INA138 [BB]
High-Side Measurement CURRENT SHUNT MONITOR; 高侧测量电流并联监视器
| 型号： | INA138 |
| 厂家： | 
BURR-BROWN CORPORATION |
| 描述： | High-Side Measurement CURRENT SHUNT MONITOR |
| 文件： | 总7页 (文件大小：72K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
®
INA138
INA168
For most current data sheet and other product
information, visit www.burr-brown.com
High-Side Measurement
CURRENT SHUNT MONITOR
DESCRIPTION
FEATURES
The INA138 and INA168 are high-side, unipolar,
current shunt monitors. Wide input common-mode
voltage range, low quiescent current, and tiny SOT-23
packaging enable use in a variety of applications.
● COMPLETE UNIPOLAR HIGH-SIDE
CURRENT MEASUREMENT CIRCUIT
● WIDE SUPPLY AND COMMON-MODE
RANGE
● INA138: 2.7V to 36V
● INA168: 2.7V to 60V
Input common-mode and power supply voltages are
independent and can range from 2.7V to 36V for the
INA138 and 2.7V to 60V for the INA168. Both
models draw only 25µA quiescent current, which also
permits connecting the power supply to either side of
the current measurement shunt with minimal error.
● INDEPENDENT SUPPLY AND INPUT
COMMON-MODE VOLTAGES
● SINGLE RESISTOR GAIN SET
● LOW QUIESCENT CURRENT (25µA typ)
● SOT23-5 Package
The device converts a differential input voltage to a
current output. This current is converted back to a
voltage with an external load resistor that sets any
gain from 1 to over 100. Although designed for
current shunt measurement, the circuit invites creative
applications in measurement and level shifting.
APPLICATIONS
● CURRENT SHUNT MEASUREMENT
Automotive, Telephone, Computers
● PORTABLE & BATTERY BACKUP
SYSTEMS
● BATTERY CHARGERS
● POWER MANAGEMENT
● CELL PHONES
Both the INA138 and INA168 are available in
SOT23-5 and are specified for the –40°C to +85°C
industrial temperature range.
● PRECISION CURRENT SOURCE
IS
RS
VIN+
3
4
VIN+
VIN–
Load
5kΩ
5kΩ
V+
5
OUT
VO = ISRSRL/5kΩ
GND
1
2
RL
International Airport Industrial Park
•
Mailing Address: PO Box 11400, Tucson, AZ 85734
•
Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706
• Tel: (520) 746-1111
Twx: 910-952-1111 Internet: http://www.burr-brown.com/
•
•
Cable: BBRCORP Telex: 066-6491
•
•
FAX: (520) 889-1510 Immediate Product Info: (800) 548-6132
•
©1999 Burr-Brown Corporation
PDS-1576A
Printed in U.S.A. December, 1999
SPECIFICATIONS
At TA = –40°C to +85°C, VS = 5V, VIN+ = 12V, ROUT = 125kΩ, unless otherwise noted.
INA138
TYP
INA168
TYP
PARAMETER
CONDITION
MIN
MAX
MIN
MAX
UNITS
INPUT
Full-Scale Sense Voltage
Common-Mode Input Range
Common-Mode Rejection
VSENSE = VI+N – VI–N
100
120
500
36
✽
✽
60
mV
V
dB
2.7
100
✽
VIN+ = 2.7V to 40V, VSENSE = 50mV
VIN+ = 2.7V to 60V, VSENSE = 50mV
100
120
✽
✽
dB
mV
µV/°C
µV/V
µV/V
uA
Offset Voltage(1)
vs Temperature
vs Power Supply
±0.2
1
0.1
±1
✽
TMIN to TMAX
V– = 2.7V to 40V, VSENSE = 50mV
V– = 2.7V to 60V, VSENSE = 50mV
VI+N, VI–N
10
0.1
✽
10
Input Bias Current
2
OUTPUT
Transconductance
vs Temperature
Nonlinearity Error
Total Output Error
Output Impedance
Voltage Output
VSENSE = 10mV – 150mV
VSENSE = 100mV
VSENSE = 10mV to 150mV
VSENSE = 100mV
198
200
10
±0.01
±0.5
1 || 5
202
✽
✽
✽
✽
✽
✽
✽
µA/V
nA/°C
%
±0.1
±2
✽
✽
%
GΩ || pF
Swing to Power Supply, V+
Swing to Common Mode, VCM
(V+) – 0.8 (V+) – 1.0
VCM – 0.5 VCM – 0.8
✽
✽
✽
✽
V
V
FREQUENCY RESPONSE
Bandwidth
ROUT = 5kΩ
ROUT = 125kΩ
5V Step, ROUT = 5kΩ
5V Step, ROUT = 125kΩ
800
32
1.8
30
✽
✽
✽
✽
kHz
kHz
µs
Settling Time (0.1%)
µs
NOISE
Output-Current Noise Density
Total Output-Current Noise
9
3
✽
✽
pA/√Hz
nA RMS
BW = 100kHz
POWER SUPPLY
Operating Range, V+
Quiescent Current
2.7
36
45
✽
60
✽
V
µA
VSENSE = 0, IO = 0
25
✽
✽
TEMPERATURE RANGE
Specification, TMIN to TMAX
Operating
Storage
Thermal Resistance
–40
–55
–65
85
125
150
✽
✽
✽
✽
✽
✽
°C
°C
°C
θJA
200
°C/W
NOTES: (1) Defined as the amount of input voltage, VSENSE, to drive the output to zero.
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2
INA138, INA168
PIN CONFIGURATION
ELECTROSTATIC
DISCHARGE SENSITIVITY
TOP VIEW
SOT
This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage.
OUT
GND
VI+N
1
2
3
5
4
V+
VI–N
ESD damage can range from subtle performance degradation
to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small parametric
changes could cause the device not to meet its published
specifications.
ABSOLUTE MAXIMUM RATINGS(1)
Supply Voltage, V+
INA138 ............................................................................... –0.3V to 60V
INA168 ............................................................................... –0.3V to 60V
Analog Inputs, VI+N, VI–N
INA138
Common Mode ............................................................... –0.3V to 40V
Differential (VI+N) – (VI–N)..................................................... –40V to 2V
INA168
Common Mode ............................................................... –0.3V to 60V
Differential (VI+N) – (VI–N)..................................................... –40V to 2V
Analog Output, Out .............................................................. –0.3V to 40V
Operating Temperature ..................................................–55°C to +125°C
Storage Temperature .....................................................–55°C to +125°C
Junction Temperature .................................................................... +150°C
Lead Temperature (soldering, 10s)............................................... +300°C
NOTE: (1) Stresses above these ratings may cause permanent damage.
Exposure to absolute maximum conditions for extended periods may degrade
device reliability. These are stress ratings only, and functional operation of the
device at these or any other conditions beyond those specified is not implied.
PACKAGE/ORDERING INFORMATION
PACKAGE
SPECIFIED
DRAWING
NUMBER
TEMPERATURE
RANGE
PACKAGE
MARKING
ORDERING
NUMBER(1)
TRANSPORT
MEDIA
PRODUCT
PACKAGE
INA138NA
SOT-23-5 Surface Mount
331
–40°C to +85°C
INA138NA/250
INA138NA/3K
Tape and Reel
Tape and Reel
"
"
"
331
"
"
"
INA168NA(2)
SOT-23-5 Surface Mount
–40°C to +85°C
INA168NA/250
INA168NA/3K
Tape and Reel
Tape and Reel
"
"
"
"
NOTE: (1) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /3K indicates 3000 devices per reel). Ordering 3000 pieces
of “INA138NA/3K” will get a single 3000-piece Tape and Reel. (2) INA168 available Q2'00.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes
no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change
without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant
any BURR-BROWN product for use in life support devices and/or systems.
®
3
INA138, INA168
TYPICAL PERFORMANCE CURVES
At TA = +25°C, V+ = 5V, VI+N = 12V, RL = 125kΩ, unless otherwise noted.
GAIN vs FREQUENCY
40
COMMON-MODE REJECTION vs FREQUENCY
120
100
80
60
40
20
0
RL = 500kΩ
G = 100
30
RL = 50kΩ
20
G = 10
G = 1
10
RL = 5kΩ
0
–10
CL = 10nF
10k
CL = 1nF CL = 100pF
100k
1M
–20
100
1k
10M
100k
70
0.1
1
10
100
1k
10k
100k
Frequency (Hz)
Frequency (Hz)
TOTAL OUTPUT ERROR vs VIN
VIN = (VI+N – VI–N
POWER-SUPPLY REJECTION vs FREQUENCY
5
0
140
120
100
80
)
–55°C
G = 100
G = 10
+150°C
–5
+25°C
G = 1
60
–10
–15
40
20
50
75
100
VIN (mV)
125
150
0
25
200
1
10
100
1k
10k
Frequency (Hz)
TOTAL OUTPUT ERROR
vs POWER-SUPPLY VOLTAGE
QUIESCENT CURRENT
vs POWER-SUPPLY VOLTAGE
2
1
50
40
30
20
10
0
Output error is essentially
independent of both
V+ supply voltage and
input common-mode voltage.
+150°
+125°
+25°
–55°
G = 1
0
G = 10
Use INA168 with
(V+) > 36V
G = 25
–1
–2
10
20
30
40
50
60
0
20
30
50
60
0
10
40
70
Power-Supply Voltage (V)
Power-Supply Voltage (V)
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4
INA138, INA168
TYPICAL PERFORMANCE CURVES (Cont.)
At TA = +25°C, V+ = 5V, VI+N = 12V, RL = 125kΩ, unless otherwise noted.
STEP RESPONSE
STEP RESPONSE
200mV
G = 1
G = 25
0V
1V/div
100mV
50mV/div
100mV
G = 1
0mV
G = 10
0V
500mV/div
10µs/div
10µs/div
®
5
INA138, INA168
BASIC CONNECTION
OPERATION
Figure 1 shows the basic connection of the INA138. The
input pins, VI+N and VI–N, should be connected as closely as
possible to the shunt resistor to minimize any resistance in
series with the shunt resistance. The output resistor, RL, is
shown connected between pin 1 and ground. Best accuracy
is achieved with the output voltage measured directly across
RL. This is especially important in high-current systems
where load current could flow in the ground connections,
affecting the measurement accuracy.
Figure 1 shows the basic circuit diagram for both the
INA138 and INA168. Load current, IS, is drawn from
supply, VS, through shunt resistor, Rs. The voltage drop in
the shunt resistor, VS, is forced across Rg1 by the internal
op-amp, causing current to flow into the collector of Q1.
External resistor, RL, converts the output current to a volt-
age, VOUT, at the Out pin.
The transfer function for the INA138 is:
No power supply bypass capacitors are required for stability
of the INA138. However, applications with noisy or high
impedance power supplies may require de-coupling capaci-
tors to reject power supply noise. Connect bypass capacitors
close to the device pins.
IO = gm (VI+N – VI–N)
(1)
(2)
where gm = 200µA/V
In the circuit of Figure 1, the input voltage, (VI+N – VI–N), is
equal to IS • RS and the output voltage, VOUT, is equal to
IO • RL. The transconductance, gm, of the INA138 is
200µA/V. The complete transfer function for the current
measurement amplifier in this application is:
POWER SUPPLIES
The input circuitry of the INA138 can accurately measure
beyond its power supply voltage, V+. For example, the V+
power supply can be 5V while the load power supply is
voltage is up to +36V (or +60V with INA168). However, the
output voltage range of the Out terminal is limited by the
lesser of the two voltages (see “Output Voltage Range”).
VOUT = (IS) (RS) (200µA/V) (RL)
(3)
The maximum differential input voltage for accurate mea-
surements is 0.5V, which produces a 100µA output current.
A differential input voltage of up to 2V will not cause
damage. Differential measurements (pins 3 and 4) must be
unipolar with a more-positive voltage applied to pin 3. If a
more-negative voltage is applied to pin 3, the output current,
IO, will be zero, but it will not cause damage.
SELECTING RS AND RL
The value chosen for the shunt resistor, RS, depends on the
application and is a compromise between small-signal accu-
racy and maximum permissible voltage loss in the measure-
ment line. High values of RS provide better accuracy at
VP
Load Power Supply
+2.7 to 36V(1)
Shunt
RS
IS
VIN+
VI–N
V+ power can be
common or
indepedent of
3
4
Load
V+
load supply.
RG1
5kΩ
RG2
5kΩ
2.7 ≤ (V+) ≤ 36V(1)
5
Q1
OUT
1
INA138
VOLTAGE GAIN
EXACT RL (Ω)
NEAREST 1% RL (Ω)
+
VO
–
2
I0
1
2
5k
4.99k
10k
RL
10k
5
25k
24.9k
49.9k
100k
249k
499k
10
20
50
100
50k
100k
250k
500k
NOTE: (1) Maximum VP and V+ voltage is 60V with INA168.
FIGURE 1. Basic Circuit Connections.
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6
INA138, INA168
lower currents by minimizing the effects of offset, while low
values of RS minimize voltage loss in the supply line. For
most applications, best performance is attained with an RS
value that provides a full-scale shunt voltage of 50mV to
100mV. Maximum input voltage for accurate measurements
is 500mV.
output swing. The maximum output voltage compliance is
limited by the lower of the two equations below:
Vout max = (V+) – 0.7V – (VI+N – VI–N)
or
(4)
(5)
Vout max = VI–N – 0.5V
(whichever is lower)
RL is chosen to provide the desired full-scale output voltage.
The output impedance of the INA138 Out terminal is very
high which permits using values of RL up to 500kΩ with
excellent accuracy. The input impedance of any additional
circuitry at the output should be much higher than the value
of RL to avoid degrading accuracy.
BANDWIDTH
Measurement bandwidth is affected by the value of the load
resistor, RL. High gain produced by high values of RL will
yield a narrower measurement bandwidth (see Typical Per-
formance Curves). For widest possible bandwidth, keep the
capacitive load on the output to a minimum. Reduction in
bandwidth due to capacitive load is shown in the Typical
Performance Curves.
Some A/D converters have input impedances that will sig-
nificantly affect measurement gain. The input impedance of
the A/D converter can be included as part of the effective RL
if its input can be modeled as a resistor to ground. Alterna-
tively, an op-amp can be used to buffer the A/D converter
input. See Figure 1 for recommended values of RL.
If bandwidth limiting (filtering) is desired, a capacitor can be
added to the output, as shown in Figure 3. This will not
cause instability.
OUTPUT VOLTAGE RANGE
The output of the INA138 is a current, which is converted to
a voltage by the load resistor, RL. The output current remains
accurate within the compliance voltage range of the output
circuitry. The shunt voltage and the input common-mode
and power supply voltages limit the maximum possible
APPLICATIONS
The INA138 is designed for current shunt measurement
circuits as shown in Figure 1, but its basic function is useful
in a wide range of circuitry. A creative engineer will find
many unforeseen uses in measurement and level shifting
circuits. A few ideas are shown.
IS
3
4
3
4
f–3dB
INA138
ZIN
1
OPA340
f–3dB
=
INA138
2πRLCL
VO
RL
Buffer of amp drives A/D converter
without affecting gain.
CL
RL
FIGURE 3. Output Filter.
FIGURE 2. Buffering Output to Drive A/D Converter.
3
3
4
4
V+
V+
REF200
100µA
INA138
INA138
R1
R2
V0
V0
1
1
RL
Gain Set by R1//R2
(V+)R2
Gain Set by RL
Output Offset = (100µA)(RL)
Output Offset =
(independent of V+)
R1+R2
a). Using resistor divider.
b). Using current source.
FIGURE 4. Offsetting the Output Voltage.
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INA138, INA168
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