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Microchip Technology U4082B-MFLG
- Part No.:
- U4082B-MFLG
- Manufacturer:
- Microchip Technology
- Category:
- Telecom
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
U4082B-MFLG.pdf
- Description:
- IC TELECOM INTERFACE 28SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,796
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Product details
Overview
U4082B-MFLG from Microsemi (now Microchip) is a low-voltage, voice-switched speakerphone IC designed for hands-free telephony systems. It integrates transmit/receive attenuators with 52 dB gain range, four-point signal sensing, background noise monitoring, dial tone detection, and on-board filter circuitry. It operates from 3V to 6.5V and supports line-powered or standalone operation via Tip/Ring coupling - ideal for cordless phone base stations and VoIP speakerphones.
For engineers reviewing the U4082B-MFLG datasheet, U4082B-MFLG pinout, U4082B-MFLG application, or U4082B-MFLG equivalent, key selection considerations include its half-duplex switching logic, hybrid amplifier interface capability, CT-controlled mode timing, VB-biased analog architecture, and compatibility with U4083B speaker amplifier in full system design.
Technical Context
The U4082B-MFLG implements a dual-path, level-detector-driven voice switch using two independent receive/transmit detector pairs (RLI1/RLO1 & RLI2/RLO2; TLI1/TLO1 & TLI2/TLO2), each feeding comparators that drive an attenuator control block. Its CT pin (14) voltage relative to VB directly encodes operating mode: +240 mV = receive, –240 mV = transmit, 0 V = idle.
Background noise rejection is achieved via two dedicated monitors (CPR/CPT pins) using slow-charge/fast-decay RC time constants (~4.7 s), while AGC reduces receive gain by up to 25 dB below 3.5 V supply to maintain stability on long telephone lines. The microphone amplifier features all-NPN output stage for reactive-load stability and >1 MHz gain-bandwidth.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 3.0 V to 6.5 V - enables direct line-power operation (5.5 mA typical) or battery-powered designs without external regulators. |
| Transmit/Receive Attenuation Range | 52 dB - ensures loop gain remains <1 across acoustic and electrical paths, preventing oscillation in speakerphone configurations. |
| CT Control Voltage Swing | ±240 mV vs VB - provides precise, rail-independent mode control; allows external RC tuning of fast idle (30 ms) and slow idle (1 s) transitions. |
| VB Output | ≈ VS/2 (e.g., 2.4 V at VS = 5.0 V) - serves as system AC ground and bias reference for all amplifiers and level detectors. |
| Dial Tone Detection Threshold | 10–20 mVrms at RI pin - prevents false idle entry during dial tone reception, maintaining full receive gain until speech begins. |
| Microphone Amp Gain Bandwidth | 1.0 MHz - supports wideband audio fidelity and stable operation into capacitive loads (e.g., transformer-coupled mics). |
| Hybrid Amplifier Output Swing | Typ. 1.2 Vpp below VS - delivers sufficient headroom for 2-wire to 4-wire conversion with standard telephone line transformers. |
Pinout & Package
U4082B-MFLG is housed in a 28-pin SOIC (SO28) package with 0.3-inch body width and standard JEDEC MS-012AC footprint. Pin 28 is GND; pin 4 is VS; pin 15 is VB (system AC ground); pin 14 is CT (attenuator control); pins 5/6 are differential HTO+ and HTO– outputs for hybrid transformer interface.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 (FO) | Filter output | Low-impedance buffer (<50 Ω) driving external high-pass/low-pass/band-pass networks to suppress 60 Hz hum or prevent acoustic feedback. |
| 3 (CD) | Chip disable | Logic input: low = active, high = power-down - disables mic/hybrid amps and level detectors while preserving filter/attenuator bias. |
| 9 (TI) / 21 (RI) | Attenuator inputs | 10 kΩ input impedance; max 350 mVrms signal - accepts mic/speaker and line-side signals for real-time level comparison. |
| 13 (VCI) | Volume control input | Voltage referenced to VB (0.3×VB to VB) - adjusts receive gain only, enabling user volume control without affecting transmit path or idle behavior. |
| 14 (CT) | Attenuator control | Analog control node: ±240 mV vs VB sets transmit/receive mode; internal current sources and 2 kΩ fast-discharge path enable precise timing control. |
| 17–20, 23–26 | Level detector I/O | Four dedicated pairs (TLI1/TLO1, TLI2/TLO2, RLI1/RLO1, RLI2/RLO2) - enable independent sensitivity tuning per path using external RC networks. |
Key Features
| Feature | Design Value |
|---|---|
| Four-point signal sensing | Independent level detection on both line-side (TLI1/RLI1) and speaker/mic-side (TLI2/RLI2) paths - eliminates false triggering from echo or near-end noise. |
| Background noise monitoring | Dual RC-based monitors (CPR/CPT) with ~4.7 s time constant - distinguishes speech bursts from steady-state room/line noise, improving talker detection reliability. |
| AGC for low-voltage operation | Reduces receive gain up to 25 dB when VS < 3.5 V - maintains stable speaker output and prevents supply sag on long telephone lines. |
| Dial tone detector | 15 mV threshold comparator referenced to VB - holds receive path active during dial tone, avoiding premature fade to idle mode. |
| Hybrid amplifier interface | Differential HTO+/HTO– outputs with –1 fixed gain stage - simplifies 2-wire to 4-wire conversion using off-the-shelf coupling transformers. |
Applications
| Cordless Phone Base Station | VoIP Speakerphone Terminal |
|---|---|
Use Scenario: Full-duplex conversation over PSTN or SIP trunk with hands-free operation in home/office environments. IC Role / Device Role / Timing Role: Voice-switched attenuator controller managing half-duplex path selection, hybrid interface, and background noise-adaptive gain control. Use Value: Prevents acoustic howl and line echo via 52 dB attenuation range and fast (30 ms) mode switching, while maintaining intelligibility in ambient noise up to 65 dB SPL. |
Use Scenario: USB or Ethernet-connected speakerphone supporting remote conferencing with local mic/speaker and network audio streaming. IC Role / Device Role / Timing Role: Analog front-end voice switch coordinating mic preamp, line-level receive path, and hybrid-coupled transmit path under software-defined CT control. Use Value: Enables seamless integration with U4083B speaker amplifier and digital codec; VB-referenced architecture simplifies single-supply mixed-signal board layout. |
| Hotel/Multi-line Telephone System | Emergency Intercom Unit |
Use Scenario: Shared speakerphone unit serving multiple room lines with automatic line seizure and talker priority arbitration. IC Role / Device Role / Timing Role: Centralized voice activity detector and path attenuator with dial tone hold and fast idle resolution for multi-talker contention. Use Value: Four-level detector architecture resolves simultaneous talker conflicts (fast idle) and recovers rapidly (30 ms) when one speaker dominates - critical for multi-line call handover. |
Use Scenario: Ruggedized wall-mounted intercom for fire command centers or industrial facilities requiring reliable hands-free communication amid machinery noise. IC Role / Device Role / Timing Role: Noise-immune voice switch with background monitor and adjustable mic gain - operates from 3 V battery or PoE-derived supply. Use Value: CPR/CPT-based noise tracking maintains talker detection accuracy in broadband noise >80 dB(A); low 2.8 V minimum operation extends battery life in backup mode. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voice-switched speakerphone applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SLAB001A (Silicon Labs) | Digital voice switch with integrated ADC/DAC and I²C control; no analog CT/VB architecture; requires external µC for mode management. | Targets modern VoIP platforms needing firmware-upgradable features; lacks native hybrid amplifier outputs and line-power capability. | Select SLAB001A only when digital control, audio processing, or firmware configurability outweighs analog simplicity and line-power operation. |
| TP3067 (Texas Instruments) | Single-chip PCM codec with built-in speakerphone algorithm; fixed 64 kbps TDM interface; no discrete level detector pins or VB reference. | Suitable for T1/E1 channel banks or digital PBX systems; not designed for analog Tip/Ring interfacing or transformer-coupled hybrids. | Choose TP3067 for time-division multiplexed telephony infrastructure; avoid for analog standalone speakerphone designs requiring CT timing or hybrid amp outputs. |
Compared with SLAB001A and TP3067, U4082B-MFLG offers direct analog control of half-duplex switching via CT voltage, native hybrid amplifier outputs, and true line-powered operation - making it uniquely suited for cost-sensitive, analog-centric speakerphone hardware without embedded processor dependency.
Availability
U4082B-MFLG is available at Aetrix Electronics and suitable for cordless phone base stations, VoIP speakerphone terminals, hotel multi-line systems, emergency intercom units, and analog telephony interface modules requiring stable component supply and long-lifecycle support.
Supply support for U4082B-MFLG 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
Microsemi (acquired by Microchip Technology in 2018) specialized in high-reliability analog and mixed-signal ICs for communications, aerospace, and industrial applications.
The U4082B-MFLG belongs to Microsemi's legacy telephony analog front-end product line, engineered specifically for robust, low-power, transformer-coupled speakerphone systems operating directly from telephone line power or minimal DC supplies.
FAQ
What is the minimum supply voltage required for functional operation of the U4082B-MFLG?
The U4082B-MFLG operates down to 2.8 V, though recommended conditions specify 3.5 V minimum for full performance. At 2.8 V, AGC reduces receive gain by up to 25 dB to maintain stability; supply current remains ~5.5 mA. Below 2.8 V, functionality degrades progressively, and the device may fail to enter transmit mode reliably. Always verify VB output and CT swing under actual low-VS conditions in U4082B-MFLG designs.
How does the U4082B-MFLG handle simultaneous speech from both parties?
The U4082B-MFLG enters "Fast Idle" mode when level detectors disagree - e.g., strong signal at TLI2 but also strong signal at RLI1 - indicating bidirectional speech. This triggers rapid (30 ms) attenuation of both paths to break the acoustic loop. Fast Idle persists until one side dominates by ≥4 dB (set by 36 mV comparator offset), after which normal transmit or receive mode resumes. This behavior is intrinsic to U4082B-MFLG's dual-comparator control architecture.
Can the U4082B-MFLG be used without a coupling transformer?
Yes - the U4082B-MFLG supports transformerless operation via handset speech network interface (as shown in Figure 1-2), using HTI/HTO+ and HTO– pins with external resistive feedback. However, transformer coupling is strongly recommended for PSTN line isolation, common-mode noise rejection, and impedance matching. Transformerless use is limited to isolated, low-noise internal audio buses and requires careful PCB layout to avoid ground loops in U4082B-MFLG implementations.
What is the role of the VB pin in U4082B-MFLG system design?
VB (pin 15) is a buffered mid-supply reference ≈VS/2, serving as AC ground and bias point for all internal amplifiers, level detectors, and attenuators. Its 400 Ω output impedance and requirement for external decoupling (typically 2–10 µF) make it critical for PSRR - achieving 54 dB rejection at 1 kHz. All signal references (e.g., CT, VCI, MUTE) are defined relative to VB, so improper VB decoupling directly degrades U4082B-MFLG switching accuracy and noise immunity.
Is the U4082B-MFLG pin-compatible with earlier U4082 variants like U4082A?
No - U4082B-MFLG is not pin-compatible with U4082A. While both are 28-pin SOIC voice-switched ICs, U4082B introduces revised level detector thresholds, updated AGC behavior below 3.5 V, and modified CT drive characteristics. Pin functions differ at TLI1/TLI2, RLI1/RLI2, and CPR/CPT locations. Migration from U4082A to U4082B-MFLG requires schematic and layout revision; consult Rev. 4743D datasheet for full U4082B-MFLG pin mapping and validation.
U4082B-MFLG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Voice-Switched Speakerphone
- Interface:
- -
- Number of Circuits:
- 1
- Voltage - Supply:
- 3.5V ~ 6.5V
- Current - Supply:
- 5.5mA
- Power (Watts):
- 520 W
- Operating Temperature:
- -20°C ~ 60°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SO
U4082B-MFLG FAQ
1.How can I place an order for U4082B-MFLG through Aetrix?
Please submit a Request for Quotation (RFQ) for U4082B-MFLG 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 U4082B-MFLG reliable?
The price and inventory of U4082B-MFLG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for U4082B-MFLG is usually 5 days.
3.What payment methods are accepted for U4082B-MFLG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for U4082B-MFLG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for U4082B-MFLG?
U4082B-MFLG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your U4082B-MFLG 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 U4082B-MFLG?
For technical support, including U4082B-MFLG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your U4082B-MFLG requirements.
6.How does Aetrix verify that U4082B-MFLG is sourced from the original manufacturer or authorized distributors?
All U4082B-MFLG 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 U4082B-MFLG meets industry standards.
7.What is the process for return or replacement of U4082B-MFLG?
All U4082B-MFLG units undergo pre-shipment inspection (PSI). If there is an issue with U4082B-MFLG, 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 U4082B-MFLG part is unused and in its original packaging.
Return procedure for U4082B-MFLG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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