LS844 TO-71 6L ROHS

Overview

The LS844 TO-71 6L is a monolithic dual N-channel JFET amplifier from Linear Integrated Systems. It features ultra-low noise of 2.5nV/√Hz at 1kHz and very low gate leakage of 15pA typical. The device offers high common-mode rejection ratio (CMRR) up to 102dB, low offset voltage of 5mV max, and minimal drift of 5µV/°C max. Input capacitance is exceptionally low at 3pF typical, reducing intermodulation distortion. It operates within a junction temperature range of -55°C to +150°C with a maximum power dissipation of 400mW.

Feature Summary

• Ultra-low input capacitance significantly reduces intermodulation distortion compared to standard JFETs.
• Monolithic construction provides excellent matching and thermal tracking between the two JFET channels.
• High slew rate and high CMRR ensure improved op amp speed settling time accuracy.
• Low gate leakage and low offset voltage minimize input error trimming requirements.

Applications

• Wideband differential amplifiers
• High-speed temperature compensated single-ended input amplifiers
• High-speed comparators
• Impedance converters
• Sonobuoys and hydrophones

Procurement Notes

Verify the specific package type matches the required application, as the LS844 series is available in multiple formats including TO-71 6L, TO-78 6L, SOT-23 6L, SOIC 8L, and PDIP 8L. Confirm RoHS compliance status if environmental regulations apply. Ensure the ordering suffix aligns with the desired lead frame or plating finish if specified by the manufacturer's custom part call-out options.

Selection Notes

Select the LS844 over the LSK389 when lower gate-to-drain capacitance is critical for circuit performance, despite a slightly higher noise profile. The TO-71 6L package is pin-compatible with the LSK389, facilitating direct upgrades. Consider the LS845 variant if looser offset voltage specifications are acceptable for cost reduction. Evaluate the trade-off between the low capacitance benefits and the specific noise requirements of the target application.

Part Context

The LS844 Series represents an advancement in low-noise JFET technology by combining low noise levels comparable to the LSK389 with substantially lower gate-to-drain capacitance. This unique combination allows for simpler circuit designs with fewer devices. The interleaved design on a single silicon piece ensures tight differential voltage match and low drift, targeting precision instrumentation and sensor applications where signal integrity is paramount.

Replacement Considerations

The LS844 TO-71 6L is fit, form, and pin compatible with the LSK389 product in the same package. For equivalent single N-channel versions, refer to the LSK189 datasheet. Designers upgrading from the LSK389 should note the slight increase in noise but gain significant reductions in input capacitance.

FAQ

How does the LS844 compare to the LSK389 regarding capacitance?

The LS844 has a much lower gate-to-drain capacitance of approximately 4pF compared to the 25pF found in the LSK389, which helps reduce intermodulation distortion.

What is the typical input bias current for this device?

The typical gate leakage current (IGSS) is 15pA at full conduction conditions, contributing to very low input bias current characteristics.

Is the LS844 suitable for high-frequency applications?

Yes, the device features a high slew rate and low input capacitance, making it suitable for wideband differential amplifiers and high-speed comparators.