LT1684CS#PBF

Telecom Overview

The LT1684CS#PBF is a micropower ring tone generator manufactured by Analog Devices Inc. It accepts a user-generated pulse width modulated (PWM) input and converts it to a high voltage sine wave suitable for telephone ringing applications. The device features an active tracking supply configuration that allows linear generation of the ring tone signal, eliminating the need for high voltage post-filtering. Key electrical parameters include a DC supply current of less than 1mA, a signal amplitude reference accuracy of 2%, and a differential input threshold of 0.5V to 1.0V. The output amplifier provides a short-circuit current capability of -190mA typical. The component operates within a junction temperature range of 0°C to 125°C for commercial grade parts.

Telecom Feature Summary

• Active Tracking Supply Configuration enables linear generation of the ring tone signal without requiring large high voltage filtering elements.
• Capacitive Isolation eliminates the need for optocouplers in the PWM input stage, providing robust noise immunity.
• Low Distortion Output meets international PTT requirements with harmonic suppression capabilities.
• User Adjustable Active Output Current Limit allows customization of drive capability via external resistors.

Telecom Applications

• Wireless Local Loop Telephones
• Key System/PBX Equipment
• Fiber to the Curb Telecom Equipment

Telecom Procurement Notes

Verify the specific suffix #PBF indicates lead-free compliance and RoHS status before procurement. Confirm the CS variant corresponds to the commercial temperature range (0°C to 125°C). Check for end-of-life notifications or discontinuance as this component may be obsolete. Ensure the ordering suffix matches the required package type, typically SOIC-14 for the IS/CS variants.

Telecom Selection Notes

Select the LT1684CS#PBF for commercial temperature applications requiring a micropower solution. Ensure the design supports the necessary external MOSFETs for the active tracking supply rails. Verify that the PWM controller can provide the required minimum differential input voltage of 1.6V. Consider the external filter component values needed to achieve the desired ring frequency and carrier rejection characteristics.

Telecom Part Context

The LT1684 series serves as a specialized telecommunication ring tone generator designed to replace traditional electromechanical ringer systems. It integrates an isolated PWM DAC, active filter, and driver into a single IC. The CS designation denotes the commercial temperature grade version of the device, distinct from the IN industrial grade variant. This part is part of the broader LT1684 family focused on telecom signaling.

Telecom Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation. The datasheet does not list direct replacements. Designers should verify if the LT1684IN#PBF (Industrial Grade) is compatible if temperature range adjustments are needed, though this is a grade variation rather than a functional replacement.