The Si32260/1 Dual ProSLIC® devices, in a single package, implement two complete foreign exchange station (FXS) telephony interfaces. The Si32260/1 devices operate from a 3.3 V supply and have standard PCM/SPI or GCI (8x8 mm package only) bus digital interfaces. A pair of built-in dc-dc converter controllers can be used to automatically generate the optimal battery voltage required for each line-state, optimizing efficiency and minimizing heat generation. The Si32260/1 devices are designed to operate not only with a tracking battery supply for each channel for lowest power consumption, but also with shared battery supplies, for lowest cost. When used with shared battery supplies, the internal dc-dc controller operates in Tracking Shared Supply (TSS) mode to deliver power consumption lower than typical fixed voltage shared rail designs (shared supplies are not currently supported by the 6 x 8 mm package option). Self-testing and metallic loop testing (MLT) (e.g., GR-909) is facilitated by the built-in DSP, monitor ADC, and test load. The devices are available with linefeed voltage ratings of –110 V (Si32260) or –140 V (Si32261) to support high voltage ringing, and both devices support wideband audio for better-than-PSTN voice quality. The Si32260/1 devices are available in a 6 x 8 mm 47-pin QFN package or an 8 x 8 mm 60-pin QFN package.