LTC1445CN#PBF

Overview

The LTC1445CN#PBF is an ultralow power quad comparator with a built-in 1.221V ±1% reference, housed in a 16-lead PDIP package for commercial temperature operation (0°C to 70°C). It features programmable hysteresis via the HYST pin and TTL/CMOS compatible outputs capable of sourcing up to 40mA. The device operates from a single 2V to 11V supply or dual ±1V to ±5.5V supplies, drawing a maximum of 8.5µA quiescent current. Propagation delay is typically 12µs with 10mV overdrive.

Feature Summary

• Built-in precision voltage reference outputting 1.221V with ±1% accuracy
• Programmable hysteresis functionality using external resistors connected to the HYST pin
• TTL/CMOS compatible push-pull output stage capable of sourcing significant current
• Elimination of crowbar current during logic state transitions to prevent supply glitches

Applications

• Battery-powered system monitoring
• Threshold detectors
• Window comparators
• Oscillator circuits

Procurement Notes

Verify the specific suffix CN#PBF confirms the commercial temperature range and lead-free finish. Ensure the 16-lead PDIP package matches the target PCB footprint. Confirm the part number corresponds to the LTC1445 variant with the 1.221V reference and programmable hysteresis, distinct from the LTC1443 or LTC1444 models which have different reference voltages or output configurations.

Selection Notes

Select this component when a quad comparator with integrated reference and programmable hysteresis is required in a through-hole package. The LTC1445 offers TTL/CMOS outputs suitable for digital interfacing, unlike the open-drain LTC1444. Verify that the 1.221V reference voltage aligns with the application's threshold requirements and that the 8.5µA supply current meets the low-power design constraints.

Part Context

This part belongs to the LTC1443/LTC1444/LTC1445 family of ultralow power quad comparators. While sharing similar architecture and pinouts, the LTC1445 is distinguished by its 1.221V internal reference and TTL/CMOS output stage. It serves as a low-power alternative to higher-current comparators, designed for battery-operated devices where minimizing quiescent current is critical while maintaining precise voltage detection capabilities.

Replacement Considerations

The LTC1444CS#PBF is a pin-compatible upgrade but features an open-drain output instead of TTL/CMOS. The LTC1443CN#PBF shares the same package and temperature grade but has a 1.182V reference and separate ground pin configuration. Direct substitution requires verifying output drive requirements and reference voltage compatibility.

FAQ

How is hysteresis programmed on the LTC1445?

Hysteresis is set by connecting two resistors between the REF and HYST pins and from HYST to V–. The maximum hysteresis voltage band is 100mV, determined by keeping the voltage difference between REF and HYST within 50mV.

What is the input common mode voltage range?

Each comparator’s input operates from the negative supply (V–) to within 1.3V of the positive supply (V+).

Can the reference output drive large capacitors?

The reference can drive a bypass capacitor of up to 0.01µF directly without oscillation. For larger capacitance values, a series damping resistor must be inserted between the REF pin and the capacitor.