ISO213P [BB]
Two-Port Isolated, Low Profile ISOLATED INSTRUMENTATION AMPLIFIER; 双端口隔离，薄型隔离仪表放大器
| 型号： | ISO213P |
| 厂家： | 
BURR-BROWN CORPORATION |
| 描述： | Two-Port Isolated, Low Profile ISOLATED INSTRUMENTATION AMPLIFIER |
| 文件： | 总13页 (文件大小：133K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
®
ISO213
ISO213
Two-Port Isolated, Low Profile
ISOLATED INSTRUMENTATION AMPLIFIER
FEATURES
APPLICATIONS
● GAIN RANGE: 0.5 - 5000
● INDUSTRIAL PROCESS CONTROL:
Transducer Channel Isolator for
Thermocouples, RTDs, Pressure
Bridges, Flow Meters
● ±10V INPUT SIGNAL RANGE
● INSTRUMENTATION AMPLIFIER INPUTS
● ±40V INPUT OVER VOLTAGE
● 4mA TO 20mA LOOP ISOLATION
● MOTOR AND SCR CONTROL
● GROUND LOOP ELIMINATION
● ANALYTICAL MEASUREMENTS
● POWER PLANT MONITORING
PROTECTION
● 12-BIT ACCURACY
● LOW PROFILE (Less Than 0.5" High)
● SMALL FOOTPRINT
● EXTERNAL POWER CAPABILITY
(±14V at 3mA)
● DATA ACQUISITION/TEST EQUIPMENT
ISOLATION
● SYNCHRONIZATION CAPABILITY
● SINGLE 12V TO 15V SUPPLY OPERATION
● LOW POWER (45mW)
● MULTIPLEXED SYSTEMS WITH
CHANNEL TO CHANNEL ISOLATION
Isolation Barrier
8
DESCRIPTION
Gain
Set
7
3
ISO213 signal isolation amplifier is a member of a
series of low-cost isolation products from Burr-Brown.
The low-profile ZIP plastic package allows PCB spac-
ings of 0.5" to be achieved, and the small footprint
results in efficient use of board space.
–VIN
38
37
VOUT
To provide isolation, the design uses high-efficiency,
miniature toroidal transformers in both the signal and
power paths. An uncommitted instrumentation ampli-
fier on the input and an isolated external bipolar supply
ensure the majority of input interfacing or conditioning
needs can be met.
1
+VIN
ACom 2
4
6
2
5
FB
+VSS Out
Com 1
DC/DC
Converter
31
32
+VCC
Com 2
–VSS Out
34
35
Clock Out
Clock In
International Airport Industrial Park
•
Mailing Address: PO Box 11400
Cable: BBRCORP
•
Tucson, AZ 85734
•
Street Address: 6730 S. Tucson Blvd.
•
Tucson, AZ 85706
Tel: (520) 746-1111 Twx: 910-952-1111
•
•
•
Telex: 066-6491
•
FAX: (520) 889-1510
•
Immediate Product Info: (800) 548-6132
©1995 Burr-Brown Corporation
PDS-1281A
Printed in U.S.A. April, 1995
SPECIFICATIONS
At TA = +25°C, VCC = +15V, unless otherwise noted.
ISO213P
TYP
PARAMETER
CONDITIONS
MIN
MAX
UNITS
ISOLATION
Voltage
Rated Continuous
AC, 50/60Hz
DC
1500
2120
Vrms
VDC
Rated 1 min
AC, 50/60Hz
100% Test (AC, 50Hz)
2500
2500
Vrms
Vrms
Partial Discharge
1s <5pC
VISO = Rated
Isolation-Mode Rejection(1)
Continuous 50/60Hz
AC
DC
115
160
1010
15
dB
dB
Ω
pF
µArms
µArms
Barrier Resistance
Barrier Capacitance
Leakage Current(2)
VISO = 240Vrms, 60Hz
3
2.4
V
ISO = 240Vrms, 50Hz
GAIN
Equation
Initial Error
Gain vs Temperature
Non-Linearity(3)
G = (1 + 50k/RG)/2
G = 0.5
G = 0.5
VO = –5V to +5V, G = 0.5
±0.2
10
0.01
±3
50
0.025
% FSR(8)
ppm of FSR/°C
%FSR
INPUT OFFSET VOLTAGE
Offset Voltage RTI
vs Temperature
±0.5 ±25/G
mV
µV/°C
mV/V
±5 ±35/G
±3
vs Power Supply(4)
G = 0.5,VCC = 14V to 16V
INPUT CURRENT
Bias
Offset
±1
±1
±10
±10
nA
nA
INPUT
Linear Input Range(5)
Common-Mode Rejection
G = 0.5
CM = ±10V, ∆RS = 1kΩ
±10
±12
V
V
G = 0.5
G = 5
G = 50
G = 500
73
89
98
90
dB
dB
dB
dB
110
120
125
100
Impedance
Differential
Common-Mode
1010 || 3
1010 || 6
Ω || pF
Ω || pF
OUTPUT
Output Impedance
Voltage
Ripple Voltage(6)
Output Noise
3
kΩ
V
mVp-p
µV/√Hz
Load = 1MΩ
f = clk
f = 0 to 5kHz
±5
1
20
FREQUENCY RESPONSE
Small Signal Bandwidth
VIN = 1Vp-p, –3dB,
G = 0.5
VIN = 10Vp-p, –3dB,
G = 0.5
1
kHz
Hz
Full Signal Bandwidth
200
ISOLATED POWER OUTPUTS
(7)
Voltage Outputs (±VSS
vs Temperature
vs Load
)
3mA
±13
±14
7
180
VDC
mV/°C
mV/mA
Current Output(7)
(Both Loaded)
(One Loaded)
VSS = ±13V
3
4
6
6
mA
mA
V
SS = ±13V
POWER SUPPLIES
Rated Voltage
Voltage Range(5, 9)
Quiescent Current
Rated Performance
No Load
15
11.4 to 16
3
V
V
mA
6
TEMPERATURE RANGE
Specification
Operating
0
–25
+70
+85
°C
°C
NOTES: (1) Isolation-mode rejection is the ratio of the change in output voltage to a change in isolation barrier voltage. (2) Tested at 2500Vrms 50Hz limit 25µA (barrier
is essentially capacitive). (3) Nonlinearity is the peak deviation of the output voltage from the best-fit straight line. It is expressed as the ratio of deviation to FSR.
(4) Power Supply Rejection is the change in VOS/Supply Change. (5) See max VOUT and VIN vs Supply Voltage in typical performance curves. (6) Ripple is the residual
component of the barrier carrier frequency generated internally. (7) Derated at VCC < 15V. (8) FSR = Full Scale Output Range = 10V. (9) Minimum supply voltage
is given as 11.4V. This is the minimum supply to ensure a ±5V output swing can be achieved. The ISO213 actually works down to a minimum supply of 4V as shown
in the typical performance curve “Max VOUT and VIN vs Supply Voltage.”
®
2
ISO213
PIN CONFIGURATION
ABSOLUTE MAXIMUM RATINGS
Bottom View
Supply Voltage Without Damage ......................................................... 18V
Continuous Isolation Voltage Across Barrier:............................ 2500Vrms
Storage Temperature Range ............................................ –25°C to 100°C
Lead Temperature (soldering, 10s) ............................................... +300°C
Amplifier Output Short-Circuit Duration ............... Continuous to Common
Output Voltage to Com 2 ............................................................... ±VCC /2
1
3
5
7
+VIN
–VIN
–VSS
GSB
Com 1 2
FB
+VSS
GSA
4
6
8
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.
31 +VCC
Com 2 32
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.
Clock Out 34
35 Clock In
37 ACom 2
VOUT 38
PACKAGE INFORMATION
PACKAGE DRAWING
MODEL
PACKAGE
38-Pin Plastic ZIP
NUMBER(1)
ISO213P
326
NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix D of Burr-Brown IC Data Book.
ORDERING INFORMATION
OPERATING
TEMPERATURE
RANGE
ISOLATION
RATING 1 MIN
MODEL
PACKAGE
ISO213P
38-Pin Plastic ZIP
–25°C to +85°C
2500Vrms
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.
®
ISO213
3
TYPICAL PERFORMANCE CURVES
At TA = +25°C, VCC = +15V, unless otherwise noted.
SINE RESPONSE (f = 2kHz)
SINE RESPONSE (f = 200Hz)
+500
+5
0
0
–500
–5
VIN = ±10V, G = 0.5
VIN = ±1V, G = 0.5
0
5
10
0
500
1000
Time (µs)
Time (ms)
STEP RESPONSE (f = 2kHz)
STEP RESPONSE (f = 200Hz)
+500
0
+5
0
–500
–5
VIN = ±10V, G = 0.5
VIN = ±1V, G = 0.5
0
500
1000
0
5
10
Time (µs)
Time (ms)
MAX VOUT AND VIN vs SUPPLY VOLTAGE
IMR vs FREQUENCY
10
15
85
80
75
70
65
60
55
50
45
40
10
5
+VOUT
5
+VIN
–VIN
+
0
0
–5
–10
–15
–5
–10
±VOUT
–
–VOUT
2
4
6
8
10
12
14
1k
10k
100k
1M
10M
100M
Supply Voltage
Frequency (Hz)
®
4
ISO213
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C, VCC = +15V, unless otherwise noted.
NON-LINEARITY vs CLOCK RATE
GAIN ERROR vs CLOCK RATE
30
20
10
0
0.4
0.3
0.2
0.1
0
20
40
60
80
100
30
40
60
80
100
Clock (kHz)
Clock (kHz)
INPUT COMMON-MODE RANGE
vs OUTPUT VOLTAGE
INPUT BIAS CURRENT
vs INPUT OVERLOAD VOLTAGE
15
10
8
G ≥ 5
G ≥ 5
10
5
6
G = 0.5
G = 0.5
G = 500
G = 500
4
2
–
VOUT
VD/2
0
0
+
–
ISO213P
G = 0.5
G = 0.5
VD/2
–2
–4
–6
–8
–10
+
–5
–10
–15
VCM
All
Gains
All
Gains
–7.5
–5
–2.5
0
2.5
5
7.5
–40
0
40
Output Voltage (V)
Overload Voltage (V)
®
ISO213
5
ficient for most applications at low frequencies with no
external networks connected.
DISCUSSION
OF SPECIFICATIONS
The ripple on ±VSS will typically be 100mVp-p at 25kHz.
Loading the supplies will increase the ripple unless extra
filtering is added externally; a capacitor of 1µF is normally
sufficient for most applications, although in some cases
10µF may be required. Noise introduced onto ±VSS should
be decoupled to prevent degraded performance.
ISO213 is intended for applications where isolation and
input signal conditioning are required. The best signal-to-
noise performance is obtained when the input amplifier gain
setting is such that FB pin has a full scale range of ±10V. The
bandwidth is internally limited to typically 1kHz, making
the device ideal for use in conjunction with sensors that
monitor slowly varying processes. To power external func-
tions or networks, 3mA at ±14V typical is available at the
isolated port.
THEORY OF OPERATION
ISO213 has no galvanic connection between the input and
output. The analog input signal is multiplied by the gain of
the input amplifier and accurately reproduced at the output.
A simplified diagram of ISO213 is shown in Figure 2. The
design consists of a DC/DC converter, an uncommitted
input instrumentation amplifier, a modulator circuit and a
demodulator circuit with a gain of 0.5. Magnetic isolation is
provided by separate transformers in the power and signal
paths.
LINEARITY PERFORMANCE
ISO213 offers non-linearity performance compatible with
12-bit resolution systems (0.025%). Note that the specifica-
tion is based on a best-fit straight line.
INPUT PROTECTION
The inputs of ISO213 are individually protected for voltages
up to ±40V. For example, a condition of –40V on one input
and +40V on the other input will not cause damage. Internal
circuitry on each input provides low series impedance under
normal signal conditions. To provide equivalent protection,
series input resistors would contribute excessive noise. If the
input is overloaded, the protection circuitry limits the input
current to a safe value of approximately 1.5mA to 5mA. The
typical performance curve “Input Bias Current vs Input
Overload Voltage” shows this input current limit behavior.
The inputs are protected even if the power supplies are
disconnected or turned off.
The DC/DC converter provides power and synchronization
signals across the isolation barrier to operate the instrumen-
tation amplifier and modulator circuitry. It also has suffi-
cient capacity to power external input signal conditioning
networks. The uncommitted instrumentation amplifier may
be configured for signal buffering or amplification, depend-
ing on the application.
The modulator converts the input signal to an amplitude-
modulated AC signal that is magnetically coupled to the
demodulator by a miniature transformer providing the
signal-path isolation. The demodulator recovers the input
signal from the modulated signal using a synchronous tech-
nique to minimize noise and interference.
USING ±VSS TO POWER EXTERNAL CIRCUITRY
The DC/DC converter in ISO213 runs at a switching fre-
quency of 25kHz. Internal rectification and filtering is suf-
Isolation
Barrier
∆VIN
∆FB
50kΩ
RG
= 1 +
4
35
34
1
3
+VIN FB
Clock Clock
In
Out
VIN
∆VIN
∆VOUT
50kΩ
RG
38
–VIN
= 1 +
/2
VOUT
VOUT
2
37
32
Com 1
ACom 2
Com 2
Gain
Set
+VSS –VSS
+VCC
31
6
5
7
8
RG
0.1µF
(1)
(1)
+
10µF Tantalum
+
10µF
10µF
+
Input Ground Plane
Output Ground Plane
100µH
+15V
NOTE: (1) 10µF decoupling to be used with external loads connected
FIGURE 1. Power Supply and Signal Connections Shown for Non-Inverting, Unity Gain Configuration.
®
6
ISO213
ABOUT THE BARRIER
zation requires a higher applied voltage to start the discharge
and a lower voltage to extinguish it once started. The higher
start voltage is known as the inception voltage and the lower
voltage is called the extinction voltage. Just as the total
insulation system has an inception voltage, so do the individ-
ual voids. A voltage will build up across a void until its
inception voltage is reached. At this point, the void will
ionize, effectively shorting itself out. This action redistrib-
utes electrical charge within the dielectric and is known as
partial discharge. If the applied voltage gradient across the
device continues to rise, another partial discharge cycle
begins. The importance of this phenomenon is that if the
discharge does not occur, the insulation system retains its
integrity. If the discharge begins and is allowed to continue,
the action of the ions and electrons within the defect will
eventually degrade any organic insulation system in which
they occur. The measurement of partial discharge is both
useful in rating the devices and in providing quality control
of the manufacturing process. The inception voltage of these
voids tend to be constant, so that the measurement of total
charge being redistributed within the dielectric is a very
good indicator of the size of the voids and their likelihood of
becoming an incipient failure.
For any isolation product, barrier integrity is of paramount
importance in achieving high reliability. ISO213 uses min-
iature toroidal transformers designed to give maximum
isolation performance when encapsulated with a high dielec-
tric-strength material. The internal component layout is
designed so that circuitry associated with each side of the
barrier is positioned at opposite ends of the package. Areas
where high electric fields can exist are positioned in the
center of the package. The result is that the dielectric
strength of the barrier typically exceeds 3kVrms.
ISOLATION VOLTAGE RATINGS
Because a long term test is impractical in a manufacturing
situation, the generally accepted practice is to perform a
production test at a high voltage for some shorter time. The
relationship between actual test voltage and the continuous
derated maximum specification is an important one. Histori-
cally, Burr-Brown has chosen a deliberately conservative
one: VTEST = (2 x ACrms continuous rating) + 1000V for ten
seconds, followed by a test at rated ACrms voltage for one
minute.
Recent improvements in high voltage stress testing have
produced a more meaningful test for determining maximum
permissible voltage ratings, and Burr-Brown has chosen to
apply this new technology to the manufacture and testing of
ISO213.
The bulk inception voltage, on the other hand, varies with
the insulation system and the number of ionization defects.
This directly establishes the absolute maximum voltage
(transient) that can be applied across the test device before
destructive partial discharge can begin.
Measuring the bulk extinction voltage provides a lower,
more conservative, voltage from which to derive a safe
continuous rating. In production, it’s acceptable to measure
at a level somewhat below the expected inception voltage
and then de-rate by a factor related to expectations about the
PARTIAL DISCHARGE
When an insulation defect such as a void occurs within an
insulation system, the defect will display localized corona or
ionization during exposure to high voltage stress. This ioni-
4
FB
7
GSB
Signal
3
–VIN
+VIN
GSA
–
+
38
Modulator
VOUT
1
8
Demodulator
37
ACom 2
31
+VCC
+14V
50kHz
Power
34
35
32
6
5
2
+VSS
–VSS
Clock Out
Clock In
Com 2
Oscillator
25kHz
–14V
Rectifier
0.47µF
0.47µF
Com 1
FIGURE 2. Simplified Diagram of Isolation Amplifier.
®
ISO213
7
system transients. The isolation barrier has been extensively
evaluated under a combination of high temperatures and
high voltage to confirm its performance in this respect.
ISO213 is free from partial discharges at rated voltages.
CEXT 1 has minimal effect on total IMR.
CEXT 2 and R have a direct effect.
FB
–
PARTIAL DISCHARGE TESTING IN PRODUCTION
This test method provides far more qualitative information
about stress withstand levels than did previous stress tests. It
also provides quantitative measurements from which quality
assurance and control measures can be based. Tests similar
to this test have been used by some manufacturers such as
those of high voltage power distribution equipment for some
time. They employed a simple measurement of RF noise to
detect ionization. This method was not quantitative with
regard to energy of the discharge and was not sensitive
enough for small components such as isolation amplifiers.
Now, however, manufacturers of HV test equipment have
developed means to measure partial discharge, and VDE, the
German standards group, has adopted use of this method for
the testing of opto-couplers. To accommodate poorly de-
fined transients, the part under test is exposed to a voltage
that is 1.6 times the continuous rated voltage and must
display <5pC partial discharge level in a 100% production
test. Where transients are not present on an applied voltage
and the bulk inception voltage is not exceeded, degradation
will not take place. This is the case where OEM production
testing is performed to satisfy regulatory requirements. The
normal test is to apply a relatively slow ramp to a defined
test voltage. Maintain that voltage for 1 minute and then
ramp to zero. Where this test voltage is less than or equal to
the partial discharge test voltage it can be seen that degrada-
tion will not occur. Hence ISO213 is guaranteed to with-
stand a continuous test voltage for 1 minute at the partial
discharge test voltage.
VOUT
CINT
Load
Circuit
R
+
ACom 2
Com 2
CEXT 2
–VCC +VCC
CEXT 1
Power
Supply
Com 1
Input
Common
VISO
FIGURE 3. Technique for Connecting Com 1 and Com 2.
reference leads, must be minimized. Any capacitance across
the barrier will increase AC leakage and, in conjunction with
ground line resistance, may degrade high frequency IMR.
VOLTAGE GAIN MODIFICATIONS
The uncommitted instrumentation amplifier at the input can
be used to provide gain, signal inversion, or current to
voltage conversion. The standard design approach for any
instrumentation amplifier stage can be used, provided that
the full scale voltage appearing on FB does not exceed ±10V.
Also, it should be noted that the current required to drive the
equivalent impedance of any feedback network is supplied
by the internal DC/DC converter and must be taken into
account when calculating the loading added to ±VSS.
INSTALLATION AND
OPERATING INSTRUCTIONS
POWER SUPPLY AND SIGNAL CONNECTIONS
ISOLATED POWER OUTPUT DRIVE CAPABILITY
As with any mixed analog and digital signal component,
correct decoupling and signal routing precautions must be
used to optimize performance. Figure 1 shows the proper
power supply and signal connections. VCC should be by-
passed to Com 2 with a 0.1µF ceramic capacitor and 100µH
inductor as close to the device as possible. Short leads will
minimize lead inductance. A ground plane will also reduce
noise problems. If a low impedance ground plane is not
used, signal common lines, and ACom 2 should be tied
directly to the ground at the supply and Com 2 returned via
a separate trace to the supply ground.
On the input side of ISO213, there are two power supplies
capable of delivering 3mA at ±14V typical to power external
circuitry. When using these supplies with external loads, it
is recommended that additional decoupling in the form of
10µF tantalum bead capacitors, is added to improve the
voltage regulation. Loss of linearity will result if additional
filtering is not used with an output load. Again, power
dissipated in a feedback network must be subtracted from
the available power output at ±VSS.
If ISO213 is to be used in multiple applications, care should
be taken in the design of the power distribution network,
especially when all ISO213s are synchronized. It is best to
use a well decoupled distribution point and to take power
to each ISO213 from this point in a star arrangement as shown
in Figure 4.
To avoid gain and isolation mode (IMR) errors introduced
by the external circuit, connect grounds as indicated in
Figure 3. Layout practices associated with isolation amplifi-
ers are very important. In particular, the capacitance associ-
ated with the barrier, and series resistance in the signal and
®
8
ISO213
number of ISO213s. See Figure 6, 7, and 8 for connections
in multiple ISO213 installations.
Power In
Track Resistance/Inductance
+VCC
100µF
10µF
10µF
10µF
Clock
In
0.1µF
0.1µF
0.1µF
0.1µF
39kΩ
220pF
Ground Plane
Clamp
Diodes
Clock
Out
FIGURE 4. Recommended Decoupling and Power Distribu-
tion.
Com 2
NOISE
FIGURE 5. Equivalent Circuit, Clock Input/Output. Inverters
are CMOS.
Output noise is generated by residual components of the
25kHz carrier that have not been removed from the signal.
This noise may be reduced by adding an output low-pass
filter (see Figure 9). The filter time constant should be set
below the carrier frequency. The output from ISO213 is a
switched capacitor and requires a high impedance load to
prevent degradation of linearity. Loads of less than 1MΩ
will cause an increase in noise at the carrier frequency and
will appear as ripple in the output waveform. Since the
output signal power is generated from the input side of the
barrier, decoupling of the ±VSS outputs will improve the
signal to noise ratio.
ISO213P/Master
+VCC
Clk Out
Clk In
Com 2
ISO213P/Slave
+VCC
Clk Out
Clk In
Com 2
ISO213P/Slave
SYNCHRONIZATION
OF THE INTERNAL OSCILLATOR
+VCC
Clk Out
Clk In
Com 2
ISO213 has an internal oscillator and associated timing
components, which can be synchronized. This alleviates the
requirement for an external high-power clock driver. The
typical frequency of oscillation is 50kHz. The internal clock
will start when power is applied to ISO213 and Clk In is not
connected.
0V +15V Sync
FIGURE 6. Oscillator Connections for Synchronous Opera-
tion in Multiple ISO213P Installations.
Because the oscillator frequency of each ISO213 can be
marginally different, “beat” frequencies ranging from a few
Hz to a few kHz can exist in multiple amplifier applications.
The design of ISO213 accommodates “internal synchro-
nous” noise, but a synchronous beat frequency noise will not
be strongly attenuated, especially at very low frequencies if
it is introduced via the power, signal, or potential grounding
paths. To overcome this problem in systems where several
ISO213s are used, the design allows synchronization of each
oscillator in a system to one frequency. Do this by forcing
the timing node on the internal oscillator with an external
driver connected to Clk In (Figure 5). The driver may be an
external component with Series 4000 CMOS characteristics,
or one ISO213 in the system can be used as the master clock
for the system. An alternative where a specific frequency is
not required is to lock all ISO213s together by joining all
Clk Ins. This method can be used to lock an unlimited
22kΩ
22kΩ
22kΩ
22kΩ
22kΩ
Clk Out
Clk In
Clk In
Clk In
Clk In
RS
Clk Out
Clk In
Clk In
Clk In
Clk In
FIGURE 7. Isolating the Clk Out Node.
®
ISO213
9
CHARGE ISOLATION
two isolated power supplies capable of supplying 3mA at
±14V typical are available to power external circuitry.
When more than one ISO213 is used in synchronous mode,
the charge which is returned from the timing capacitor
(220pF in Figure 5) on each transition of the clock becomes
significant. Figure 7 illustrates a method of isolating the
“Clk Out” clamp diodes (Figure 5) from this charge.
APPLICATIONS FLEXIBILITY
In Figure 9, ISO213 +Vss isolated supply powers a REF200
to provide an accurate 200µA current source. This current is
used via the 1.5kΩ resistor to set the output to
–5V at 4mA input.
A 22kΩ resistor (recommended maximum) together with the
39kΩ internal oscillator timing resistor (Figure 5) forms a
potential divider. The ratio of these resistors should be
greater than 0.6 which ensures that the input voltage triggers
the inverter connected to “Clk In”. If using a single resistor,
then account must be taken of the paralleled timing resistors.
This means that the 22kΩ resistor must be halved to drive
two ISO213s, or divided by 8 if driving 8 ISO213s to insure
that the ratio of greater than 0.6 is maintained. The series
resistors shown in Figure 7 reduce the high frequency
content of the power supply current. Figure 8 can be used
where a specific frequency of operation is not required.
The primary function of the output circuitry is to add gain,
to produce a ±10V output and to reduce output impedance.
The addition of a few resistors and capacitors provides a low
pass filter with a cutoff frequency equal to the full signal
bandwidth of ISO213, typically 200Hz. The filter response
is flat to 1dB and rolls off from cut off at –12dB per octave.
The accuracy of REF200 and external resistors eliminates
the need for expensive trim pots and adjustments. The errors
introduced by the external circuitry only add about 10% of
ISO213 specified gain and offset voltage error.
APPLICATIONS
ISO213 isolation amplifier, together with a few low cost
components, can isolate and accurately convert a 4-to-20mA
input to a ±10V output with no external adjustment. Its low
height (0.43" (11mm) ) and small footprint (2.5" x 0.33"
(57mm x 8mm) ) make it the solution of choice in 0.5" board
spacing systems and in all applications where board area
savings are critical.
Clk In
Clk In
Clk In
Clk In
ISO213 operates from a single +15V supply and offers low
power consumption and 12-bit accuracy. On the input side,
FIGURE 8. Recommended Synchronizing Scheme.
–VSS
10µF
REF200
200µA
6.8nF (10%)
+15V
0.1µF
+15V
5
1
31
4mA to 20mA
–10V to +10V
100kΩ
100kΩ
38
3
2
4-20mA
+
25Ω
6
37
(5%)
(5%)
OPA27
–
1.5kΩ
3
32
6.8nF
(10%)
2
8
0.1µF
4mA to 20mA
–5V to +5V
–15V
7
NOTE: All resistors are 0.1%
unless otherwise stated.
RG
1.02kΩ
22kΩ
22kΩ
50kΩ
RG
G = 1 +
/2
FIGURE 9. Isolated 4-20mA Current Receiver with Output Filter.
®
10
ISO213
RG
+VSS
+15V
7
REF03
+2.5V
0.1µF
8
3
–
31
38
VOUT
ISO213P
1k
1k
1k
Ω
Ω
Ω
37
1
32
+
+VSS
5
1kΩ(1)
6
2
OPA1013
–2.5V
10µF
10µF
–VSS
NOTE:(1)e.g.,straingauge,pressuretrans-
ducer, RTD, gas detection and analysis.
+VSS –VSS
FIGURE 10. Instrument Bridge Isolation Amplifier.
2.8kΩ
VOUT
LA
RG/2
ISO213P
RA
2.8kΩ
G = 5
390kΩ
1/2
OPA1013
1/2
OPA1013
10kΩ
RL
390kΩ
FIGURE 11. ECG Amplifier With Right-Leg Drive.
10.0V
6
+VSS
REF102
2
R1
R2
4
1MΩ
Pt100
SEEBECK
ISA
TYPE
COEFFICIENT
Cu
Cu
MATERIAL
(µV/°C)
R1, R2
K
VOUT
E
+ Chromel
– Constantan
58.5
66.5kΩ
RG
ISO213P
J
+ Iron
– Constantan
50.2
39.4
38.0
76.8kΩ
97.6kΩ
102kΩ
R3
100Ω = RTD at 0°C
K
T
+ Chromel
– Alumel
+ Copper
– Constantan
FIGURE 12. Thermocouple Amplifier With Cold Junction Compensation and Down-Scale Burn-Out.
®
ISO213
11
+500VDC
ISO213P
Ω
1k
3
–
+
VD
+15V
1
VD = 50mV (FS)
6.8nF
0.1µF
2
DC
Motor
+15V
31
100kΩ 100kΩ
3
2
38
37
–10V
to
6
OPA27
6.8nF
+10V
32
or
–15V
22kΩ
22kΩ
120Vrms
100A
3
3-Phase Y-Connected
Power Transformer
–
+
200kΩ
1
2
4.7V
4.7V
0.1µF
200kΩ
FIGURE 13. Isolated Current Monitoring Applications.
+VSS
10µF
8
7
2
REF200
6
1
+15V
3 Wire
PT100
–200°C to 850°C
100µA 100µA
6
3
–
0V at 0°C
VOUT
31
100Ω at 0°C
0.385Ω/°C
38
ISO213P
100Ω
37
1
32
+
50kΩ
RG
G = 1 +
/2
2
8
7
RG
FIGURE 14. Isolated Temperature Sensing and Amplification.
®
12
ISO213
®
ISO213
13
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