DESCRIPTION

· The N681386/87 is a single-channel FXS telephone line interface optimized for short loop applications.
· It integrates SLCC functionality with a programmable CODEC and a DC/DC controller.
· Supports internal ringing up to 90 V PK (5 REN at 4k ft) for CPE.
· CODEC configurable for μ-law, A-law, or 16-bit linear PCM encoding.
· Includes tone generation, ring tones, DTMF detection/generation, and FSK generation.
· Features an on-chip PWM driver for inductor-based DC/DC converter control.
· Programmable impedance and trans-hybrid balancing for global deployment.

FEATURES

· Complete BORSCHT functions.
· Internal balanced and unbalanced ringing up to 90 VPK (5 REN up to 4k ft).
· Integrated Power Management with DC/DC controller and programmable external battery switching.
· Programmable linefeed characteristics including ringing frequency, amplitude, and cadence.
· Supports trapezoidal and sinusoidal waveforms, two-wire AC impedance, and trans-hybrid balance.
· Constant Current feed (20 to 41 mA), Ring Trip, Loop Closure Thresholds, and Ground Key Detection.
· Programmable signal generation and detection including DTMF and FSK Enhanced Caller ID.
· Loop test and diagnostics support with integrated loopback modes, real-time linefeed monitoring, and on-chip temperature sensor.
· Digital interfaces: PCM (G.711 μ-Law, A-Law, 16-bit linear), GCI, SPI bus, and programmable audio path gains.
· Supports both PCM Master and Slave modes with on-chip PLL for flexible clocking options.
· Operating voltage: 3.3V.
· Available in Narrowband Codec (N681386) and Wideband & Narrowband codec (N681387).
· Optional integrated (N681622) or discrete Subscriber Line Feed Circuit.

APPLICATIONS

· Residential VoIP Gateways / Routers / IP-PBX.
· Fiber to the Premise/Home (FTTP/H).
· Wireless Local Loop.
· Optical Network Terminals (ONT).
· Analog Telephone Adapter (ATA).
· Voice-enabled DSL/Cable Modems.
· Integrated Access Devices.
· Set Top Boxes.