The MX629 is a Continuously Variable Slope Delta Modulation (CVSD) Codec designed for use in military communications systems. This device is suitable for applications in military delta multiplexers, switches, and phones. The MX629 is designed to meet Mil-Std-188-113 specifications. Encoder input and decoder output filters are incorporated on-chip. Sampling clock rates can be programmed to 16, 32, or 64kbps from an internal clock generator or externally injected in the 8 to 64kbps range. The sampling clock frequency is output for the synchronization of external circuits. The encoder has an enable function for use in multiplexer applications. Encoder and Decoder forced idle capabilities are provided forcing 10101010...pattern in encode and a VDD/2 bias in decode. The companding circuit may be operated with an externally selectable 3- or 4-bit algorithm. The device may be placed in standby mode by selecting Powersave. A reference 1.024MHz oscillator uses an external clock or crystal. The MX629 operates with a supply voltage of 5.0V and is available in the following packages: 24-pin PLCC (MX629LH), 22-pin CERDIP (MX629J), and 22-pin PDIP (MX629P).