Texas Instruments 3650HG

Overview

3650HG from Texas Instruments (formerly Burr-Brown) is an optically coupled linear isolation amplifier designed for high-precision, high-common-mode-voltage signal conditioning in industrial and biomedical systems. It delivers ±2000V continuous isolation, 140dB isolation-mode rejection at DC, 0.05% linearity, 15kHz bandwidth, and operates with ±8V to ±18V dual supplies. It is used in current shunt measurement and ground-loop elimination where galvanic separation and analog fidelity are critical.

For engineers reviewing the 3650HG datasheet, 3650HG pinout, 3650HG application, or 3650HG equivalent, this page provides verified technical context, validated pin functions, real-world use scenarios, and two confirmed alternative parts - all grounded in the official SBOS129 datasheet and TI packaging documentation.

Technical Context

The 3650HG uses a dual-photodiode optical coupling architecture with DC analog modulation to eliminate carrier-related EMI issues found in transformer-based isolators. Its input stage accepts differential current or voltage sources via user-configurable gain-setting resistors (RG1/RG2), while its output stage delivers ±10V swing with ±5mA drive capability.

It features balanced input topology with 25Ω max differential input impedance, 10⁹Ω common-mode input impedance, and achieves 120dB CMR at 60Hz with 5kΩ source imbalance. The device supports operation from –40°C to +100°C and requires isolated ±15V supplies for both input and output stages.

Key Specifications

Pinout & Package

3650HG is housed in a 32-pin Ceramic Dual In-line Package (CDIP) with JNC drawing, rated for military-grade reliability and hermetic sealing. Pin numbering follows standard DIP convention with notch-up orientation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISO124 and AMC1301, the 3650HG offers superior continuous isolation voltage (±2000V vs ≤±1500V) and true analog voltage output - making it irreplaceable in legacy high-voltage analog feedback loops where signal chain continuity is mandatory.

Availability

3650HG is available at Aetrix Electronics and suitable for industrial process control, patient monitoring, SCR controls, and current shunt measurement requiring stable component supply amid extended product lifecycles.

Supply support for 3650HG 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 delivering analog, embedded processing, and connectivity solutions with deep heritage in precision analog design.

The 3650HG belongs to TI's legacy Burr-Brown linear isolation amplifier family, engineered specifically for high-fidelity, high-isolation analog signal transmission in safety-critical industrial and medical instrumentation.

FAQ

What is the maximum continuous common-mode voltage the 3650HG can withstand?

The 3650HG supports ±2000V continuous isolation voltage across its barrier, verified per UL 1577 and tested at 5000Vpk for 10 seconds. This rating applies to the voltage difference between input and output commons (VISO), not differential input voltage. Operation beyond ±2000V requires external protection networks, as specified in the SBOS129 datasheet section "Guarding and Protection".

Does the 3650HG require external gain-setting resistors, and how are they configured?

Yes, the 3650HG requires external gain-setting resistors. For voltage-source inputs, RG1 and RG2 are connected to the ±I pins to set gain per GV1 = VOUT/(V1–V2); for current-source inputs, RG is placed between ±I and input common to achieve G1 = 10⁶ V/A. The 3650HG datasheet specifies RG1 + RG2 + RIN ≤ 1.06 MΩ for stability, and recommends matched values to minimize bias-current-induced errors.

Can the 3650HG be used with a single-ended input, or is differential operation mandatory?

The 3650HG is optimized for differential input operation but supports single-ended use. When using a single voltage source, the gain-setting resistor should be split equally between +I and –I pins to preserve common-mode rejection and minimize bias-current errors. The SBOS129 datasheet explicitly warns that unbalanced RG configurations degrade CMR and increase offset drift - so symmetric layout is required even in single-ended configurations.

What is the purpose of the BAL pins on the 3650HG, and how are they used?

The 3650HG has two independent BAL terminals: one for input-stage offset null (pins 15/16, 50kΩ pot) and one for output-stage offset null (pins 13/14, 10kΩ pot). These are optional - the device meets all specifications without connection. For best accuracy, null the input stage first at maximum gain, then the output stage at minimum gain. Both adjustments affect total output error, and the SBOS129 datasheet provides detailed procedure in "Offset Voltage Adjustments".

Is the 3650HG still in active production, and what is its lifecycle status?

The 3650HG is marked NRND (Not Recommended for New Designs) per TI's official packaging addendum, indicating it remains in production solely to support existing customer programs. TI does not recommend it for new designs due to obsolescence trajectory, though Aetrix Electronics maintains inventory and offers lifecycle coordination services including last-time buy planning and cross-reference guidance for migration paths.