LT1720IDD#PBF

Overview

The LT1720IDD#PBF is a dual ultrafast comparator from Analog Devices, housed in an 8-lead 3mm × 3mm plastic DFN package. It operates on a single supply voltage ranging from 2.7V to 6V. The device features rail-to-rail outputs compatible with TTL and CMOS logic levels. Key electrical specifications include a propagation delay of 4.5ns at 20mV overdrive and 7ns at 5mV overdrive. Supply current is typically 4mA per comparator. The input common mode range extends from 100mV below ground to 1.2V below the positive supply rail.

Feature Summary

• Ultrafast response time optimized for high-speed signal processing applications
• Rail-to-rail output stage directly interfaces with standard digital logic families
• Internal hysteresis ensures stable operation with slow-moving input signals
• Input voltage range includes negative excursion capability below the ground rail

Applications

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

Procurement Notes

Verify the specific suffix IDD#PBF confirms the industrial temperature grade (-40°C to 85°C) and lead-free finish. Confirm the 8-lead DFN package dimensions match the design constraints. Ensure the ordering code corresponds to the tube packaging format rather than tape and reel variants.

Selection Notes

Select this component when low power consumption and small footprint are critical alongside high speed. The internal hysteresis simplifies circuit design by reducing noise sensitivity without external components. Verify that the required propagation delay meets the system timing budget under the specific load capacitance conditions.

Part Context

This part belongs to the LT1720/LT1721 family of ultrafast comparators designed for single-supply operation. The LT1720 provides two comparators in compact packages, while the LT1721 offers four channels. Both series share identical electrical characteristics and pinout optimizations for minimizing parasitic effects in high-speed layouts.

Replacement Considerations

LT1720CDD#PBF: Identical electrical performance but limited to commercial temperature range (0°C to 70°C).

FAQ

How does the input common mode range behave near the negative rail?

The common mode range extends 100mV below ground. If inputs fall below this limit, internal substrate diodes may conduct, requiring external clamping for fast recovery.

What is the function of the internal hysteresis?

Internal hysteresis prevents output oscillation caused by noise or slow input transitions, eliminating the need for external feedback resistors in many applications.