LSK489A SOIC 8L ROHS

Overview

The LSK489A is a monolithic dual N-Channel JFET amplifier featuring industry-low input capacitance and low noise. It offers an input capacitance of 4pF and a noise voltage of 1.8nV/√Hz at 1kHz. The device provides high CMRR of 102dB and tight differential matching with ΔIDSS of 6mA for Grade A. Gate-to-source breakdown voltage is rated at 60V, while gate-to-gate breakdown reaches ±45V. Transconductance typically measures 1500µS. Operating temperatures range from -55°C to +150°C junction temperature.

Feature Summary

• Monolithic dual N-Channel JFET construction providing excellent thermal tracking and matching.
• Ultra-low common source input capacitance significantly reduces intermodulation distortion.
• Tight differential voltage match and low offset drift over the operating temperature range.
• High common mode rejection ratio ensuring precision signal amplification.

Applications

• Wideband differential amplifiers
• High-speed temperature compensated single-ended input amplifiers
• Sonobuoys and hydrophones
• Acoustic sensors

Procurement Notes

Verify the specific grade designation (A or B) required for your design, as IDSS ranges differ between grades. Confirm package availability matches the SOIC 8L requirement. Ensure supply chain sources provide original manufacturer documentation to validate component authenticity and revision status before integration into production systems.

Selection Notes

Select this component when minimizing input capacitance is critical for reducing intermodulation distortion in high-frequency circuits. Choose the LSK489A over the LSK389 if lower capacitance outweighs the marginal increase in noise voltage. Verify that the required IDSS matching tolerance aligns with the specified Grade A limits for optimal circuit performance.

Part Context

This device belongs to the LSK489 series of low-noise, low-capacitance dual JFETs manufactured by Linear Integrated Systems. It serves as a surface-mount alternative to through-hole variants, offering pin compatibility with the LSK389 family in SOIC packages. The technology targets precision instrumentation where signal integrity and minimal parasitic effects are paramount.

Replacement Considerations

The LSK489 SOIC 8L package is fit, form, and pin compatible with the LSK389 product. Designers may substitute the LSK389 directly without schematic changes. For single-channel requirements, the LSK189 serves as the equivalent single N-Channel version within the same product family.

FAQ

How does the LSK489 compare to the LSK389 regarding capacitance?

The LSK489 features a much lower gate-to-drain capacitance of 4pF compared to the 25pF found in the LSK389, enabling simpler circuit designs with reduced intermodulation distortion.

What is the difference between LSK489A and LSK489B grades?

The primary difference lies in the drain saturation current matching. The LSK489A has a tighter ΔIDSS limit of 6mA, whereas the LSK489B allows a ΔIDSS of 7mA.

Is the LSK489 suitable for acoustic sensor applications?

Yes, the datasheet explicitly lists sonobuoys, hydrophones, and acoustic sensors as target applications due to the device's low noise profile and tight matching characteristics.