Texas Instruments ISO122PE4

Overview

ISO122PE4 from Texas Instruments is a precision analog isolation amplifier with galvanic isolation via integrated 2-pF differential capacitive barrier, 1500 V_rms rated isolation voltage, 140 dB IMR at 60 Hz, ±10 V bipolar output swing, and 50 kHz small-signal bandwidth - used in industrial transducer signal conditioning where ground loop elimination and high common-mode rejection are critical.

For engineers reviewing the ISO122PE4 datasheet, ISO122PE4 pinout, ISO122PE4 application, or ISO122PE4 equivalent, key selection considerations include its fixed unity-gain configuration, dual ±4.5 V to ±18 V supply operation, 0.020% maximum nonlinearity, and compatibility with thermocouple, RTD, and 4–20 mA loop isolation circuits.

Technical Context

The ISO122PE4 employs duty-cycle modulation-demodulation across an on-package capacitive barrier, eliminating dependence on barrier dielectric properties for signal fidelity. Its modulator integrates VIN/200 kΩ against a switched ±100 mA current source synchronized to a 500 kHz internal oscillator, generating a digital duty-cycle waveform.

The demodulator recovers the analog signal using a sense amplifier and integrator (A2) with 200 kΩ feedback, while sample-and-hold stages suppress 500 kHz carrier ripple. Input and output sections are laser-trimmed for matching, achieving 200 µV/°C VOS drift and 4 µV/√Hz input noise.

Key Specifications

Pinout & Package

ISO122PE4 is supplied in a 16-pin plastic DIP (PDIP) package with 17.90 mm × 7.50 mm body size and through-hole mounting. Pin 1 is +VS1; pin 2 is –VS1; pin 7 is VOUT; pin 8 is GND2 (low-side ground); pin 9 is +VS2; pin 10 is –VS2; pin 15 is VIN; pin 16 is GND1 (high-side ground).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar isolation amplifier applications.

Compared with ISO122PE4, ISO124P offers superior bandwidth and linearity at higher power and design complexity, while AMC1301DWVR shifts to digital output domain - making ISO122PE4 the optimal choice for analog-output, low-cost, fixed-gain isolation where 50 kHz bandwidth and proven reliability are sufficient.

Availability

ISO122PE4 is available at Aetrix Electronics and suitable for industrial process control, motor drive feedback, and 4–20 mA loop isolation requiring stable component supply across extended production lifecycles.

Supply support for ISO122PE4 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company specializing in analog and embedded processing technologies, with leadership in precision signal chain and isolation solutions.

The ISO122PE4 belongs to TI's precision isolation amplifier product line, designed specifically for analog signal transmission across high-voltage barriers in industrial automation, energy monitoring, and test equipment.

FAQ

What is the isolation voltage rating and test standard for ISO122PE4?

The ISO122PE4 is rated for 1500 V_rms continuous isolation voltage and 100% tested to 2400 V_rms for 1 second with <5 pC partial discharge per VDE 0884-compliant methodology. This confirms transient overvoltage immunity up to 1.6× rated voltage without degradation - a requirement verified on every production unit, not just sample lots. The ISO122PE4 meets IEC 60747-5-2 for reinforced insulation in industrial systems.

Does ISO122PE4 support single-supply operation on either side?

The ISO122PE4 requires dual ±4.5 V to ±18 V supplies on both high-side (VS1) and low-side (VS2) domains - it does not support true single-supply operation. However, the high-side section can be powered from a single positive rail using an external Zener or charge-pump circuit to generate the required negative supply, as documented in TI SBOA004. The ISO122PE4 itself must always see symmetric rails to maintain specified linearity and offset performance.

What is the maximum input voltage range for ISO122PE4, and how is it related to supply voltage?

The ISO122PE4 accepts a maximum input voltage of ±12.5 V regardless of supply voltage, with guaranteed ±10 V linear output swing. The input is a current node (200 kΩ input resistance), so input voltage compliance is independent of VS1 magnitude - enabling inputs exceeding the ±4.5 V minimum supply rails. However, full ±10 V output swing requires ±15 V supplies; at ±4.5 V, output swing reduces to ±2 V as specified in the Recommended Operating Conditions table of the ISO122PE4 datasheet.

How does ISO122PE4 handle high-frequency common-mode transients (dV/dt)?

The ISO122PE4 exhibits robust dV/dt immunity up to 1000 V/µs due to its digital duty-cycle modulation scheme and matched capacitive barrier. Above this threshold, the sense amplifier may false-trigger, introducing spurious output errors. TI recommends reducing supply voltages below ±15 V (e.g., to ±12 V) to lower slew rate, or adding external RC filtering on supply pins - both validated in ISO122PE4 application note SBOS160A. The device's 140 dB IMR at 60 Hz further suppresses lower-frequency interference.

Can ISO122PE4 be used with thermocouples without external cold-junction compensation?

No - the ISO122PE4 provides only galvanic isolation and unity-gain amplification; it does not include cold-junction compensation (CJC) circuitry. For thermocouple use, ISO122PE4 must be paired with a dedicated CJC front-end such as the INA101 (as shown in Figure 19 of SBOS160A), which conditions the thermocouple output and compensates for reference-junction temperature before feeding VIN. The ISO122PE4 then isolates that conditioned signal, preserving accuracy while breaking ground loops.