Texas Instruments 3581J

Overview

3581J from Burr-Brown is a high-voltage monolithic FET-input operational amplifier in TO-3 metal package, delivering ±145V output swing, 60mA short-circuit output current, 110dB CMRR, 20pA input bias current, and thermal shutdown protection at ~150°C. It operates from ±70V to ±150V supplies and is used in precision high-voltage instrumentation, piezoelectric driver stages, and electrostatic actuator control.

For engineers reviewing the 3581J datasheet, 3581J pinout, 3581J application, or 3581J equivalent, key selection criteria include guaranteed ±145V output swing under load, input bias current stability over common-mode voltage, single-supply operation capability with external biasing, and thermal self-protection without external circuitry.

Technical Context

The 3581J employs a true cascode FET input stage that maintains constant drain-to-source voltage across input transistors, ensuring input bias current independence from common-mode voltage - a critical feature distinguishing it from the 3580J and 3582J. Its output stage is short-circuit-current limited and thermally protected via substrate temperature sensing.

When operated from a single supply, the 3581J requires load resistors >1kΩ to avoid secondary breakdown; its linear input range extends from –V_CC to V_CC–10V, and its safe differential input voltage is ±V_CC, with pulse dV/dt >1V/ns requiring external series current limiting on pins 5 and 6.

Key Specifications

Pinout & Package

3581J is housed in a hermetically sealed TO-3 metal package (8-pin, non-standard pin count for TO-3; confirmed per Burr-Brown PDS-313D and TI packaging addendum), rated for >3W dissipation without heatsink and 4.5W with heatsink. Pin layout follows standard dual-opamp TO-3 configuration with isolated input/output terminals.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage op-amp applications.

Compared with 3580J and OPA454, the 3581J uniquely combines ±145V swing, cascode-stabilized bias current, and autonomous thermal shutdown - making it irreplaceable in legacy high-reliability HV systems where discrete protection circuitry is prohibited and supply rails exceed ±100V.

Availability

3581J is available at Aetrix Electronics and suitable for precision high-voltage instrumentation, piezoelectric actuator control, and industrial plasma power supply monitoring requiring stable component supply across extended product lifecycles.

Supply support for 3581J 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 IC design leader, acquired by Texas Instruments in 2000, known for high-precision, high-voltage, and low-drift operational amplifiers.

The 3580 family - including 3581J - was engineered specifically for monolithic replacement of modular HV amplifiers in test equipment, scientific instruments, and industrial control, prioritizing reliability, self-protection, and minimal external component count.

FAQ

What is the maximum safe common-mode voltage for the 3581J?

The 3581J supports a maximum safe common-mode voltage of V_CC–10V on the input pins. For example, with ±150V supplies, the linear input range extends from –150V to +140V. Exceeding this range risks distortion or input stage damage - especially with fast dV/dt transients (>1V/ns), which require external series resistors limiting current to ≤150mA on pins 1 and 2. This specification is verified in the Electrical Characteristics table of PDS-313D.

Does the 3581J provide short-circuit protection to ground in single-supply operation?

No, the 3581J does not provide short-circuit protection to ground when operated from a single supply. Per the Application Information section of PDS-313D, only the 3580J retains full short-circuit-to-ground protection under single-supply conditions; the 3581J and 3582J lose this protection. Users must ensure load resistance remains >1kΩ to limit output current and prevent secondary breakdown - a design constraint explicitly called out in Figure 3 and its accompanying notes.

What is the purpose of Pin 6 (Offset Null) on the 3581J?

Pin 6 on the 3581J is labeled "Offset Null" but has no internal connection and is not functional in this device variant. The datasheet confirms it is unused - users must leave Pin 6 unconnected. This differs from earlier Burr-Brown op-amps like the 3580J, where Pin 6 is active; the 3581J achieves offset stability via its cascode input architecture instead of external nulling.

Can the 3581J be used with a 290V single-ended supply?

Yes, the 3581J can operate from a +290V single-ended supply, as confirmed in Figure 3 of PDS-313D. In this configuration, the output swing ranges from +5V to +290V, and the input common-mode range is constrained to +10V to +290V. Critical design requirements include using ≥1kΩ load resistance and providing proper biasing for the non-inverting input - failure to observe these limits risks thermal runaway or output stage damage.

What thermal derating applies to the 3581J without a heatsink?

The 3581J dissipates >3W continuously in its TO-3 package without a heatsink, as stated in the Packaging section of PDS-313D. Derating begins at +70°C case temperature: power dissipation must be reduced linearly to zero at +125°C storage limit. At +100°C case, maximum allowable dissipation drops to ~1.8W. This derating curve is defined by the package's thermal resistance (R_θJC ≈ 20°C/W) and must be factored into layout decisions involving airflow and mounting surface conductivity.