LT1720IDD#TRPBF

Overview

The LT1720IDD#TRPBF is a dual ultrafast comparator from Analog Devices, optimized for single-supply operation within 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 ensure stability with slow-moving input signals. Key electrical specifications include a propagation delay of 4.5ns at 20mV overdrive and a quiescent supply current of 4mA per comparator. The common-mode input voltage range extends from 100mV below ground to 1.2V below the positive supply rail.

Feature Summary

• Ultrafast response time with 4.5ns propagation delay at 20mV overdrive
• Rail-to-rail output stage directly interfaces with TTL and CMOS logic
• Internal hysteresis prevents oscillation and ensures stable switching
• Input voltage 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
• High-speed sampling circuits

Procurement Notes

Verify the specific package type and temperature grade when ordering. The IDD suffix indicates an industrial temperature range (-40°C to +85°C) and tape-and-reel packaging. Confirm that the required lead finish matches the datasheet specifications for the intended manufacturing process. Ensure compatibility with the target PCB footprint for the 8-lead DFN package.

Selection Notes

Select this component for applications requiring high speed and low power consumption in single-supply systems. The internal hysteresis simplifies design by reducing susceptibility to noise on slow-moving signals. Consider the input bias current direction and magnitude when designing source impedance networks. Verify that the load capacitance does not significantly degrade the propagation delay performance.

Part Context

This part belongs to the LT1720/LT1721 family of UltraFast comparators. The LT1720 variant provides two independent comparators in an 8-pin package, while the LT1721 offers four channels. Both families share similar electrical characteristics but differ in channel count and available package options such as MSOP, SO, and DFN.

Replacement Considerations

LT1720CDD#TRPBF: Same function with commercial temperature range (0°C to 70°C).

FAQ

How does the internal hysteresis affect the trip points?

The internal hysteresis creates distinct upper and lower trip points. The offset voltage is defined as the average of these two points, while the hysteresis voltage is the difference between them.

What happens if both inputs go below the negative common mode limit?

Phase reversal protection circuitry prevents false output inversion down to -400mV common mode, though offset and hysteresis may increase significantly in this state.