LE79555-2FQC

Telecom Overview

The LE79555-2FQC is a Subscriber Line Interface Circuit (SLIC) from the Zarlink VoiceEdge VE580 series, manufactured by Microchip Technology. It operates in a 32-pin QFN package with an exposed thermal pad and supports -40 to -58 V battery operation. The device features an internal switching regulator for power efficiency and provides six control states: Active, Reverse Polarity, Tip Open, Ringing, Standby, and Open Circuit. Key electrical specifications include a longitudinal capability of 63 dB, C-message weighted noise of +10 dBrnC at 0°C to +70°C, and a receive summing node impedance of 10 to 20 Ω. It supports 30 mA feed current and includes on-chip relay drivers.

Telecom Feature Summary

• Integrated on-chip switching regulator minimizes system power dissipation and eliminates the need for a secondary voltage supply.
• Supports ground-start lines with automatic ring-ground fault detection and tip open state functionality.
• Includes three on-chip relay drivers with snubbers, one dedicated for ringing and two general-purpose outputs.
• Provides programmable constant-current feed and loop-detect thresholds for flexible line card design.

Telecom Applications

• High-density POTS linecard applications
• Low-power subscriber line interface circuits
• Telecommunications equipment requiring small footprint solutions

Telecom Procurement Notes

Verify the specific ordering suffix 'T' if tape and reel packaging is required instead of standard tray packing. Confirm that the 32-pin QFN package with exposed pad matches the target PCB layout requirements. Ensure compatibility with the intended SLAC devices for complete line circuit optimization.

Telecom Selection Notes

Select this component for designs prioritizing power savings and board space reduction due to its integrated switching regulator and compact QFN package. Consider the 63 dB longitudinal capability and low noise specifications for high-quality voice transmission. Verify that the operating temperature range meets the environmental requirements of the deployment location.

Telecom Part Context

The LE79555-2FQC belongs to the Zarlink VoiceEdge VE580 series of SLIC devices. It is designed as a cost-effective alternative to transformer-based SLICs, offering similar performance with reduced size and power consumption. The device is compatible with various SLAC devices from the same family to form a complete line circuit solution.

Telecom Replacement Considerations

The LE79555-2BVC is a pin-compatible alternative in a 44-pin TQFP package. Designers must account for the difference in package size and pin count when substituting between the QFN and TQFP variants.