NXP Semiconductors MC145483DT

Overview

MC145483DT from Freescale Semiconductor is a 13-bit linear PCM codec-filter IC performing voice digitization and reconstruction with on-chip transmit band-pass (200 Hz–3.4 kHz) and receive low-pass (3.4 kHz) filtering, 2's complement data format, and single 3 V supply operation. It integrates differential switched-capacitor filters, active R-C pre/post-filtering, and an on-chip 0.886 V precision reference for –5 dBm TLP at 600 Ω, targeting telephony analog front-ends.

For engineers reviewing the MC145483DT datasheet, MC145483DT pinout, MC145483DT application, or MC145483DT equivalent, key selection criteria include its TSSOP-20 package, synchronous/asynchronous clock support (FST/FSR up to 8 kHz), differential analog architecture for >75 dB dynamic range, and configurable receive gain control (0 to –21 dB in 3 dB steps).

Technical Context

The MC145483DT implements a fully differential analog signal path: input op amp (TI+/TI–) feeds a differential R-C pre-filter, then a 5-pole switched-capacitor anti-aliasing LPF (3.4 kHz), followed by a 3-pole HPF (200 Hz cutoff) bypassable via HB pin. All ADC/DAC conversion occurs differentially using shared 13-bit CDAC/RDAC architecture referenced to auto-zeroed bandgap voltage.

Digital interface supports Long/Short Frame Sync modes, with BCLKT/BCLKR configurable for 256–4096 kHz bit clocks; MCLK accepts 256 kHz–4.096 MHz and auto-scales internal 256 kHz sequencing clock. Receive gain adjustment mode adds 3-bit attenuation control via DR pin, while PDI enables 0.01 mW power-down with high-impedance outputs (DT, RO–, PO±, TG, VAG).

Key Specifications

Pinout & Package

MC145483DT is housed in a 20-pin Thin Shrink Small Outline Package (TSSOP), case 948E, with 0.65 mm pitch and exposed pad for thermal management. Pin assignments match SOG and SSOP variants per Freescale datasheet rev 3 (2003).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PCM codec applications.

Compared with TLV320AIC10IPFB and CS44600-CQZ, the MC145483DT offers integrated telephony-optimized filtering, differential analog design for noise immunity, and true single-chip 13-bit PCM codec functionality - making it uniquely suited for cost-sensitive, space-constrained voice infrastructure requiring G.711 compliance.

Availability

MC145483DT is available at Aetrix Electronics and suitable for VoIP gateways, digital PBX line cards, and wireless handset baseband designs requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.

Supply support for MC145483DT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Freescale Semiconductor (now part of NXP Semiconductors) is a fabless semiconductor company specializing in embedded processing, analog, and mixed-signal solutions for automotive, industrial, and communications markets.

The MC145483DT belongs to Freescale's legacy telephony codec product line, designed specifically for G.711-compliant voice digitization in cost-sensitive, low-power digital communication systems such as PBX, VoIP, and wireless handsets.

FAQ

What is the function of the HB pin on the MC145483DT?

The HB (High-Pass Filter Bypass) pin on the MC145483DT controls whether the on-chip 200 Hz third-order high-pass filter is enabled or bypassed. A logic low activates the filter to attenuate 50/60 Hz power-line interference; a logic high removes it from the signal path, allowing DC-coupled operation. This feature ensures compatibility with both AC-coupled telephone lines and DC-coupled microphone or sensor interfaces in the MC145483DT.

Does the MC145483DT support both synchronous and asynchronous clocking modes?

Yes, the MC145483DT supports both synchronous and asynchronous operation. FSR and FST can be clocked independently (asynchronous mode) or aligned (synchronous mode), and BCLKR can serve as either a receive bit clock or a mode-select pin. The MC145483DT's internal prescaler automatically adapts to MCLK frequencies from 256 kHz to 4.096 MHz, enabling flexible integration with diverse timing sources without external PLLs or dividers.

What is the purpose of the VAG and VAG Ref pins on the MC145483DT?

The VAG pin provides a mid-supply (1.5 V) analog ground reference for all internal analog circuitry, while VAG Ref is its dedicated bypass node. A 0.1 µF capacitor must connect VAG Ref to VSS to stabilize the on-chip bandgap reference; VAG itself requires a 0.01 µF capacitor to VSS to suppress clock feedthrough. In the MC145483DT, this dual-node design isolates sensitive analog ground from digital noise, enabling high PSRR and <1 LSB idle-channel noise performance.

Can the MC145483DT drive a 600 Ω telephone line directly?

No, the MC145483DT's PO+/PO– outputs are optimized for 300 Ω differential loads and cannot directly drive legacy 600 Ω balanced telephone lines. Its 3.544 Vpp output into 300 Ω corresponds to –5 dBm at 600 Ω only under matched conditions. For 600 Ω line driving, an external transformer or line driver IC (e.g., SLIC) is required. The MC145483DT is intended as an analog front-end, not a line interface device.

How does the MC145483DT achieve its 0.01 mW power-down state?

The MC145483DT achieves 0.01 mW power-down by gating all internal clocks and disabling bias currents when PDI is pulled low or when both FST and FSR are held low for several frames. In this state, DT, RO–, PO+, PO–, TG, and VAG go high-impedance, and VAG Ref is pulled to VDD. Recovery requires PDI high and valid FST pulses; DT remains high-Z for ≥2 FST cycles to allow VAG and filter settling - ensuring clean power-up behavior in the MC145483DT.