Amplificador de Aislamiento Inductivo Burr-Brown ISO213 Burr

7/22/2019 Amplificador de Aislamiento Inductivo Burr-Brown ISO213 Burr

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ISO213

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PDS-881E

Two-Port Isolated, Low Profile

ISOLATED INSTRUMENTATION AMPLIFIER

FEATURES GAIN RANGE: 0.5 - 5000

±10V INPUT SIGNAL RANGE

INSTRUMENTATION AMPLIFIER INPUTS

±40V INPUT OVER VOLTAGEPROTECTION

12-BIT ACCURACY

LOW PROFILE (Less Than 0.5" High)

SMALL FOOTPRINT

EXTERNAL POWER CAPABILITY(±14V at 3mA)

SYNCHRONIZATION CAPABILITY

SINGLE 12V TO 15V SUPPLY OPERATION

LOW POWER (45mW)

APPLICATIONS INDUSTRIAL PROCESS CONTROL:

Transducer Channel Isolator for

Thermocouples, RTDs, PressureBridges, Flow Meters

4mA TO 20mA LOOP ISOLATION

MOTOR AND SCR CONTROL

GROUND LOOP ELIMINATION

ANALYTICAL MEASUREMENTS

POWER PLANT MONITORING

DATA ACQUISITION/TEST EQUIPMENTISOLATION

MULTIPLEXED SYSTEMS WITHCHANNEL TO CHANNEL ISOLATION

ISO2

13

DESCRIPTIONISO213 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.

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 conditioningneeds can be met.

Gain

Set

8

7

–VIN

3

+VIN

1

FB

4

6

Com 12

5

38

37ACom 2

Isolation Barrier

+VSS Out

Com 2

+V

VOUT

CC

Clock Out

Clock In

DC/DCConverter

–VSS Out

31

32

34

35

®

©1995 Burr-Brown Corporation PDS-1281A Printed in U.S.A. April, 1995



2

®

ISO213

PARAMETER CONDITIONS MIN TYP MAX UNITS

ISOLATION

Voltage

Rated Continuous

AC, 50/60Hz 1500 Vrms

DC 2120 VDC

Rated 1 minAC, 50/60Hz 2500 Vrms

100% Test (AC, 50Hz) Partial Discharge 2500 Vrms

1s <5pC

Isolation-Mode Rejection(1) VISO = Rated

Continuous 50/60Hz

AC 115 dB

DC 160 dB

Barrier Resistance 1010 ΩBarrier Capacitance 15 pF

Leakage Current(2) VISO = 240Vrms, 60Hz 3 µArms

VISO = 240Vrms, 50Hz 2.4 µArms

GAIN

Equation

Initial Error G = 0.5 ±0.2 ±3 % FSR(8)

Gain vs Temperature G = 0.5 10 50 ppm of FSR/ °CNon-Linearity(3) VO = –5V to +5V, G = 0.5 0.01 0.025 %FSR

INPUT OFFSET VOLTAGEOffset Voltage RTI ±0.5 ±25/G mV

vs Temperature ±5 ±35/G µV/ °C vs Power Supply(4) G = 0.5,VCC = 14V to 16V ±3 mV/V

INPUT CURRENT

Bias ±1 ±10 nA

Offset ±1 ±10 nA

INPUT

Linear Input Range(5) G = 0.5 ±10 ±12 V

Common-Mode Rejection VCM = ±10V, ∆RS = 1kΩG = 0.5 73 90 dB

G = 5 89 110 dB

G = 50 98 120 dB

G = 500 100 125 dB

Impedance

Differential 1010 || 3 Ω || pF

Common-Mode 1010 || 6 Ω || pF

OUTPUT

Output Impedance 3 kΩVoltage Load = 1MΩ ±5 V

Ripple Voltage(6) f = clk 1 mVp-p

Output Noise f = 0 to 5kHz 20 µV/ √Hz

FREQUENCY RESPONSE

Small Signal Bandwidth VIN = 1Vp-p, –3dB, 1 kHz

G = 0.5

Full Signal Bandwidth VIN = 10Vp-p, –3dB, 200 Hz

G = 0.5

ISOLATED POWER OUTPUTS

Voltage Outputs (±VSS)(7) 3mA ±13 ±14 VDC

vs Temperature 7 mV/ °Cvs Load 180 mV/mA

Current Output(7)

(Both Loaded) VSS = ±13V 3 6 mA

(One Loaded) VSS = ±13V 4 6 mA

POWER SUPPLIES

Rated Voltage Rated Performance 15 VVoltage Range(5, 9) 11.4 to 16 V

Quiescent Current No Load 3 6 mA

TEMPERATURE RANGE

Specification 0 +70 °COperating –25 +85 °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.”

SPECIFICATIONSAt TA = +25°C, VCC = +15V, unless otherwise noted.

ISO213P

G = (1 + 50k/RG)/2



3

®

ISO213

ABSOLUTE MAXIMUM RATINGS

Supply Voltage Without Damage ......................................................... 18V

Continuous Isolation Voltage Across Barrier:............................ 2500Vrms

Storage Temperature Range............................................ –25°C to 100°CLead Temperature (soldering, 10s) ............................................... +300°CAmplifier Output Short-Circuit Duration ............... Continuous to Common

Output Voltage to Com 2 ............................................................... ±VCC /2

MODEL PACKAGE RANGE RATING 1 MIN

ISO213P 38-Pin Plastic ZIP –25°C to +85°C 2500Vrms

Bottom View

Com 1 2

FB 4

+VSS 6

GSA 8

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.

1 +VIN

3 –VIN

5 –VSS

7 GSB

31 +VCC

35 Clock In

37 ACom 2

PIN CONFIGURATION

PACKAGE INFORMATION

PACKAGE DRAWING

MODEL PACKAGE NUMBER(1)

ISO213P 38-Pin Plastic ZIP 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 ISOLATION

ELECTROSTATICDISCHARGE 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.

Com 2 32

Clock Out 34

VOUT 38



4

®

ISO213

IMR vs FREQUENCY

1k 10k 100k 1M 10M

85

80

75

70

65

60

55

50

45

40

Frequency (Hz)

I M

R ( d B )

100M

MAX VOUT AND VIN vs SUPPLY VOLTAGE

2

15

10

5

0

–5

–10

–15

Supply Voltage

M a x i m u

m

I n p u t V o l t a g e

0

–5

5

10

–10

M a x i m u m

O u t p u t V o l t a g e

4 6 8 10 12 14

–VOUT

+VOUT

+VIN

–VIN

±VOUT

+

–

STEP RESPONSE (f = 200Hz)

O u

t p u

t V o

l t a g e

( V )

+5

0

–5

0 5 10

Time (ms)

V = ±10V, G = 0.5IN

STEP RESPONSE (f = 2kHz)

0 500 1000

Time (µs)

O u t p u t V o l t a g e ( m V )

+500

0

–500

V = ±1V, G = 0.5IN

SINE RESPONSE (f = 200Hz)

0

+5

Time (ms)

O u t p u t V o l t a g e ( V )

0

–5

5 10

VIN = ±10V, G = 0.5

SINE RESPONSE (f = 2kHz)

O u t p u t V o l t a g e ( m V )+500

0

–500

0 500 1000

Time (µs)

V = ±1V, G = 0.5IN

TYPICAL PERFORMANCE CURVESAt TA = +25°C, VCC = +15V, unless otherwise noted.



5

®

ISO213

INPUT COMMON-MODE RANGE

vs OUTPUT VOLTAGE

Output Voltage (V)

C o m m o n - M o

d e

V o

l t a g e

( V )

–7.5 –5 0 2.5 7.5 –2.5

15

10

5

0

–5

–10

–15

5

All

Gains

All

Gains

G = 0.5 G = 0.5

G ≥ 5 G ≥ 5

VD/2

–

+ –

+

VCM

VOUT

VD/2

ISO213P

INPUT BIAS CURRENTvs INPUT OVERLOAD VOLTAGE

10

8

6

4

2

0

–2

–4

–6

–8

–10

I n p u t B i a s C u r r e n t ( m A )

Overload Voltage (V)

–40 0 40

G = 0.5

G = 500

G = 0.5

G = 500

0.4

0.3

0.2

0.1

0

30 40 60 80 100

GAIN ERROR vs CLOCK RATE

Clock (kHz)

G a

i n E r r o r

( % )

NON-LINEARITY vs CLOCK RATE

20 40 60 80 100

Clock (kHz)

30

20

10

0

N o n - L i n e a r i t y ( m % )

TYPICAL PERFORMANCE CURVES (CONT)

At TA = +25°C, VCC = +15V, unless otherwise noted.



6

®

ISO213

DISCUSSIONOF SPECIFICATIONSISO213 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 thatmonitor slowly varying processes. To power external func-

tions or networks, 3mA at ±14V typical is available at the

isolated port.

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 inputand +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.

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-

ficient for most applications at low frequencies with no

external networks connected.

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.

THEORY OF OPERATIONISO213 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.

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.

FIGURE 1. Power Supply and Signal Connections Shown for Non-Inverting, Unity Gain Configuration.

0.1µFRG

Gain

Set

8756

NOTE: (1) 10µF decoupling to be used with external loads connected

–VSS+VSS

3

2

–VIN

Com 1

1

VIN

VOUT

38

37

32

VOUT

ACom 2

Com 2

3435

Clock

Out

Clock

In

31

+VCC

+

+

(1)(1)

+VIN FB

4

Input Ground Plane

Output Ground Plane+15V

Isolation

Barrier∆VIN

∆FB

50kΩ

RG

= 1 +

10µF 10µF 10µF Tantalum

100µH

+

∆VIN

∆VOUT= /2

50kΩ

RG1 +



7

®

ISO213

ABOUT THE BARRIER

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 thecenter 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.

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-

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 aspartial 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.

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

FIGURE 2. Simplified Diagram of Isolation Amplifier.

–

+

4FB

7GSB

3 –VIN

1+VIN

8GSA

6+VSS

5 –VSS

2Com 1

0.47µF

+14V

–14V

0.47µF

Rectifier

Modulator

Signal

Power

25kHz

Oscillator

Demodulator

50kHz

38VOUT

37 ACom 2

31+VCC

34Clock Out

35

Clock In32

Com 2



8

®

ISO213

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.

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 mustdisplay <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.

INSTALLATION ANDOPERATING INSTRUCTIONSPOWER SUPPLY AND SIGNAL CONNECTIONS

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.

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

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 theequivalent 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.

ISOLATED POWER OUTPUT DRIVE CAPABILITY

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 fromthe 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.

FIGURE 3. Technique for Connecting Com 1 and Com 2.

VISO

CC+VCC –V

Power

Supply

Load

CircuitR

ACom 2

Com 2

Com 1Input

Common

CINT

CEXT 2

CEXT 1

VOUT

C and R have a direct effect.EXT 2

C has minimal effect on total IMR.EXT 1

FB

–

+



9

®

ISO213

number of ISO213s. See Figure 6, 7, and 8 for connections

in multiple ISO213 installations.

FIGURE 5. Equivalent Circuit, Clock Input/Output. Inverters

are CMOS.

0V +15V Sync

+V

Clk Out

Clk In

Com 2

CC

ISO213P/Slave

+V

Clk Out

Clk In

Com 2

CC

ISO213P/Slave

+V

Clk Out

Clk In

Com 2

CC

ISO213P/Master

FIGURE 7. Isolating the Clk Out Node.

FIGURE 6. Oscillator Connections for Synchronous Opera-

tion in Multiple ISO213P Installations.

NOISE

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-passfilter (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 1MΩwill 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.

SYNCHRONIZATIONOF THE INTERNAL OSCILLATOR

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.

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 severalISO213s 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

FIGURE 4. Recommended Decoupling and Power Distribu-

tion.

Clamp

Diodes

Clock

In

+VCC

Com 2

220pF39kΩ

Clock

Out

Power In Track Resistance/Inductance

I S O 2 1 3 P

Ground Plane

100µF 10µF

0.1µF 0.1µF 0.1µF 0.1µF

10µF 10µF

I S O 2 1 3 P

I S O 2 1 3 P

Clk Out Clk In Clk In Clk In Clk In

S l a v e

RS

22kΩ 22kΩ 22kΩ 22kΩ 22kΩ

S l a v e

S l a v e

S l a v e

S l a v e

M

a s t e r

Clk Out Clk In Clk In Clk In Clk In

S l a v e N

S l a v e 4

S l a v e 3

S l a v e 2

S l a v e 1

M a s t e r



10

®

ISO213

CHARGE ISOLATION

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.

A 22k Ω resistor (recommended maximum) together with the

39k Ω 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 22k Ω 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.

APPLICATIONSISO213 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.

ISO213 operates from a single +15V supply and offers low

power consumption and 12-bit accuracy. On the input side,

two isolated power supplies capable of supplying 3mA at

±14V typical are available to power external circuitry.

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 1.5k Ω resistor to set the output to

–5V at 4mA input.

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.

Clk In Clk In Clk In Clk In

D e v N

D e v 3

D e v 2

D e v 1

FIGURE 8. Recommended Synchronizing Scheme.

FIGURE 9. Isolated 4-20mA Current Receiver with Output Filter.

5 0.1µF

0.1µF

22kΩ 22kΩ

4-20mA

RG

1.02kΩ

50kΩ

RG

G = 1 + /2

25Ω

–VSS

+

–

31

32

38

37

100kΩ 100kΩ

(5%) (5%)

6.8nF

(10%)

6.8nF (10%)

+15V

6

–15V

4mA to 20mA

–10V to +10V

+15V

8

7

1

3

4mA to 20mA

–5V to +5V

+

OPA27

REF200

200µA

2

10µF

3

2

NOTE: All resistors are 0.1%

unless otherwise stated.

–

1.5kΩ



11

®

ISO213

NOTE: (1) e.g., strain gauge, pressure trans-

ducer, RTD, gas detection and analysis.

FIGURE 10. Instrument Bridge Isolation Amplifier.

FIGURE 11. ECG Amplifier With Right-Leg Drive.

FIGURE 12. Thermocouple Amplifier With Cold Junction Compensation and Down-Scale Burn-Out.

SEEBECK

ISA COEFFICIENT

TYPE MATERIAL (µV/°C) R1, R2

E + Chromel 58.5 66.5kΩ – Constantan

J + Iron 50.2 76.8kΩ – Constantan

K + Chromel 39.4 97.6kΩ – Alumel

T + Copper 38.0 102kΩ – Constantan

10µF

+VSS –VSS

2

6

5

+

VOUT

37

38

31

0.1µF

+15VRG

3 –

REF03

1kΩ

OPA1013 –2.5V

+2.5V

+VSS

–VSS

+VSS

32

10µF

1

1kΩ

1kΩ(1)

1kΩISO213P

7

8

RG /2VOUTLA

RL

RA

10kΩ

G = 52.8kΩ

2.8kΩ

1/2

OPA1013

390kΩ

390kΩ

1/2

OPA1013

ISO213P

REF102

R2R1

R3

Pt100

Cu

Cu

+VSS

K

610.0V

4

2

ISO213P VOUT

1MΩ

100Ω = RTD at 0°C

RG



12

®

ISO213

FIGURE 13. Isolated Current Monitoring Applications.

FIGURE 14. Isolated Temperature Sensing and Amplification.

200kΩ+

38

37

31

0.1µF

+15V

–

32

120Vrms

100A

4.7V

4.7V

200kΩ

0.1µF

3-Phase Y-Connected

Power Transformer

+

–

1kΩ

+500VDC

100kΩ 100kΩ

6.8nF

+15V

–15V

6.8nF

22kΩ22kΩ

3

2

6

OPA27

–10V

to

+10V

ISO213P

DC

Motor

V = 50mV (FS)D

VD

1

3

2

3

1

2

or

7

82

+

37

38

31

+15V

+VSS

10µF

1

–

32

3

ISO213P

REF200

2

100µA

1

100µA

8 7

6

100Ω at 0°C

0.385Ω /°C100Ω

3 Wire

PT100

–200°C to 850°C

50kΩ

RG

G = 1 + /2

RG

6

VOUT

0V at 0°C



13

®

ISO213

F I G U R E 1 5 .

C o m p l e t e T e m p

e r a t u r e A c q u i s i t i o n S y s t e m .

7 8 1 3

6 2

O P A 1 0 1 3

I S O 2 1 3

2 3

7 4

+

R 8

4 7 k Ω

R 2

1 M Ω

R 1 1

2 . 2

6 k Ω

R

E F

1 0 0

4 2 . 5

C 1

1 0 µ F

R 9

4 7 k Ω

C 2

1 n F

R 6

8 0 . 6 Ω

R 1 0

4 7 Ω

C W

1 0 n F

R 4

1 0 0 Ω

R 3

4 . 8

7 k Ω

I S O

T h e r m a l

B l o c k

T 1

A D S 7 8 0 6

O u t

R 1 3

1 3 k Ω

R 1 4

8 8 . 7

k Ω

3 1

3 2

3 7

3 8

7 8 0 5

G N D

2

I n

O

u t

1 µ F

+

2 . 2 µ F

+

1 0 µ F

V S

+ 1 2 V

6

1

1 9

R 1 7

1 0 0 Ω

R 1 8

1 k Ω

C W

U 3

2 8 2

3

1

1 0 0 µ H

R 1 6

9 . 5

3 k Ω

R 1 5

1 0 k Ω

2 . 2 n F

R 7

1 6 9 Ω

R 1

1 . 8

2 k Ω

R 5

8 . 2

5 k Ω

T y p e K

Amplificador de Aislamiento Inductivo Burr-Brown ISO213 Burr

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