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NXP Semiconductors MC145481EG
- Part No.:
- MC145481EG
- Manufacturer:
- NXP Semiconductors
- Category:
- CODECS
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
MC145481EG.pdf
- Description:
- IC CODEC-FILTER PCM 3V 20-SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,577
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Product details
Overview
MC145481EG from Freescale Semiconductor is a single-supply, 20-pin PCM codec-filter IC performing voice digitization and reconstruction with pin-selectable μ-Law or A-Law companding. It integrates transmit band-pass (200 Hz–3.4 kHz) and receive low-pass (3.4 kHz) filters, on-chip 0.886 V precision reference, and fully differential analog signal path. It serves in telephony line interface circuits requiring 8 kHz sampling and 300 Ω push-pull power drivers.
For engineers reviewing the MC145481EG datasheet, MC145481EG pinout, MC145481EG application, or MC145481EG equivalent, this page delivers verified specifications, functional context for synchronous/asynchronous PCM timing modes (IDL/GCI/Long/Short Frame Sync), differential noise rejection architecture, and real-world telecommunication use cases - all grounded in Freescale's official technical data.
Technical Context
The MC145481EG implements a fully differential analog signal chain: TI+/TI− inputs feed an inverting op-amp (TG output), followed by active R-C pre-filtering, single-ended-to-differential conversion, and a 5-pole switched-capacitor band-pass filter (200 Hz–3.4 kHz) before the compressing A/D converter. All analog processing-including reference generation, CDAC/RDAC companding structure, and comparator-is differential to suppress supply noise and double input voltage swing.
Digital reconstruction uses a differential D/A converter, sinX/X-compensated 3.4 kHz switched-capacitor low-pass filter, active R-C post-filtering, and RO− output buffer. Power amplifiers (PO+/PO−) deliver ±1.772 V peak into 300 Ω with external gain control via PI, while PDI and FST/FSR dual-power-down modes reduce dissipation to 0.01 mW.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2.7 V to 5.25 V single supply - enables direct integration with 3 V or 3.3 V telephony systems without level-shifting. |
| Power Dissipation | 8 mW typical at 3 V; 0.01 mW in power-down - supports low-power line cards and battery-backed ISDN terminals. |
| Companding Law | PIN-selectable μ-Law (Pin 16 = VDD) or A-Law (Pin 16 = VSS) - eliminates firmware configuration and ensures regional compliance (North America/Japan vs. Europe). |
| Reference Voltage | 0.886 V internal precision reference - calibrated for −5 dBm TLP at 600 Ω, enabling accurate transmit/receive gain setting without external references. |
| Analog Bandwidth | Transmit: 200 Hz–3.4 kHz band-pass; Receive: 3.4 kHz low-pass - meets ITU-T G.711 spectral mask and eliminates need for external anti-aliasing/reconstruction filters. |
| Output Drive | PO+/PO− push-pull outputs drive 300 Ω load to ±1.772 V peak (3.544 VPP) - directly interfaces with telephone hybrid circuits and SLICs without external transformers. |
| Digital Interface | Supports Long Frame Sync, Short Frame Sync, IDL, and GCI timing - interoperates with MC145474/75 S/T transceivers and MC3419 SLICs in full U-interface designs. |
Pinout & Package
MC145481EG is housed in a 20-pin SSOP package (Case 940C), with lead pitch of 0.65 mm and body dimensions of 7.2 mm × 5.3 mm. Pin assignments are validated per Freescale's MC145481/D datasheet Rev 2 (11/98).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDD (6) | Positive power supply | Primary 2.7–5.25 V rail; requires 0.1 µF ceramic decoupling to VSS for stable analog operation. |
| VSS (15) | Negative power supply | Ground reference for digital logic and power supply return; not used as analog ground. |
| VAG (20) | Analog ground output | Mid-supply reference (VDD/2) for all analog circuitry; high-impedance in power-down mode. |
| Mu/A (16) | Companding law select | Logic-high = μ-Law; logic-low = A-Law - configures encoder/decoder behavior at boot, no runtime change. |
| PDI (10) | Power-down control | Active-low input; gates clocks and bias currents, placing RO−, PO+, PO−, DT, TG, and VAG in high-impedance state. |
| TI+ (19), TI− (18) | Transmit analog inputs | Fully differential op-amp inputs; support single-ended input referenced to VSS or VAG with minimal noise coupling. |
| TG (17) | Transmit gain output | Op-amp output feeding transmit filter; becomes high-Z when TI+ tied to VDD, enabling external signal injection. |
| RO− (2) | Receive analog output | Inverting output of smoothing filter; drives 2 kΩ load to 0.886 V peak referenced to VAG. |
| PI (3), PO− (4), PO+ (5) | Power amplifier interface | PI sets gain of push-pull PO+/PO− stage; PO+/PO− deliver differential 300 Ω drive; PI = VDD disables amplifiers. |
| FST (14), FSR (7) | Frame sync inputs | FST synchronizes DT output; FSR latches DR input; both low for >2 frames triggers auto-power-down. |
| BCLKT (12), BCLKR (9) | Bit clock inputs | BCLKT controls transmit data rate (64–4096 kHz); BCLKR = 1 selects IDL, = 0 selects GCI interface mode. |
| DT (13), DR (8) | Digital I/O | DT outputs 8-bit PCM under FST/BCLKT control; DR inputs PCM under FSR/BCLKR or FST/BCLKT depending on mode. |
Key Features
| Feature | Design Value |
|---|---|
| Fully differential analog design | Doubles effective input voltage swing and cancels common-mode supply noise, achieving >60 dB PSRR without external regulation. |
| On-chip precision reference | 0.886 V bandgap-derived reference enables −5 dBm TLP calibration at 600 Ω without external DAC or resistor networks. |
| Integrated active R-C filtering | Pre- and post-filtering stages eliminate out-of-band energy from switched-capacitor sections, removing need for external RC or LC filters. |
| Four digital interface modes | Hardware-selectable Long/Short Frame Sync, IDL, and GCI timing ensures drop-in compatibility with legacy Motorola telecom ASICs and SLICs. |
| Independent power amplifier control | PI pin allows standalone disable of PO+/PO− drivers without affecting codec functionality - critical for hybrid echo cancellation circuits. |
Applications
| ISDN S/T Interface Terminal | DSL Line Card Voice Channel |
|---|---|
Use Scenario: Integrating voice channel into ISDN basic rate (2B+D) terminal equipment compliant with ITU-T I.430. IC Role / Device Role / Timing Role: PCM codec-filter handling A-law companding, 8 kHz frame sync (FSR/FST), and 160 kbps BCLKR/BCLKT timing in GCI mode. Use Value: Eliminates discrete op-amps, filters, and reference ICs; enables single-chip voice interface matching MC145474/75 transceivers. | Use Scenario: Adding POTS voice backup channel to ADSL2+ line cards where space and power budget are constrained. IC Role / Device Role / Timing Role: Standalone μ-law codec operating in Long Frame Sync mode with shared 8 kHz FST/FSR and 256 kHz MCLK derived from DSL PHY clock. Use Value: Delivers 30 dB SNR over 40 dB dynamic range using on-chip differential filtering - meets GR-909 voice quality requirements without external components. |
| VoIP Gateway FXS Port | Industrial PBX Analog Trunk |
Use Scenario: Implementing FXS interface in embedded VoIP gateways requiring -48 V SLIC interfacing and local battery feed. IC Role / Device Role / Timing Role: Codec-filter providing RO−/PO+/PO− outputs to MC3419 SLIC, synchronized via IDL mode with BCLKR = 1 and FST = 8 kHz. Use Value: 300 Ω push-pull drive matches SLIC input impedance; VAG-referenced analog path minimizes crosstalk between voice and ringing detection circuits. | Use Scenario: Upgrading legacy PBX analog trunk cards to support digital switching while retaining existing analog line side hardware. IC Role / Device Role / Timing Role: A-law PCM interface bridging TDM backplane (DT/DR) to analog CO lines, using Short Frame Sync for deterministic latency. Use Value: Pin-selectable companding avoids firmware updates; power-down (PDI) enables per-port sleep during idle periods, cutting system standby power by 12 mW/port. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PCM codec-filter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC145503DW | Same 20-pin SOG package; lacks integrated power amplifiers (PO+/PO−); requires external op-amps for line driving. | Suitable only where external driver stage exists; cannot replace MC145481EG in SLIC-coupled designs without redesign. | Select when system already includes discrete 300 Ω drivers and board space is limited - avoids redundant amplification. |
| TP3067CP | 5 V-only supply (4.75–5.25 V); fixed μ-law only; no VAG/VAG Ref pins; different pinout (28-pin PDIP). | Requires level-shifting for 3 V systems; incompatible with A-law regions; needs PCB layout change due to package and pin count mismatch. | Choose only for legacy 5 V telephony designs where μ-law suffices and footprint change is acceptable. |
Compared with MC145481EG, MC145503DW removes integrated power drivers to reduce cost and die size but increases BOM count and layout complexity, while TP3067CP trades flexibility (single-supply, dual-law, VAG control) for maturity in older 5 V infrastructure - neither offers pin compatibility or identical feature set.
Availability
MC145481EG is available at Aetrix Electronics and suitable for ISDN terminal design, VoIP FXS port development, and industrial PBX analog trunk upgrades requiring stable component supply, long-lifecycle assurance, and traceable sourcing.
Supply support for MC145481EG 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 automotive, industrial, and networking solutions, with deep heritage in telecommunications ICs.
The MC145481EG belongs to Freescale's legacy telephony codec family, designed specifically for cost-sensitive, low-power voice channel interfaces in ISDN, DSL, and VoIP gateway applications - emphasizing integration, differential noise immunity, and multi-standard timing flexibility.
FAQ
What is the function of the VAG and VAG Ref pins on the MC145481EG?
The VAG pin (Pin 20) provides a mid-supply analog ground reference (VDD/2) for all internal analog circuitry, including the ADC, DAC, and filters. The VAG Ref pin (Pin 1) bypasses the on-chip VAG generator with a 0.1 µF capacitor to VSS. When audio signals are referenced to VSS, careful PCB layout is required to avoid noise coupling between VSS and VAG - the MC145481EG datasheet specifies short, low-inductance traces and separate analog/digital ground planes to maintain >60 dB PSRR. In power-down mode, VAG becomes high-impedance.
Can the MC145481EG operate with a 3.3 V supply, and what is its power consumption in active mode?
Yes, the MC145481EG operates across 2.7 V to 5.25 V, making 3.3 V fully supported. At 3 V supply, typical active power dissipation is 8 mW - measured with all functions enabled, 8 kHz frame sync, and continuous PCM traffic. This includes the codec, filters, reference, and power amplifiers. Power drops to 0.01 mW when PDI is asserted low or when FST and FSR are held low for >2 frames. No derating or external regulators are needed for 3.3 V operation.
How does the MC145481EG handle μ-Law versus A-Law companding selection?
The MC145481EG uses Pin 16 (Mu/A) for hardware-selectable companding: tying Mu/A to VDD selects μ-Law (used in North America and Japan), while tying it to VSS selects A-Law (standard in Europe). This selection configures both the encoder (ADC + compression) and decoder (expansion + DAC) simultaneously at power-up and remains fixed during operation. No software or register writes are involved - the choice is static and determined solely by the external logic level applied to Pin 16, ensuring deterministic behavior in telecom-certified systems.
What digital interface modes does the MC145481EG support, and how are they selected?
The MC145481EG supports four PCM timing modes: Long Frame Sync, Short Frame Sync, IDL, and GCI. Mode selection is controlled by BCLKR (Pin 9): logic high selects IDL mode (FST/BCLKT control both transmit and receive), logic low selects GCI mode. Long/Short Frame Sync is auto-detected based on FST pulse width relative to BCLKT edges - no pin configuration required. All modes use standard 8-bit serial PCM data at 8 kHz frame rate, ensuring interoperability with MC145474/75, MC145572, and other Motorola telecom ICs without protocol translation.
Does the MC145481EG include integrated filters, and what are their cutoff frequencies?
Yes, the MC145481EG integrates both transmit and receive filters on-die. The transmit path includes a 3-pole active R-C pre-filter followed by a 5-pole switched-capacitor band-pass filter with 200 Hz high-pass and 3.4 kHz low-pass characteristics. The receive path features a 5-pole switched-capacitor low-pass filter with sinX/X compensation at 3.4 kHz, followed by a 2-pole active R-C smoothing filter. These eliminate external filter components and ensure compliance with ITU-T G.711 spectral masks - no additional passive or active filtering is required for standard telephony bandwidth.
MC145481EG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Type:
- PCM, Filter
- Data Interface:
- PCM Audio Interface
- Resolution (Bits):
- 6 b
- Number of ADCs / DACs:
- 1 / 1
- Sigma Delta:
- No
- S/N Ratio, ADCs / DACs (db) Typ:
- -
- Dynamic Range, ADCs / DACs (db) Typ:
- -
- Voltage - Supply, Analog:
- -
- Voltage - Supply, Digital:
- 2.7V ~ 5.25V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
MC145481EG FAQ
1.How can I place an order for MC145481EG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC145481EG on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MC145481EG reliable?
The price and inventory of MC145481EG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC145481EG is usually 5 days.
3.What payment methods are accepted for MC145481EG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC145481EG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC145481EG?
MC145481EG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC145481EG order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MC145481EG?
For technical support, including MC145481EG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC145481EG requirements.
6.How does Aetrix verify that MC145481EG is sourced from the original manufacturer or authorized distributors?
All MC145481EG products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MC145481EG meets industry standards.
7.What is the process for return or replacement of MC145481EG?
All MC145481EG units undergo pre-shipment inspection (PSI). If there is an issue with MC145481EG, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MC145481EG part is unused and in its original packaging.
Return procedure for MC145481EG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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