LT1720IS8

Overview

The LT1720IS8 is a dual, high-speed comparator optimized for single-supply operation with a voltage range of 2.7V to 6V. It features rail-to-rail outputs compatible with TTL and CMOS logic levels. The device includes internal hysteresis to handle slow-moving input signals effectively. Propagation delay is specified at 4.5ns with 20mV overdrive and 7ns with 5mV overdrive. Quiescent supply current is 4mA per comparator. The component is housed in an 8-lead plastic SO package.

Feature Summary

• UltraFast propagation delay performance for high-speed signal processing
• Rail-to-rail output stage directly interfaces with standard logic families
• Internal hysteresis ensures stable operation with noisy or slow input transitions
• Input common-mode range extends 100mV below the negative supply rail

Applications

• Crystal oscillator circuits
• High-speed differential line receivers
• Window comparators and threshold detectors
• Zero-crossing detectors
• Pulse stretchers and sampling circuits

Procurement Notes

Verify the specific suffix IS8 corresponds to the 8-lead Plastic SO package and Industrial temperature grade (-40°C to 85°C). Confirm lead-free finish requirements match project specifications. Check for RoHS compliance status as manufacturing processes may vary by production batch. Ensure ordering information aligns with current datasheet revisions to avoid pinout or electrical characteristic discrepancies.

Selection Notes

Select this component when low power consumption and high speed are critical within a single-supply system. The internal hysteresis simplifies design by reducing the need for external feedback components. Verify that the input signal amplitude and source impedance do not cause excessive delay due to input capacitance. Ensure the load current requirements remain within the output drive capabilities of the rail-to-rail stage.

Part Context

This part belongs to the UltraFast comparator family from Analog Devices. It shares architectural similarities with the quad LT1721 variant but offers a dual configuration in a compact 8-lead form factor. The series is designed for applications requiring precise timing and fast response times while maintaining low static power dissipation compared to older bipolar comparator technologies.

Replacement Considerations

LT1720CS8#PBF (Commercial Grade)

FAQ

How does the internal hysteresis affect the trip points?

The internal hysteresis creates two distinct trip points: one for rising inputs and one for falling inputs. This prevents output oscillation when the input signal is near the threshold, ensuring a clean logic transition even with slowly moving signals.

What is the behavior if the input voltage exceeds the positive common-mode limit?

If both inputs exceed the positive common-mode limit, the input stage becomes debiased and the output polarity may become random. However, the internal hysteresis maintains the output at a valid logic level until at least one input returns to the valid common-mode range.