LT1720CDD#TRPBF

Overview

The LT1720CDD#TRPBF is a dual, ultrafast comparator optimized for single-supply operation within a 2.7V to 6V range. It features rail-to-rail outputs compatible with TTL and CMOS logic levels. The device operates with a supply current of 4mA per comparator at 5V and achieves a propagation delay of 4.5ns at 20mV overdrive. Input voltage ranges extend from 100mV below ground to 1.2V below the positive supply rail. Internal hysteresis ensures stable performance with slow-moving signals.

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
• Input common-mode range extends 100mV below the negative supply rail
• Integrated internal hysteresis prevents oscillation with slow input signals

Applications

• Crystal oscillator circuits
• High-speed differential line receivers
• Window comparators
• Threshold detectors and discriminators
• Zero-crossing detectors

Procurement Notes

Verify the specific ordering suffix #TRPBF confirms tape and reel packaging when sourcing components. Confirm the C grade designation indicates an operating temperature range of 0°C to 70°C. Ensure the DFN package type matches the required footprint for space-limited applications. Cross-reference the manufacturer's latest documentation for any updates to lead-free finish specifications or marking codes before finalizing procurement orders.

Selection Notes

Select this component for designs requiring high speed and low power consumption in single-supply systems. The rail-to-rail output capability simplifies interfacing with standard digital logic families without additional level shifting circuitry. The wide common-mode input range allows for signal detection near the ground potential. Consider the internal hysteresis for noise immunity, though external feedback may be added if higher thresholds are required.

Part Context

This part belongs to the LT1720/LT1721 family of UltraFast comparators manufactured by Analog Devices Inc. (formerly Linear Technology). The LT1720 variant provides two independent comparators in compact packages including the 3mm x 3mm DFN. The family is designed for applications where small size and low power are critical constraints while maintaining high-speed signal processing capabilities.

Replacement Considerations

LT1720CDD#PBF: Same electrical specifications and functionality; differs only in bulk tube packaging instead of tape and reel.

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, ensuring stable switching behavior.

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

Phase reversal protection circuitry prevents false output inversion down to at least -400mV common mode. However, offset and hysteresis values increase significantly in this state, and input bias currents also rise.