Texas Instruments ISO120G-BI

Overview

ISO120G-BI from Burr-Brown Corporation is a precision isolation amplifier employing duty-cycle modulation across a 2pF differential capacitive barrier, delivering 0.01% max nonlinearity, 115dB IMR at 60Hz, and ±10V bipolar output swing. It operates over ±4.5V to ±18V supplies with 6kHz bandwidth (with C1=C2=1000pF) and is used in industrial transducer isolation, 4–20mA loop systems, and biomedical signal conditioning where galvanic separation and high common-mode rejection are critical.

For engineers reviewing the ISO120G-BI datasheet, ISO120G-BI pinout, ISO120G-BI application, or ISO120G-BI equivalent, key selection considerations include its 1500Vrms isolation rating, hermetic 24-pin DIP package, guaranteed VOS drift ≤150µV/°C, synchronization capability via Ext Osc pin, and compatibility with ±10V input/output ranges under wide temperature operation (–25°C to +85°C).

Technical Context

The ISO120G-BI implements a laser-trimmed, dual-section architecture: an input integrator (A1) converts VIN into a duty-cycle-modulated triangular waveform using internal 150pF and external C1 capacitors; the modulated signal crosses the 2pF capacitive barrier and is demodulated by a matched output section (A2) with sample-and-hold filtering to suppress ripple. Its free-running carrier frequency is ~500kHz when C1 = 0, yielding 60kHz small-signal bandwidth.

In synchronized mode, an external ±4V sine or triangle wave applied to the Ext Osc pin (Pin 22) locks the modulator frequency - enabling noise rejection at system clock harmonics - while requiring C1/C2 ≥ 500pF for stability below 400kHz. The device maintains charge balance around A1 and A2 via 200kΩ feedback paths, ensuring gain accuracy of ±0.1% FSR and IMR performance independent of barrier impedance.

Key Specifications

Pinout & Package

ISO120G-BI is housed in a 0.3"-wide 24-pin hermetic dual-in-line package (DIP), rated for operation from –25°C to +85°C and qualified for high-reliability applications requiring partial discharge testing (≤5pC at 2500Vrms).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISO120G-BI, ISO120BG offers identical electrical performance but reduced quality assurance rigor, while AMC1301DWV delivers higher isolation and smaller footprint at the expense of programmable carrier control, hermetic reliability, and direct ±10V output compatibility.

Availability

ISO120G-BI is available at Aetrix Electronics and suitable for industrial process control, motor drive feedback, and biomedical instrumentation requiring stable component supply, long-term obsolescence management, and traceable sourcing from original manufacturer-qualified channels.

Supply support for ISO120G-BI 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

Burr-Brown Corporation was a U.S.-based analog semiconductor pioneer (acquired by Texas Instruments in 2000), renowned for high-precision signal conditioning ICs used in test equipment, medical devices, and industrial automation.

The ISO120G-BI belongs to Burr-Brown's precision isolation amplifier product line, designed specifically for applications demanding galvanic separation, ultra-low drift, and immunity to high dv/dt transients in electrically noisy environments.

FAQ

What is the maximum continuous isolation voltage rating for ISO120G-BI?

The ISO120G-BI is rated for 1500Vrms continuous AC isolation voltage at 60Hz across its capacitive barrier. This rating is validated by 100% production partial discharge testing at 2500Vrms for 1 second with ≤5pC discharge level - confirming robust dielectric integrity for use in industrial mains-referenced systems. The ISO120G-BI also supports 2121VDC continuous rating per specification table.

Can ISO120G-BI operate with ±12V supplies instead of ±15V?

Yes, ISO120G-BI supports supply voltages from ±4.5V to ±18V, making ±12V fully compliant. At ±12V, output swing remains ±10V (limited by internal design), and specifications such as nonlinearity (±0.01% max), IMR (115dB at 60Hz), and VOS drift (≤150µV/°C) are maintained per datasheet conditions. Quiescent current decreases slightly, improving thermal margin in compact layouts.

How does the Ext Osc pin on ISO120G-BI enable noise rejection?

The Ext Osc pin (Pin 22) allows external synchronization of the ISO120G-BI's internal carrier frequency to system clocks or noise sources. By locking the modulator to a known frequency (e.g., 100kHz), the ISO120G-BI places its response nulls at that frequency and harmonics - effectively attenuating periodic interference from DC/DC converters or digital clocks. This requires matching C1 and C2 values per the Synchronization Range curve.

What is the purpose of the Sense pin on ISO120G-BI?

The Sense pin (Pin 15) on ISO120G-BI provides Kelvin sensing for the output stage, allowing remote sensing at the load to eliminate errors from IR drops in output traces or connectors. When connected directly to VOUT, it enables standard unity-gain operation; when routed to the load terminal, it compensates for voltage loss - critical for maintaining ±10V accuracy in long-cable 4–20mA loop drivers or precision actuator interfaces.

Is ISO120G-BI compatible with C1 = C2 = 0 for maximum bandwidth?

Yes, ISO120G-BI achieves 60kHz small-signal bandwidth with C1 = C2 = 0, using its internal 150pF modulator and demodulator capacitors. However, this configuration yields higher nonlinearity (±0.02% max) and VOS drift (±250µV/°C), and removes synchronization capability. For precision applications, C1 = C2 = 1000pF is recommended to guarantee ±0.01% nonlinearity and ≤150µV/°C drift at 6kHz bandwidth.