MC145554DW

Product Summary

The MC145554DW is a PCM Codec–Filter. The MC145554DW performs the voice digitization and recon-struction as well as the band limiting and smoothing required for PCM sys-tems. The MC145554DW is designed to operate in both synchronous and asynchronousapplications and contain an on–chip precision voltage reference. The MC145554DW has an input operational amplifier whose output is the inputto the encoder section. The encoder section immediately low–pass filter the analog signal with an active R–C filter to eliminate very–high–frequency noisefrom being modulated down to the pass band by the switched capacitor filter.From the active R–C filter, the analog signal is converted to a differential sig-nal. From this point, all analog signal processing is done differentially. This allows processing of an analog signal that is twice the amplitude allowed by asingle-ended design, which reduces the significance of noise to both the invert-ed and non–inverted signal paths. Another advantage of this differential designis that noise injected via the power supplies is a common–mode signal that iscancelled when the inverted and non–inverted signals are recombined. This dramatically improves the power supply rejection ratio.

Parametrics

MC145554DW absolute maximum ratings: (1)DC Supply Voltage-VCC to VBB: -0.5 to + 13V; (2)DC Supply Voltage-VCC to GNDA: -0.3 to + 7.0V; (3)DC Supply Voltage-VBB to GNDA: -7.0 to + 0.3V; (4)Voltage on Any Analog Input or Output Pin: VBB–0.3 to VCC+0.3V; (5)Voltage on Any Digital Input or Output Pin: GNDA–0.3 to VCC+0.3V; (6)Operating Temperature Range: – 40 to + 85℃; (7)Storage Temperature Range: – 85 to + 150℃.

Features

MC145554DW features: (1)Fully Differential Analog Circuit Design for Lowest Noise; (2)Performance Specified for Extended Temperature Range of–40 to + 85℃; (3)Transmit Band–Pass and Receive Low–Pass Filters On–Chip; (4)Active R–C Pre–Filtering and Post–Filtering; (5)On–Chip Precision Voltage Reference (2.5 V); (6)Typical Power Dissipation of 40 mW, Power Down of 1.0 mW at ±5 V.

Diagrams