LTC1042CN8#PBF

Overview

The LTC1042CN8#PBF is a monolithic CMOS window comparator manufactured using Linear Technology’s enhanced LTCMOS silicon gate process. It features two high-impedance voltage inputs, CENTER and WIDTH/2, which define the middle and width of the comparison window independently. The device provides TTL-compatible outputs: WITHIN WINDOW (high when input is inside the window), ABOVE WINDOW (high when input exceeds the upper limit), and BELOW WINDOW (high when input falls below the lower limit). It operates on a wide supply range from 2.8V to 16V with extremely low power consumption achieved through sampling techniques.

Feature Summary

• Uses sampled data techniques to achieve high accuracy and non-interacting control inputs for center and width adjustments.
• Provides independent ground-referred control inputs that allow common-mode operation to both supply rails.
• Features effectively chopper-stabilized performance ensuring high accuracy across temperature, power supply, and input voltage variations.
• Supports self-strobing via external RC networks or external strobing via CMOS gates for synchronized sampling.

Applications

• Fault detectors
• Go/No-Go testing
• Microprocessor power supply monitors

Procurement Notes

Verify the specific package type N8 (PDIP) against design requirements as the J8 package is listed as obsolete. Confirm RoHS compliance status and check for any recent product change notices regarding lead finish or material declarations before finalizing procurement plans.

Selection Notes

Select this component when ultralow power consumption is critical, as average power can be minimized by lowering the strobe rate. Ensure source resistance is managed; use bypass capacitors if source impedance exceeds 10kΩ to minimize charging current errors. Verify that the required sampling frequency aligns with the available timing resistor and capacitor values.

Part Context

This part belongs to the LTC1042 family of window comparators. It is distinct from general-purpose comparators due to its unique sampling architecture and micropower capabilities. The CN8 suffix indicates the commercial temperature range (-40°C to 85°C) and the PDIP-8 package format.

Replacement Considerations

Public confirmed substitute part numbers are not provided in the datasheet. Designers should evaluate other window comparators only if they can replicate the specific sampling-based low-power characteristics and input impedance behavior.

FAQ

How does the LTC1042 achieve such low power consumption?

It uses sampling techniques where power is applied to the comparators only during the active sampling cycle (approx. 80µs). Power is turned off between samples, allowing average power to be reduced arbitrarily by lowering the strobe rate.

What is the effect of source resistance on accuracy?

For source resistances greater than 10kΩ, the input capacitor cannot fully charge during the active time, causing voltage errors. Using an input bypass capacitor minimizes this error by sharing charge with the internal capacitor.