The Le79252 Dual Intelligent Subscriber Line Interface Circuit (ISLIC) device, in combination with an Le79228x ISLAC device, implements the telephone line interface function. This enables the design of a low cost, high performance, fully software programmable line interface for multiple country applications worldwide. All AC, DC, and signaling parameters are fully programmable via microprocessor or GCI interfaces on the Le79228x ISLAC devices. Additionally, the Le79252 device has integrated self-test and line-test capabilities to resolve faults to the line or line circuit. The integrated test capability is crucial for remote applications where dedicated test hardware is not cost effective. When combined with Microchip's Le79114 VCP II device, an optimized chip set with additional performance features can be realized.

• Monitor of two-wire interface voltages and currents supports
• Voice transmission
• Internal ringing generation
• Programmable DC feed characteristics
• Selectable off-hook and ground-key thresholds
• Subscriber line diagnostics
• Foreign voltage sensing
• Power cross and fault detection
• Supports 85 Vrms internal ringing
• 3.3 V and battery supplies
• Dual battery operation for system power saving
• Automatic battery switching
• Intelligent thermal management
• Compatible with inexpensive protection networks
• Accommodates low tolerance fuse resistors or PTC thermistors
• Metering capable
• 12 kHz and 16 kHz
• Smooth polarity reversal
• Tip-open state supports ground start signaling
• Integrated test load switch/relay drivers
• 5 REN with DC offset