LTC1445CDHD#TRPBF

Overview

The LTC1445CDHD#TRPBF is an ultralow power quad comparator with a built-in reference, housed in a 16-lead plastic DFN package. It features a 1.221V ±1% internal reference and programmable hysteresis via the HYST pin. The device operates from a single 2V to 11V supply or dual ±1V to ±5.5V supply, drawing less than 8.5µA quiescent current. Outputs are TTL/CMOS compatible, sourcing up to 40mA. Input common mode range extends from V– to V+ – 1.3V. Propagation delay is typically 12µs at 10mV overdrive. The exposed pad connects internally to V–.

Feature Summary

• Built-in 1.221V reference output capable of driving bypass capacitors without oscillation
• Programmable hysteresis using external resistors connected to the HYST pin
• TTL/CMOS compatible outputs that source up to 40mA while maintaining microampere quiescent currents
• Elimination of cross-conducting crowbar current during logic state transitions

Applications

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

Procurement Notes

Verify the specific ordering suffix matches the required temperature grade and packaging format. The CDHD suffix indicates commercial temperature range (0°C to 70°C) and the DFN package. Confirm the TRPBF suffix denotes tape and reel delivery with lead-free finish. Cross-reference the part marking '1445' on the component body against official Linear Technology documentation to ensure authenticity and correct variant identification before integration into production designs.

Selection Notes

Select this component when low quiescent current is critical alongside the need for multiple comparator channels in a compact footprint. The LTC1445 is suitable for applications requiring programmable hysteresis and a stable internal reference voltage. Ensure the input signal amplitude and supply voltage range align with the specified common mode and operating limits. Consider the DFN package thermal characteristics if high ambient temperatures are expected within the commercial range.

Part Context

This device belongs to the LTC1443/LTC1444/LTC1445 family of ultralow power quad comparators. While sharing similar core architecture and pinouts, the LTC1445 differs from the LTC1443 by offering TTL/CMOS outputs instead of open-drain, and from the LTC1444 by providing sourced output current capability. All variants share the same low-power design philosophy and internal bandgap reference structure, differing primarily in output stage configuration and hysteresis control availability.

Replacement Considerations

Publicly confirmed substitute part numbers are not explicitly listed in the provided datasheet text. Designers should consult Analog Devices marketing for alternative components with compatible pinouts and electrical specifications if replacement is necessary.

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 voltage difference between REF and HYST is 50mV, resulting in a maximum hysteresis voltage band of 100mV.

What is the function of Pin 14 on the LTC1445?

Pin 14 is the HYST (Hysteresis) input. It allows for the connection of external resistors to program the hysteresis voltage band. If hysteresis is not required, this pin should be shorted to the REF pin.

Can the reference output drive large capacitive loads?

The reference output can drive a bypass capacitor of up to 0.01µF directly without oscillation. For larger capacitance values up to 100µF, a series damping resistor must be inserted between the REF pin and the capacitor.