The MX609 is a Continuously Variable Slope Delta Modulation (CVSD) Codec designed for use in cordless telephones. The device is suitable for applications in delta multiplexers, switches and phones. Encoder input and decoder output switched capacitor filters are incorporated on-chip. Sampling clock rates can be programmed to 16, 32 or 64K bits/second from an internal clock generator or externally injected in the 8 to 64K bits/second range. The internal clocks are derived from an on-chip reference oscillator driven by an externally connected crystal. The sampling clock frequency is output for the synchronization of external circuits. The encoder has an enable function for use in multiplexer applications. When not enabled the encoder output remains in a high-impedance "tri-state" mode. Companding circuits may be operated with an externally selectable 3- or 4-bit algorithm. The device may be put in standby mode when Powersave is selected. The MX609 operates with a supply voltage of 5.0V and is available in the following packages: 24-pin PLCC (MX609LH), 16-pin SOIC (MX609DW), 22-pin CERDIP (MX609J), and 22-pin PDIP (MX609P).