ETC XTR116U/2K5

®
XTR115
XTR116
XTR
116
XTR
115
For most current data sheet and other product
information, visit www.burr-brown.com
4-20mA CURRENT LOOP TRANSMITTERS
FEATURES
APPLICATIONS
● LOW QUIESCENT CURRENT: 200µA
● 2-WIRE, 4-20mA CURRENT LOOP
TRANSMITTER
● 5V REGULATOR FOR EXTERNAL CIRCUITS
● VREF FOR SENSOR EXCITATION:
● SMART TRANSMITTER
● INDUSTRIAL PROCESS CONTROL
XTR115: 2.5V
XTR116: 4.096V
● LOW SPAN ERROR: 0.05%
● TEST SYSTEMS
● COMPATIBLE WITH HART MODEM
● LOW NONLINEARITY ERROR: 0.003%
● WIDE LOOP SUPPLY RANGE: 7.5V to 36V
● CURRENT AMPLIFIER
● VOLTAGE-TO-CURRENT AMPLIFIER
● SO-8 PACKAGE
DESCRIPTION
used for offsetting or to excite transducers. A current
return pin (IRET) senses any current used in external
circuitry to assure an accurate control of the output
current.
The XTR115 is a fundamental building block of
smart sensors using 4-to-20mA current transmission.
The XTR115 and XTR116 are precision current output converters designed to transmit analog 4-to-20mA
signals over an industry standard current loop. They
provide accurate current scaling and output current
limit functions.
The XTR115 and XTR116 are specified for operation over the extended industrial temperature range,
–40°C to +85°C.
The on-chip voltage regulator (5V) can be used to
power external circuitry. A precision on-chip VREF
(2.5V for XTR115 and 4.096V for XTR116) can be
XTR115
XTR116
VREG
+5V
+5V
Regulator
8
VREF
XTR115: 2.5V
XTR116: 4.096V
1
V+
7
Voltage
Reference
VLOOP
RIN
B
6
IIN
2
+
RL
A1
E
5
VIN
–
RLIM
3
IRET
R1
2.475kΩ
R2
25Ω
IO =
100 VIN
RIN
4
I = 100 • IIN
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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
®
©
SBOS124
2000 Burr-Brown Corporation
PDS-1582A
1
in U.S.A. January, 2000
XTR115,Printed
XTR116
SPECIFICATIONS
At TA = +25°C, V+ = 24V, RIN = 20kΩ, and TIP29C external transistor, unless otherwise noted.
XTR115U
XTR116U
PARAMETER
CONDITIONS
OUTPUT
Output Current Equation
Output Current, Linear Range
Over-Scale Limit
Under-Scale Limit
SPAN
Span (Current Gain)
Error (1)
vs Temperature
Nonlinearity
INPUT
Offset Voltage (Op Amp)
vs Temperature
vs Supply Voltage, V+
Bias Current
vs Temperature
Noise: 0.1Hz to 10Hz
IREG = 0, IREF = 0
32
0.2
IIN = 250µA to 25mA
TA = –40°C to +85°C
IIN = 250µA to 25mA
100
±0.05
±3
±0.003
ILIM
IMIN
S
VOS
MIN
25
✻
TYP
MAX
UNITS
✻
0.25
✻
✻
✻
mA
mA
mA
±0.2
±20
±0.01
✻
✻
✻
✻
±0.4
✻
±0.02
A/A
%
ppm/°C
%
IIN = 40µA
TA = –40°C to +85°C
V+ = 7.5V to 36V
±100
±0.7
±0.1
–35
150
0.6
CLOOP = 0, R L = 0
380
3.2
✻
✻
kHz
mA/µs
2.5
4.096
±0.05
±20
±1
±100
10
16
✻
✻
✻
✻
✻
✻
✻
✻
V
V
%
ppm/°C
ppm/V
ppm/mA
µVp-p
mA
IB
en
IREF = 0
TA = –40°C to +85°C
V+ = 7.5V to 36V
IREF = 0mA to 2.5mA
VREG(2)
Voltage
Voltage Accuracy
vs Temperature
vs Supply Voltage, V+
vs Output Current
Short-Circuit Current
MAX
✻
0.25
VREF(2)
XTR115
XTR116
Voltage Accuracy
vs Temperature
vs Supply Voltage, V+
vs Load
Noise: 0.1Hz to 10Hz
Short-Circuit Current
TEMPERATURE RANGE
Specification
Operating
Storage
Thermal Resistance
TYP
IO = IIN • 100
IO
DYNAMIC RESPONSE
Small Signal Bandwidth
Slew Rate
POWER SUPPLY
Specified
Voltage Range
Quiescent Current
Over Temperature, –40°C to +85°C
MIN
XTR115UA
XTR116UA
±250
±3
±2
✻
✻
✻
✻
✻
✻
±0.25
±35
±10
✻
✻
✻
✻
5
±0.05
±0.1
±0.1
1
See Typical Curves
12
IREG = 0
TA = –40°C to +85°C
V+ = 7.5V to 36V
±500
±6
✻
±0.5
±75
✻
✻
✻
µV
µV/°C
µV/V
nA
pA/°C
µVp-p
V
V
mV/°C
mV/V
mA
V+
✻
+24
+7.5
200
240
–40
–55
–55
θJA
150
✻ Specifications the same as XTR115U and XTR116U.
NOTES: (1) Does not include initial error or TCR of RIN. (2) Voltage measured with respect to IRET pin.
®
XTR115, XTR116
2
+36
250
300
✻
+85
+125
+125
✻
✻
✻
✻
✻
✻
✻
✻
✻
✻
✻
✻
V
V
µA
µA
°C
°C
°C
°C/W
ABSOLUTE MAXIMUM RATINGS(1)
PIN CONFIGURATION
Top View
Power Supply, V+ (referenced to IO pin) .......................................... 40V
Input Voltage (referenced to IRET pin) ........................................ 0V to V+
Output Current Limit ............................................................... Continuous
VREG, Short-Circuit .................................................................. Continuous
VREF, Short-Circuit .................................................................. Continuous
Operating Temperature ................................................ –55°C to +125°C
Storage Temperature Range ....................................... –55°C to +125°C
Lead Temperature (soldering, 10s) .............................................. +300°C
Junction Temperature ................................................................... +165°C
SO-8
VREF
1
8
VREG
IIN
2
7
V+
IRET
3
6
B (Base)
IO
4
5
E (Emitter)
NOTE: (1) Stresses above these ratings may cause permanent damage.
Exposure to absolute maximum conditions for extended periods may degrade
device reliability.
ELECTROSTATIC
DISCHARGE SENSITIVITY
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.
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.
PACKAGE/ORDERING INFORMATION
PRODUCT
PACKAGE
PACKAGE
DRAWING
NUMBER
XTR115UA
SO-8
182
–40°C to +85°C
XTR115UA
XTR115UA
Rails
"
"
"
"
XTR115UA/2K5
Tape and Reel
SO-8
182
–40°C to +85°C
XTR115U
"
"
"
"
XTR115U
XTR115U/2K5
Rails
Tape and Reel
SO-8
182
–40°C to +85°C
XTR116UA
"
"
"
"
XTR116UA
XTR116UA/2K5
Rails
Tape and Reel
SO-8
182
–40°C to +85°C
XTR116U
XTR116U
Rails
"
"
"
"
XTR116U/2K5
Tape and Reel
"
XTR115U
"
XTR116UA
"
XTR116U
"
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
MARKING
ORDERING
NUMBER(1)
TRANSPORT
MEDIA
NOTES: (1) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces
of “XTR115UA/2K5” will get a single 2500-piece Tape and Reel.
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
XTR115, XTR116
TYPICAL PERFORMANCE CURVES
At TA = +25°C, V+ = 24V, RIN = 20kΩ, and TIP29C external transistor, unless otherwise noted.
CURRENT GAIN vs FREQUENCY
QUIESCENT CURRENT vs TEMPERATURE
260
Quiescent Current (µA)
Gain (dB)
40
COUT = 0
RL = 0Ω
30
COUT = 10nF
RL = 250Ω
20
10
240
(V+) = 36V
220
(V+) = 24V
200
(V+) = 7.5V
180
160
10k
100k
1M
–75
–50
–25
0
Frequency (Hz)
25
50
75
100
125
Temperature (°C)
REFERENCE VOLTAGE vs TEMPERATURE
OVER-SCALE CURRENT vs TEMPERATURE
0.1
34
Over-Scale Current (mA)
∆ Reference Voltage (%)
With External Transistor
0
–0.1
–0.2
33
32
V+ = 36V
31
V+ = 7.5V
30
V+ = 24V
29
–0.3
28
–75
–50
–25
0
25
50
75
100
125
–75
Temperature (°C)
+125°C
VREG Voltage (V)
–55°C
+25°C
–55°C
5.0
+25°C
Sinking
Current
Sourcing
Current
+125°C
4.5
–1
0
1
2
3
4
IREG Current (mA)
®
XTR115, XTR116
–25
0
25
50
Temperature (°C)
VREG VOLTAGE vs VREG CURRENT
5.5
–50
4
75
100
125
APPLICATIONS INFORMATION
and upward. Full-scale inputs greater than 0.5V are recommend to minimize the effect of offset voltage and drift of A1.
The XTR115 and XTR116 are identical devices except for
the reference voltage output, pin 1. This voltage is available
for external circuitry and is not used internally. Further
discussions that apply to both devices will refer to the
“XTR115/6.”
EXTERNAL TRANSISTOR
The external transistor, Q1, conducts the majority of the fullscale output current. Power dissipation in this transistor can
approach 0.8W with high loop voltage (40V) and 20mA
output current. The XTR115/6 is designed to use an external
transistor to avoid on-chip thermal-induced errors. Heat
produced by Q1 will still cause ambient temperature changes
that can affect the XTR115/6. To minimize these effects,
locate Q1 away from sensitive analog circuitry, including
XTR115/6. Mount Q1 so that heat is conducted to the
outside of the transducer housing.
Figure 1 shows basic circuit connections with representative
simplified input circuitry. The XTR115/6 is a two-wire
current transmitter. Its input signal (pin 2) controls the output
current. A portion of this current flows into the V+ power
supply, pin 7. The remaining current flows in Q1. External
input circuitry connected to the XTR115/6 can be powered
from VREG or VREF. Current drawn from these terminals
must be returned to IRET, pin 3. This IRET pin is a “local
ground” for input circuitry driving the XTR115/6.
The XTR115/6 is designed to use virtually any NPN transistor with sufficient voltage, current and power rating. Case
style and thermal mounting considerations often influence
the choice for any given application. Several possible choices
are listed in Figure 1. A MOSFET transistor will not improve
the accuracy of the XTR115/6 and is not recommended.
The XTR115/6 is a current-input device with a gain of 100.
A current flowing into pin 2 produces IO = 100 • IIN. The
input voltage at the IIN pin is zero (referred to the IRET pin).
A voltage input is created with an external input resistor, as
shown. Common full-scale input voltages range from 1V
XTR115
XTR116
IREG
5V
XTR115: 2.5V
XTR116: 4.096V
IO
VREG
+5V
Regulator
8
IREF
VREF
1
V+
7
Voltage
Reference
VLOOP
Input
Circuitry
VIN
RIN
20kΩ
IIN
B
IIN
2
6
Q1
10nF
RL
A1
E
5
RLIM
3
All return current
from IREG and IREF
IRET
R1
2.475kΩ
R2
25Ω
IO
4
I = 100 • IIN
For IO = 4mA to 20mA
IIN = 40µA to 200µA
With RIN = 20kΩ
VIN = 0.8V to 4V
Possible choices for Q1 (see text).
TYPE
PACKAGE
2N4922
TIP29C
TIP31B
TO-225
TO-220
TO-220
FIGURE 1. Basic Circuit Connections.
®
5
XTR115, XTR116
MINIMUM-SCALE CURRENT
MAXIMUM OUTPUT CURRENT
The quiescent current of the XTR115/6 (typically 200µA)
is the lower limit of its output current. Zero input current
(IIN = 0) will produce an IO equal to the quiescent current.
Output current will not begin to increase until IIN > IQ /100.
Current drawn from VREF or VREG will add to this minimum
output current. This means that more than 3.7mA is available to power external circuitry while still allowing the
output current to go below 4mA.
The XTR115/6 provides accurate, linear output up to 25mA.
Internal circuitry limits the output current to approximately
32mA to protect the transmitter and loop power/measurement circuitry.
It is possible to extend the output current range of the
XTR115/6 by connecting an external resistor from pin 3 to
pin 5, to change the current limit value. Since all output
current must flow through internal resistors, it is possible to
damage with excessive current. Output currents greater than
45mA may cause permanent damage.
OFFSETTING THE INPUT
A low scale of 4mA is produced by creating a 40µA input
current. This can be created with the proper value resistor
from VREF (Figure 2), or by generating offset in the input
drive circuitry.
VREG
XTR115
XTR116
VREF
VO
D/A
XTR115
RIN
VREG
VREG
VREF
Voltage
Reference
40µA
XTR115
XTR116
VREF
R0
62.5kΩ
Digital
Control
IIN
IO
D/A
≈
2.5V
Optical
Isolation
IIN
IRET
A1
0 to 160µA
IRET
Digital
Control
R1
2.475kΩ
≈
5V
µC
PWM
Out
VREG
Filter
RIN
Optical
Isolation
IRET
FIGURE 2. Creating Low-Scale Offset.
FIGURE 3. Digital Control Methods.
®
XTR115, XTR116
6
XTR115
XTR116
REVERSE-VOLTAGE PROTECTION
Most surge protection zener diodes have a diode characteristic in the forward direction that will conduct excessive
current, possibly damaging receiving-side circuitry if the
loop connections are reversed. If a surge protection diode is
used, a series diode or diode bridge should be used for
protection against reversed connections.
The XTR115/6 low compliance voltage rating (7.5V) permits the use of various voltage protection methods without
compromising operating range. Figure 4 shows a diode
bridge circuit which allows normal operation even when the
voltage connection lines are reversed. The bridge causes a
two diode drop (approximately 1.4V) loss in loop supply
voltage. This results in a compliance voltage of approximately 9V—satisfactory for most applications. A diode can
be inserted in series with the loop supply voltage and the V+
pin to protect against reverse output connection lines with
only a 0.7V loss in loop supply voltage.
RADIO FREQUENCY INTERFERENCE
The long wire lengths of current loops invite radio frequency
interference. RF can be rectified by the input circuitry of the
XTR115/6 or preceding circuitry. This generally appears as
an unstable output current that varies with the position of
loop supply or input wiring.
OVER-VOLTAGE SURGE PROTECTION
Interference may also enter at the input terminals. For
integrated transmitter assemblies with short connection to
the sensor, the interference more likely comes from the
current loop connections.
Remote connections to current transmitters can sometimes be
subjected to voltage surges. It is prudent to limit the maximum
surge voltage applied to the XTR115/6 to as low as practical.
Various zener diode and surge clamping diodes are specially
designed for this purpose. Select a clamp diode with as low a
voltage rating as possible for best protection. For example, a
36V protection diode will assure proper transmitter operation
at normal loop voltages, yet will provide an appropriate level
of protection against voltage surges. Characterization tests on
several production lots showed no damage with loop supply
voltages up to 65V.
8
V+
VREG
1
RIN
2
VREF
IIN
VIN
XTR115
XTR116
B
E
3
Maximum VPS must be
less than minimum
voltage rating of zener
diode.
7
IRET
IO
6
Q1
0.01µF
D1(1)
1N4148
Diodes
RL
5
VPS
The diode bridge causes
a 1.4V loss in loop supply
voltage.
4
NOTE: (1) Zener Diode 36V: 1N4753A or Motorola
P6KE39A. Use lower voltage zener diodes with loop
power supply voltages less than 30V for increased
protection. See “Over-Voltage Surge Protection.”
FIGURE 4. Reverse Voltage Operation and Over-Voltage Surge Protection.
®
7
XTR115, XTR116
IMPORTANT NOTICE
Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue
any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those
pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
Customers are responsible for their applications using TI components.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
intellectual property right of TI covering or relating to any combination, machine, or process in which such
semiconductor products or services might be or are used. TI’s publication of information regarding any third
party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.
Copyright  2000, Texas Instruments Incorporated