Analog Devices Inc. AD590LF

Overview

AD590LF from Analog Devices is a 2-terminal IC temperature transducer that outputs a linear current of 1 μA/K across −55°C to +150°C, housed in a probe-compatible ceramic FLATPACK package with ±0.5°C calibration accuracy at 25°C and high-impedance current output for remote sensing applications.

For engineers reviewing the AD590LF datasheet, AD590LF pinout, AD590LF application, or AD590LF equivalent, key selection considerations include its 2-terminal voltage-in/current-out architecture, laser-trimmed absolute temperature response, immunity to supply voltage drift (≤0.1 μA/V above 15 V), case isolation >10¹⁰ Ω, and suitability for multiplexed, long-line, or thermally isolated measurement systems.

Technical Context

The AD590LF implements a PTAT (Proportional-To-Absolute-Temperature) current regulation architecture using matched silicon transistors and laser-trimmed thin-film resistors to generate a precise 1 μA/K output. Its two-terminal configuration eliminates need for biasing circuitry or cold-junction compensation.

It operates as a high-impedance (>10 MΩ) current source over 4 V–30 V supply range, with forward voltage tolerance up to 44 V and reverse voltage rating of −20 V. Output current remains stable across supply variations due to low power supply rejection (0.1 μA/V at 15–30 V).

Key Specifications

Pinout & Package

AD590LF uses a 2-lead ceramic FLATPACK (F-2) package with hermetically sealed construction and probe-compatible form factor. The device has no internal ground or reference pin-both terminals are active: one serves as current input (V+), the other as current return (V−).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 2-terminal temperature transducer applications.

Compared with LM335AZ and TSIC 506, the AD590LF delivers superior long-distance accuracy via current-mode signaling, eliminates support components like excitation sources or level shifters, and provides monolithic interchangeability without host processor dependency-making it optimal for ruggedized analog temperature telemetry.

Availability

AD590LF is available at Aetrix Electronics and suitable for remote industrial monitoring, cold junction compensation, multiplexed sensor arrays, and thermostat control requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD590LF 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

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.

The AD590LF belongs to Analog Devices' precision temperature transducer product line, engineered specifically for applications demanding absolute-temperature accuracy, electrical robustness, and simplified analog interface-especially where lead-wire effects, supply instability, or thermal isolation challenge conventional sensors.

FAQ

What is the pin configuration of the AD590LF?

The AD590LF uses a 2-lead ceramic FLATPACK package with no internal ground or reference pin. Terminal 1 (V+) accepts the supply voltage (4–30 V), and Terminal 2 (V−) delivers the temperature-proportional current output. Both leads are electrically active, and polarity reversal up to −20 V is tolerated without damage. No NC pins or exposed pads are present in this variant.

How does the AD590LF achieve ±0.5°C accuracy at 25°C?

The AD590LF achieves ±0.5°C calibration accuracy at 25°C through wafer-level laser trimming of thin-film resistors that set the PTAT current gain. This process adjusts the output to precisely 298.2 μA at 298.2 K (25°C) before packaging and final test. The AD590LF grade is specified to meet this tolerance, distinguishing it from lower-grade variants like AD590J (±5.0°C).

Can the AD590LF be used with unregulated power supplies?

Yes, the AD590LF operates reliably with unregulated supplies from 4 V to 30 V due to its low power supply rejection-only 0.1 μA/V change in output current above 15 V. This allows direct connection to rectified AC rails or battery banks without regulators or filtering capacitors, provided minimum voltage stays above 4 V under load.

What is the maximum cable length supported for remote sensing with the AD590LF?

The AD590LF supports remote sensing over hundreds of feet using standard twisted-pair wiring. Its high-impedance current output rejects voltage drop and EMI, and its 1 μA/K scaling ensures measurable signal integrity even with line resistance exceeding 1 kΩ. Performance is validated in field deployments up to 500 ft with 24 AWG twisted pair and proper shielding.

Does the AD590LF require external linearization circuitry?

No, the AD590LF does not require external linearization. Its inherent nonlinearity is limited to ±0.3°C over −55°C to +150°C (AD590LF grade), and its 1 μA/K transfer function is intrinsically proportional to absolute temperature. Linear voltage output can be achieved with a single precision resistor (e.g., 1 kΩ → 1 mV/K), eliminating op-amps, trim pots, or lookup tables.