Texas Instruments ISO122P

Overview

ISO122P from Texas Instruments is a precision analog isolation amplifier featuring galvanic isolation via embedded 2-pF differential capacitive barrier, 1500 V_rms continuous isolation rating, 140 dB IMR at 60 Hz, ±10 V output swing, and 50 kHz small-signal bandwidth. It operates with dual ±4.5 V to ±18 V supplies on both sides and is used in industrial transducer signal conditioning where ground-loop elimination and high common-mode transient immunity are required.

For engineers reviewing the ISO122P datasheet, ISO122P pinout, ISO122P application, or ISO122P equivalent, this page delivers verified technical context for isolated analog signal transmission in process control, motor control, and test equipment - including confirmed supply range, nonlinearity (±0.020% FSR), thermal resistance (51.0 °C/W), and single-supply operation capability using external Zener biasing per SBOA004.

Technical Context

The ISO122P uses duty-cycle modulation-demodulation across a matched capacitive barrier, with input section integrating VIN/200 kΩ against a switched ±100 mA current source clocked at 500 kHz. Its modulator generates a complementary square wave drive for robust digital transmission unaffected by barrier capacitance variation.

The demodulator employs a sense amplifier to detect barrier transitions, driving integrator A2 to reconstruct VIN at VOUT while sample-and-hold stages suppress 500 kHz ripple. Laser-trimmed circuitry ensures <±20 mV initial input offset and <±200 µV/°C drift, enabling precision DC-coupled isolation without external gain-setting components.

Key Specifications

Pinout & Package

ISO122P is supplied in a 16-pin plastic DIP (PDIP-NVF) package measuring 17.90 mm × 7.50 mm, with creepage and clearance optimized for reinforced isolation. Pin 1 is +VS1; pin 2 is –VS1; pin 7 is VOUT; pin 8 is GND2 (low-side ground); pin 15 is VIN; pin 16 is GND1 (high-side ground); pins 9 and 10 are +VS2 and –VS2 respectively.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISO122P, ISO124P trades bandwidth and simplicity for higher isolation and linearity, while AMC1301DWVR replaces analog output with a digital bitstream - requiring redesign of downstream signal processing and eliminating compatibility with legacy analog ADCs or meters.

Availability

ISO122P is available at Aetrix Electronics and suitable for industrial process control, motor control, and PC-based data acquisition requiring stable component supply across extended product lifecycles.

Supply support for ISO122P 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 leader specializing in analog and embedded processing technologies, with over 50 years of innovation in precision signal conditioning and isolation solutions.

The ISO122P belongs to TI's precision isolation amplifier product line, engineered specifically for cost-sensitive industrial applications demanding reliable galvanic isolation, low nonlinearity, and ease of use without external gain components.

FAQ

What is the maximum continuous isolation voltage rating for the ISO122P?

The ISO122P is rated for 1500 V_rms continuous isolation voltage per UL1577 and IEC 60747-5-2 standards. Every unit undergoes 100% production testing at 2400 V_rms for 1 second with ≤5 pC partial discharge - confirming robustness against transient overvoltages up to 1.6× rated voltage without degradation. This rating applies to the full operating temperature range of –25°C to +85°C.

Can the ISO122P operate from a single supply on the high-voltage side?

Yes, the ISO122P supports single-supply operation on the high-voltage side using external circuitry such as a 5.1-V Zener diode to generate –VS1, as documented in Application Note SBOA004 and Figure 21 of the ISO122 datasheet. Input range adjusts per supply voltage (e.g., –2 V to +10 V with +20 V supply), and performance remains within datasheet specifications including nonlinearity and bandwidth.

What is the purpose of the two separate ground pins (GND1 and GND2) on the ISO122P?

GND1 (Pin 16) is the high-side ground reference for VIN and –VS1, while GND2 (Pin 8) is the low-side ground reference for VOUT and –VS2. These pins define the isolation boundary: no conductive path may exist between them on PCB layout. Maintaining physical separation preserves the 1500 V_rms isolation rating and prevents leakage current from degrading IMR performance.

Does the ISO122P require external components for basic operation?

No, the ISO122P is a fixed unity-gain isolation amplifier requiring no external gain-setting resistors or compensation networks. Only supply bypassing (1-µF tantalum per VS pin, placed close to the package) is mandatory. Optional external components include a 2-pole low-pass filter to suppress 500 kHz output ripple or Zener diodes for single-supply high-side biasing - but these are application-specific, not functional prerequisites.

How does the ISO122P handle input signals above 250 kHz?

The ISO122P uses 500 kHz duty-cycle modulation, making it behave like a sampling system for inputs >250 kHz. Per the Nyquist criterion, such signals produce aliased outputs at lower frequencies (e.g., a 300 kHz input yields a 200 kHz alias). The "Signal Response to Inputs Greater Than 250-kHz" curve (Figure 9) quantifies this effect. For faithful reproduction, input signals must remain below 250 kHz - aligning with its 50 kHz small-signal bandwidth specification.