AT&T Microelectronics has announced a V.32-compliant codec for modem developers, to encode and decode analogue telephone signals. The T7525 codec converts digital signals to analogue for telephone transmission and vice versa. It enables a developer to meet the V.32 standard of the Consultative Committee for International Telegraphy and Telephony, which specifies how modems communicate over the public switched telephone network at 9,600 bits-per-second, full-duplex. The T7525 has 12 bits of linear accuracy and is a high-precision, voiceband, sigma-delta pulse-code modulation codec with transmit and receive filters. The serial pulsecode modulation input-output uses a linear 16-bit two’s complement data format to support applications requiring 16 bits of dynamic range. In sigma-delta circuitry most of the conversion processing is done digitally, obviating the need for large areas of analogue circuitry and so minimising chip surface area and device cost. The codec can process 16-bit data, enabling it to interface directly with the AT&T DSP16A signal processor, without the need for additional circuitry. The transmit and receive digital filters can also be bypassed, to making echo-cancelling applications possible. Made in linear CMOS technology, the T7525 needs a 5-volt power supply. It is available in either a 24-pin plastic dual in-line package or a 28-pin plastic small-outline, J-lead package. In 24pin format it is $8.50 in quantities of 10,000.
