Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsLinear ICsLinear IC - Op-amp Isolation amp CDIP 16

Precision Low Cost

ISOLATION AMPLIFIER

ISO120

ISO121

Signal

Com 2

–V

Gnd 2

Ext Osc

Gnd 1

–V

Signal

Com 1

OUT

Sense

Isolation Barrier

DESCRIPTION

The ISO120 and ISO121 are precision isolation ampli-

fiers incorporating a novel duty cycle modulation-

demodulation technique. The signal is transmitted

digitally across a 2pF differential capacitive barrier.

With digital modulation the barrier characteristics do

not affect signal integrity, which results in excellent

reliability and good high frequency transient immu-

nity across the barrier. Both the amplifier and barrier

capacitors are housed in a hermetic DIP. The ISO120

and ISO121 differ only in package size and isolation

voltage rating.

These amplifiers are easy to use. No external compo-

nents are required for 60kHz bandwidth. With the

addition of two external capacitors, precision specifi-

cations of 0.01% max nonlinearity and 150µV/°C max

drift are guaranteed with 6kHz bandwidth. A

power supply range of ±4.5V to ±18V and low quies-

cent current make these amplifiers ideal for a wide

range of applications.

FEATURES

● 100% TESTED FOR PARTIAL DISCHARGE

● ISO120: Rated 1500Vrms

● ISO121: Rated 3500Vrms

● HIGH IMR: 115dB at 60Hz

● USER CONTROL OF CARRIER

FREQUENCY

● LOW NONLINEARITY:

±0.01% max

● BIPOLAR OPERATION: V

= ±10V

● 0.3"-WIDE 24-PIN HERMETIC DIP, ISO120

● SYNCHRONIZATION CAPABILITY

● WIDE TEMP RANGE: –55

°C to +125°C

(ISO120)

APPLICATIONS

● INDUSTRIAL PROCESS CONTROL: Trans-

ducer Isolator for Thermocouples, RTDs,

Pressure Bridges, and Flow Meters, 4mA

to 20mA Loop Isolation

● GROUND LOOP ELIMINATION

● MOTOR AND SCR CONTROL

● POWER MONITORING

● ANALYTICAL MEASUREMENTS

● BIOMEDICAL MEASUREMENTS

● DATA ACQUISITION

● TEST EQUIPMENT

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SBOS158

Summary of content (16 pages)

PAGE 1
ISO120 ISO121 Precision Low Cost ISOLATION AMPLIFIER FEATURES APPLICATIONS ● ● ● ● ● ● INDUSTRIAL PROCESS CONTROL: Transducer Isolator for Thermocouples, RTDs, Pressure Bridges, and Flow Meters, 4mA to 20mA Loop Isolation ● GROUND LOOP ELIMINATION ● MOTOR AND SCR CONTROL ● POWER MONITORING ● ANALYTICAL MEASUREMENTS ● BIOMEDICAL MEASUREMENTS ● ● ● ● ● 100% TESTED FOR PARTIAL DISCHARGE ISO120: Rated 1500Vrms ISO121: Rated 3500Vrms HIGH IMR: 115dB at 60Hz USER CONTROL OF CARRIER FREQUENCY LOW NONLINEARIT
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SPECIFICATIONS ELECTRICAL At TA = +25°C: VS1 = VS2 = ±15V: and RL = 2kΩ, unless otherwise noted.
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ABSOLUTE MAXIMUM RATINGS CONNECTION DIAGRAM Supply Voltage (any supply) ............................................................... 18V VIN, Sense Voltage .......................................................................... ±100V External Oscillator Input .................................................................... ±25V Signal Common 1 to Ground 1 ........................................................... ±1V Signal Common 2 to Ground 2 ..................................................
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TYPICAL PERFORMANCE CURVES TA = +25°C; VS1 = VS2 = ±15V; and RL = 2kΩ, unless otherwise noted. ISOLATION MODE VOLTAGE vs FREQUENCY ISO120 ISOLATION MODE VOLTAGE vs FREQUENCY ISO121 Max DC Rating Max DC Rating Max AC Rating 1k 2.
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TYPICAL PERFORMANCE CURVES (CONT) TA = +25°C; VS1 = VS2 = ±15V; and RL = 2kΩ, unless otherwise noted.
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TYPICAL PERFORMANCE CURVES (CONT) TA = +25°C; VS1 = VS2 = ±15V; and RL = 2kΩ, unless otherwise noted. STEP RESPONSE +10 +10 0 0 Output Voltage (V) Output Voltage (V) STEP RESPONSE –10 +10 0 –10 +10 0 –10 –10 0 250 0 500 50 100 Time (µs) Time (µs) THEORY OF OPERATION SYNCHRONIZED MODE A unique feature of the ISO120 and ISO121 is the ability to synchronize the modulator to an external signal source.
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C1(1) C1H C2(1) Isolation Barrier C1L 200µA 200µA 1pF 1pF X X 1pF Sense 200kΩ 150pF 100µA VIN C2H C2L Sense 1pF 150pF 200kΩ Sense 100µA Signal Com 1 30kΩ Ext Osc A1 V OUT Signal Com 2 A2 16kΩ S/H G=1 16kΩ S/H G=6 50pF +V S1 Gnd 1 –V S1 +V S2 Gnd 2 –V S2 NOTE: (1) Optional. See text. FIGURE 1. Block Diagram. The value of the external modulator capacitor, C1, depends on the frequency of the external clock signal. Table I lists recommended values.
PAGE 8
connected directly to VOUT or may be connected to a remote load to eliminate errors due to IR drops. Pins are provided for use of external integrator capacitors. The C1H and C2H pins are connected to the integrator summing junctions and are therefore particularly sensitive to external pickup. This sensitivity will most often appear as degraded IMR or PSR performance. AC or DC currents coupled into these pins results in VERROR = IERROR X 200kΩ at the output.
PAGE 9
resolution with a typical trim potentiometer. The output will have some sensitivity to power supply variations. For a ±100mV trim, power supply sensitivity is 8mV/V at the output. VIN output are not significant under these circumstances unless the input signal contains significant components above 250kHz. There are two ways to use these characteristics.
PAGE 10
because IMV-induced errors behave like input-referred error signals. To predict the total IMR, divide the isolation voltage by the IMR shown in IMR vs Frequency performance curve and compute the amplifier response to this input-referred error signal from the data given in the Signal Response vs Carrier Frequency performance curve. Due to effects of very high-frequency signals, typical IMV performance can be achieved only when dV/dT of the isolation mode voltage falls below 1000V/µs.
PAGE 11
APPLICATIONS The ISO120 and ISO121 isolation amplifiers are used in three categories of applications: 2. Accurate isolation of signals from severe ground noise and, 3. Fault protection from high voltages in analog measurements. 1. Accurate isolation of signals from high voltage ground potentials, Figures 7 through 12 show a variety of Application Circuits. APPLICATION CIRCUITS 20µH + 'E +15V 0.3µF 10µF TO PWS740-2 4 6 8 +V IN 5 PWS740-1 3 0.3µF PWS740-3 2 0.3µF 0.
PAGE 12
3θ Y-Connected Power Transformer +VS1 –VS1 +VS2 –VS2 +VS1 120Vrms 100A 1 3 4 15 200kΩ 0.005 Power Resistor 2 8 C1 + 10 INA110 0.001µF 1 200kΩ – 9 7 6 –VSI 16 2 11 10 23 ISO 120 21 24 22 VOUT 13 14 C2 9 12 C1 = 1000pF C2 = 1000pF Differential input accurately senses power resistor voltage. Two resistors protect INA110 from open power resistor. High frequency spike reject filter has fCO = 400Hz. FIGURE 8. Isolated Powerline Monitor. 1mV 5MΩ 5.
PAGE 13
10kΩ 23 3 +V 5kΩ 15 V= e1 =12V 10kΩ 11 ISO 21 120 22 e2 =12V 10 2 9, 12 4 16 –V Multiplexer 24 e1 Charge/Discharge Control Control Section +V –V e49 =12V 23 21 e50 =12V 3 +V 7 11 ISO 120 10kΩ 4 5kΩ 15 25kΩ 10 25kΩ 5 2 9, 12 22 24 10kΩ 4 16 –V 25kΩ 6 INA105 3 1 V= e50 2 25kΩ FIGURE 10. Battery Monitor for a 600V Battery Power System. 3 1mA 1mA 10 8 5 RS 150Ω +VS = 15V on PWS740 XTR101 0.01µF 6 4 R1 100Ω 11 7 RTD (PT100) 7 RL 250Ω 3 250Ω R2 2.
PAGE 14
23 10 VOUT1 11 ISO 120 9 16 12 V– 15 V+ 1 4 VOUT2 22 Ext Osc 24 3 +VS1 0.3µF 4 ISO 120 9 1 2 12 V– 15 V+ 4 1 20kΩ Gnd2 0.3µF 4 8 5 6 3 3 1 2 3 6 5 4 4 VIN2 20pF 20kΩ PWS740-3 6 PWS740-2 6 21 22 Ext Osc 3 +VS2 24 –VS2 20pF PWS740-3 3 V+ VIN1 11 16 –VS1 Gnd1 21 23 10 PWS740-2 4 Up to 6 more channels PWS740-1 6 3 5 20µH 10µF 0.3µF 0.3µF FIGURE 12. Synchronized-Multichannel Isolation System.
PAGE 15
PACKAGE OPTION ADDENDUM www.ti.
PAGE 16
IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.