA of
current consumption (typical at 12V) for each amplifier.
The LTC6103 operates on supplies from 4V to 60V.
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Two Independent Current Sense Amplifiers
Wide Supply Range: 4V to 60V, 70V Absolute
Maximum
Low Offset Voltage: 450µV Maximum
Fast Response: 1µs Response Time
Gain Configurable with External Resistors
Low Input Bias Current: 170nA Maximum
PSRR: 110dB Minimum (6V to 60V)
Output Current: 1mA Maximum
Low Supply Current: 275µA per Amplifier, VS = 12V
Specified for –40°C to 125°C Temperature Range
Available in an 8-lead MSOP Package
The LTC6103 monitors current via the voltage across an
external sense resistor (shunt resistor). Internal circuitry
converts input voltage to output current, allowing for a
small sense signal on a high common mode voltage to be
translated into a ground referenced signal. Low DC offset allows the use of a small shunt resistor and large gain-setting
resistors. As a result, power loss in the shunt is minimal.
APPLICATIONS
■
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Current Shunt Measurement
Battery Monitoring
Remote Sensing
Power Management
High Voltage Level Translator
The wide operating supply range and high accuracy make
the LTC6103 ideal for an extensive variety of applications
from automotive to industrial and power management.
The fast response makes the LTC6103 the perfect choice
for load current warnings and shutoff protection control.
With very low supply current, the LTC6103 is suitable for
power sensitive applications.
The LTC6103 is available in an 8-lead MSOP package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Two 16-Bit Current Sense Channels Connected Directly to the LTC2436-1 ADC
VA+
VSENSE
ILOAD
–
VB+
VSENSE
+
LOAD
+
7
+INA
–
6
–INA
2
VSB
OUTA
V
1
4
6
1
CH1
OUTB
2
LTC2436-1
4
ROUT
4.99k
IOUT = 100µA
13
7
–
5
ROUT
4.99k
5.5V
5V
5V 1µF
+INB
– +
VSA
LTC6103
∆VSENSE– = 100mV
5
–INB
+ –
VSENSE–
LOAD
RIN
100Ω
RIN
100Ω
8
Step Response
ILOAD
12
TO µP
11
CH0
0.5V
0V
VOUT
IOUT = 0µA
500ns/DIV
TA = 25°C
V+ = 12V
RIN = 100Ω
ROUT = 5k
VSENSE+ = V+
6103 TA01b
3,8,9,10,14,15,16
6103 TA01a
6103f
1
LTC6103
ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER INFORMATION
(Note 1)
Total Supply Voltage (+INA/+INB to V–) ....................70V
Maximum Applied Output Voltage (OUTA/OUTB) ........9V
Input Current........................................................±10mA
Output Short-Circuit Duration (to V–)............... Indefinite
Operating Temperature Range
LTC6103C ............................................ –40°C to 85°C
LTC6103I ............................................. –40°C to 85°C
LTC6103H .......................................... –40°C to 125°C
Specified Temperature Range (Note 2)
LTC6103C ................................................ 0°C to 70°C
LTC6103I ............................................. –40°C to 85°C
LTC6103H .......................................... –40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
TOP VIEW
OUTA
OUTB
NC
V–
1
2
3
4
8
7
6
5
+INA
–INA
–INB
+INB
MS8 PACKAGE
8-LEAD PLASTIC MSOP
TJMAX = 150°C, θJA = 300°C/W
ORDER PART NUMBER
MS8 PART MARKING*
LTC6103CMS8
LTC6103IMS8
LTC6103HMS8
LTCMN
LTCMN
LTCMN
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
*The temperature grade is identified by a label on the shipping container.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. RIN = 100Ω, ROUT = 5k, 4V ≤ +INA/+INB ≤ 60V, V– = 0V unless otherwise
noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
●
+INA(VSA)/
+INB(VSB)
Supply Voltage Range
VOS
Input Offset Voltage
VSENSE = 5mV, LTC6103
VSENSE = 5mV, LTC6103C, LTC6103I
VSENSE = 5mV, LTC6103H
●
●
ΔVOS/ΔT
Input Offset Voltage Drift
VSENSE = 5mV
●
IB
Input Bias Current
RIN = 1M to –INA and –INB
PSRR
Power Supply Rejection Ratio
+INA/+INB = 6V to 60V, VSENSE = 5mV
+INA/+INB = 4V to 60V, VSENSE = 5mV
TYP
4
±85
MAX
60
V
±450
±600
±700
µV
µV
µV
±1.5
100
●
UNITS
µV/°C
170
245
nA
nA
●
110
106
120
dB
dB
●
105
98
115
dB
dB
8
3
1
VOUT(MAX)
Maximum Output Voltage
12V ≤ +INA/+INB ≤ 60V, VSENSE = 88mV, ROUT = 10k
+INA/+INB = 6V, VSENSE = 66mV, ROUT = 5k
+INA/+INB = 4V, VSENSE = 55mV, ROUT = 2k
●
●
●
VOUT(O)
Minimum Output Voltage
(Note 3)
VSENSE = 0V, LTC6103
VSENSE = 0V, LTC6103C, LTC6103I
VSENSE = 0V, LTC6103H
●
●
IOUT(MAX)
Maximum Output Current
6V ≤ +INA/+INB ≤ 60V, VSENSE = 110mV, ROUT = 2k
+INA/+INB = 4V, VSENSE = 55mV, ROUT = 2k, Gain = 20
●
●
tr
Input Step Response
(to 50% of Output Step)
ΔVSENSE = 100mV Step, 6V ≤ +INA/+INB ≤ 60V
+INA/+INB = 4V (1V Output Step), ROUT = 1k
1
1.5
µs
µs
BW
Signal Bandwidth
IOUT = 200µA, RIN = 100Ω, ROUT = 5k
IOUT = 1mA, RIN = 100Ω, ROUT = 5k
120
140
kHz
kHz
V
V
V
0
1
0.5
22.5
30
35
mV
mV
mV
mA
mA
6103f
2
LTC6103
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. RIN = 100Ω, ROUT = 5k, 4V ≤ +INA/+INB ≤ 60V, V– = 0V unless otherwise
noted.
SYMBOL
PARAMETER
CONDITIONS
I+INA, I+INB
Supply Current per Amplifier
+INA/+INB = 4V, IOUT = 0, RIN = 1M
MIN
●
+INA/+INB = 6V, IOUT = 0, RIN = 1M
●
+INA/+INB = 12V, IOUT = 0, RIN = 1M
●
+INA/+INB = 60V, IOUT = 0, RIN = 1M
LTC6103I, LTC6103C
LTC6103H
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: The LTC6103C is guaranteed to meet specified performance
from 0°C to 70°C. The LTC6103C is designed, characterized and
●
●
TYP
MAX
UNITS
220
450
475
µA
µA
255
475
525
µA
µA
275
500
590
µA
µA
390
640
690
720
µA
µA
µA
expected to meet specified performance from –40°C to 85°C but is not
tested or QA sampled at these temperatures. LTC6103I is guaranteed
to meet specified performance from –40°C to 85°C. The LTC6103H is
guaranteed to meet specified performance from –40°C to 125°C.
Note 3: This parameter is not tested in production and is guaranteed
by the VOS test.
TYPICAL PERFORMANCE CHARACTERISTICS
Input VOS vs Temperature
Input VOS vs Supply Voltage
3 REPRESENTATIVE UNITS
50
0
–50
–100
RIN = 100Ω
ROUT = 5k
VIN = 5mV
0
20 40 60 80
TEMPERATURE (°C)
100 120
6103 G01
INPUT OFFSET VOLTAGE (µV)
INPUT OFFSET VOLTAGE (µV)
100
–200
–40 –20
5.0
150
150
–150
Input Sense Range
200
TA = 85°C
RIN = 5k
4.5 ROUT = 2.5k
TA = 125°C
100
MAXIMUM VSENSE (V)
200
50
TA = 45°C
0
TA = 0°C
–50
TA = –40°C
–100
3.5
3.0
2.5
2.0
RIN = 100Ω
ROUT = 5k
VIN = 5mV
–150
–200
4.0
0
10
20
40
50
30
VSUPPLY AT +INA OR +INB (V)
60
1.5
1.0
4
5
6
7
8
9
10
11
12
V+ (V)
6103 G02
6103 G03
6103f
3
LTC6103
TYPICAL PERFORMANCE CHARACTERISTICS
VOUT Maximum vs Temperature
MAXIMUM IOUT (mA)
VS = 12V
8
6
VS = 6V
4
VS = 4V
2
TA = 25°C
GAIN =10
VS = 12V
6
10
10
5
VS = 60V
OUTPUT ERROR (%)
VS = 60V
MAXIMUM OUTPUT (V)
100
7
12
4
VS = 6V
3
VS = 4V
2
1
0.1
1
0
–40 –20
0
20 40 60 80
TEMPERATURE (°C)
0.01
0
–40 –20
100 120
0
20 40 60 80
TEMPERATURE (°C)
100 120
6103 G04
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
INPUT VOLTAGE (V)
6103 G06
6103 G05
Gain vs Frequency
Input Bias Current vs Temperature
Supply Current vs Supply Voltage
450
35
140
400
120
IOUT = 1mA
25
20
VS = 4V
80
15
60
10
40
TA = 25°C
5 RIN = 100Ω
ROUT = 5k
0
1k
100k
10k
INPUT FREQUENCY (Hz)
VS = 6V TO 100V
100
IB (nA)
IOUT = 200µA
SUPPLY CURRENT (µA)
40
160
30
GAIN (dB)
Calculated Output Error Due to
Input Offset vs Input Voltage
IOUT Maximum vs Temperature
20
1M
0
20 40 60 80
TEMPERATURE (°C)
100 120
250
TA = 25°C
200
TA = –40°C
TA = 0°C
150
100
VIN = 0V
RIN = 1M
0
0
20
30
10
40
50
VSUPPLY AT +INA OR +INB (V)
6103 G09
Step Response 0mV to 10mV
60
6103 G10
Step Response 10mV to 20mV
VSENSE–
V+-10mV
VSENSE–
+
V -20mV
0.5V
0V
350
300
50
0
–40 –20
6103 G08
V+
+
V -10mV
TA = 125°C
TA = 85°C
TA = 70°C
TA = 25°C
V+ = 12V
RIN = 100Ω
ROUT = 5k
VSENSE+ = V+
1V
0.5V
VOUT
TA = 25°C
V+ = 12V
RIN = 100Ω
ROUT = 5k
VSENSE+ = V+
VOUT
TIME (10µs/DIV)
TIME (10µs/DIV)
6103 G11
6103 G12
6103f
4
LTC6103
TYPICAL PERFORMANCE CHARACTERISTICS
Step Response 0mV to 100mV
VSENSE
Step Response 0mV to 100mV
–
V+
∆VSENSE– =100mV
5V
CLOAD = 10pF
VSENSE
Step Response Rising Edge
–
VSENSE–
∆VSENSE– =100mV
5V
CLOAD = 1000pF
TA = 25°C
V+ = 12V
CLOAD = 2200pF
RIN = 100Ω
ROUT = 5k
VSENSE+ = V+
∆VSENSE– =100mV
5.5V
5V
TA = 25°C
V+ = 12V
RIN = 100Ω
ROUT = 5k
VSENSE+ = V+
VOUT
IOUT = 100µA
0V
VOUT
TIME (10µs/DIV)
0.5V
0V
VOUT
TIME (100µs/DIV)
IOUT = 0µA
TIME (500ns/DIV)
6103 G14
6103 G13
Step Response Falling Edge
6103 G15
PSRR vs Frequency
140
V+
5.5V
5V
∆VSENSE– =100mV
120
VOUT
100
TA = 25°C
V+ = 12V
RIN = 100Ω
ROUT = 5k
VSENSE+ = V+
IOUT = 0µA
IOUT = 100µA
0.5V
0V
TIME (500ns/DIV)
6103 G16
PSRR (dB)
0V
TA = 25°C
V+ = 12V
RIN = 100Ω
ROUT = 5k
VSENSE+ = V+
VS = 12V
80
VS = 4V
60
RIN = 100Ω
40 ROUT = 5k
COUT = 5pF
20 GAIN = 50
IOUTDC = 100µA
VINAC = 50mVP-P
0
0.1
1
10 100 1k
10k
FREQUENCY (Hz)
100k
1M
6103 G17
6103f
5
LTC6103
PIN FUNCTIONS
OUTA (Pin 1): Current Output of Amplifier A. OUTA will
source a current that is proportional to the sense voltage
of amplifier A into an external resistor.
–INB (Pin 6): The Negative Input of the Internal Sense
Amplifier B. The internal sense amplifier will drive –INB
to the same potential as +INB. A resistor (RIN) tied from
VB+ to –INB sets the output current IOUT = VSENSE/ RIN.
VSENSE is the voltage developed across the external RSENSE
(Figure 1).
OUTB (Pin 2): Current Output of Amplifier B. OUTB will
source a current that is proportional to the sense voltage
of amplifier B into an external resistor.
–INA (Pin 7): The Negative Input of the Internal Sense
Amplifier A. The internal sense amplifier will drive –INA
to the same potential as +INA. A resistor (RIN) tied from
VA+ to –INA sets the output current IOUT = VSENSE/ RIN.
VSENSE is the voltage developed across the external RSENSE
(Figure 1).
NC (Pin 3): No Connect.
V– (Pin 4): Negative Supply (or Ground for Single Supply
Operation). Common to both amplifiers.
+INB/VSB (Pin 5): The Positive Input of the Internal Sense
Amplifier B. Must be tied to the system load end of the
sense resistor. It also works as the positive supply for
amplifier B. Supply current of amplifier B is drawn through
this pin. The LTC6103 supply current is monitored along
with the system load current.
+INA/VSA (Pin 8): The Positive Input of the Internal Sense
Amplifier A. Must be tied to the system load end of the
sense resistor. It also works as the positive supply for
amplifier A. Supply current of amplifier A is drawn through
this pin. The LTC6103 supply current is monitored along
with the system load current.
BLOCK DIAGRAM
VA+
ILOAD
VSENSE
VSENSE
RSENSE
RSENSE
–
LOAD
VB+
+
+
RIN
8
6
–INA
5
–INB
5k 5k
ISA
LOAD
RIN
7
+INA
ILOAD
–
+INB
5k 5k
+ –
– +
VSA
ISB
VSB
10V
10V
V–
OUTA
1
4
OUTB
2
6103 F01
IOUT
ROUT
IOUT
VOUT = VSENSE •
ROUT
ROUT
RIN
Figure 1. LTC6103 Block Diagram and Typical Connection
6103f
6
LTC6103
THEORY OF OPERATION
An internal sense amplifier loop forces –IN to have the
same potential as +IN. Connecting an external resistor, RIN,
between –IN and V+ forces a potential across RIN that is the
same as the sense voltage across RSENSE. A corresponding
current, (ILOAD + IS) • RSENSE/RIN, will flow through RIN.
The high impedance inputs of the sense amplifier will not
conduct this input current, so the current will flow through
an internal MOSFET to the OUT pin. In most application
cases, IS 1.2A)
BAT54C
VLOGIC
R5
7.5k
6103 F03b
(VLOGIC + 5V) ≤ VIN ≤ 60V
0A ≤ ILOAD ≤ 10A
LOW CURRENT
RANGE OUT
250mV/A
Figure 3b. The LTC6103 Allows High-Low Current Ranging
Care should be taken when designing the printed circuit
board layout to minimize input trace resistance (to Pins 5,
6, 7 and 8), especially for small RIN values. Trace resistance
to the –IN terminals will increase the effective RIN value,
causing a gain error. Trace resistance on +IN terminals will
have an effect on offset error. These errors are described
in more detail later in this data sheet. In addition, internal
device resistance will add approximately 0.3Ω to RIN.
Selection of External Output Resistor, ROUT
The output resistor, ROUT, determines how the output current is converted to voltage. VOUT is simply IOUT • ROUT. In
choosing an output resistor, the maximum output voltage
must first be considered. If the circuit following is a buffer or ADC with limited input range, then ROUT must be
chosen so that IOUT(MAX) • ROUT is less than the allowed
maximum input range of this circuit.
In addition, the output impedance is determined by ROUT. If
the circuit to be driven has high enough input impedance,
then almost any useful output impedance will be acceptable. However, if the driven circuit has relatively low input
impedance or draws spikes of current, as an ADC might
do, then a lower ROUT value may be required in order to
preserve the accuracy of the output. As an example, if the
input impedance of the driven circuit is 100 times ROUT,
then the accuracy of VOUT will be reduced by 1% since:
VOUT = IOUT •
ROUT • RIN(DRIVEN)
ROUT + RIN(DRIVEN)
= IOUT • ROUT •
100
= 0.99 • IOUT • ROUT
101
6103f
9
LTC6103
APPLICATIONS INFORMATION
Error Sources
The current sense system uses an amplifier and resistors
to apply gain and level shift the result. The output is then
dependent on the characteristics of the amplifier, such as
bias current and input offset, as well as resistor matching.
Ideally, the circuit output is:
VOUT = VSENSE •
ROUT
RIN
VSENSE = RSENSE • ISENSE
supply current can cause an output error if trace resistance
between RSENSE and +IN is significant (Figure 4).
EOUT(RT_+IN) = (IS • RT/RIN) • ROUT
Trace resistance to the –IN pin will increase the effective
RIN value, causing a gain error. In addition, internal device
resistance will add approximately 0.3Ω to RIN.
Minimizing the trace resistance is important and care
should be taken in the PCB layout. Make the trace short
and wide. Kelvin connection to the shunt resistor pad
should be used.
In this case, the only error is due to resistor mismatch,
which provides an error in gain only. However, offset
voltage, bias current and finite gain in the amplifier cause
additional errors.
V+
ILOAD
RSENSE
LOAD
RIN
Output Error, EOUT, Due to the Amplifier DC Offset
Voltage, VOS
EOUT( VOS) = VOS •
ROUT
RIN
IS
Since IB(+) ≈ IB(–) = IBIAS, if RSENSE
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