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Microchip Technology U4037B-NFLG3Y
- Part No.:
- U4037B-NFLG3Y
- Manufacturer:
- Microchip Technology
- Category:
- Telecom
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
U4037B-NFLG3Y.pdf
- Description:
- IC TELECOM INTERFACE 24SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,175
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Product details
Overview
U4037B-NFLG3Y from Atmel (now Microchip) is a line-powered, microcontroller-controlled telephone circuit IC for analog subscriber line interface in wired telephone sets. It integrates speech circuitry, tone-ringer interface, sidetone equivalent, ear-protection rectifiers, and DTMF handling - delivering 48 dB transmit gain, 12 dB receive gain, ±0.5 dB frequency response flatness (300–3400 Hz), and operation from as low as 8 mA line current.
For engineers reviewing the U4037B-NFLG3Y datasheet, U4037B-NFLG3Y pinout, U4037B-NFLG3Y application, or U4037B-NFLG3Y equivalent, key selection considerations include line-current-dependent gain control (AGA pin), symmetrical microphone/receiver amplifier topology, built-in anti-clipping and ear protection, and SO24-packaged integration of all core analog telephony functions without external transformers.
Technical Context
The U4037B-NFLG3Y implements a fully integrated analog front-end for POTS telephone sets, with independent transmit and receive amplification paths, programmable sidetone suppression via ST pin, and automatic line-loss compensation controlled by AGA resistor value. Its dual differential outputs (RECO1/RECO2, OUT1/OUT2) support balanced earpiece and ringer drive.
It features a dedicated DTMF amplifier path (41.7 dB typical gain), MUTE input for microphone disabling during dialing, and power-down mode (PD pin) that shorts VL and reduces quiescent current. All functional blocks - including VMP-regulated 3.4 V supply (4 mA capable) - are powered directly from the telephone line.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Transmit Gain | 48 dB typical - enables sufficient signal level for line transmission with minimal distortion at 2 mV MIC input |
| Receive Gain | 12 dB typical, adjustable from –8 to +12 dB - supports variable earpiece impedance and volume tuning |
| Frequency Response | ±0.5 dB over 300–3400 Hz - meets ITU-T G.107 loudness rating requirements for voiceband fidelity |
| Line Current Operation | Functional down to 8 mA - allows compatibility with legacy central office battery feed under high-loop-resistance conditions |
| VMP Output | 3.4 V regulated, 4 mA max - powers external microcontrollers or logic without auxiliary supply |
| DTMF Gain | 41.7 dB typical - ensures robust confidence-tone delivery to receiver during dialing |
| CMRR (MIC Amp) | 60–80 dB - rejects common-mode noise on balanced MIC1/MIC2 inputs |
Pinout & Package
U4037B-NFLG3Y is housed in a Pb-free SO24 package (15.55 × 7.5 mm, 1.27 mm pitch, 2.35 mm height), optimized for surface-mount assembly in compact telephone handsets and base units.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| MIC1 / MIC2 | Inverting / non-inverting mic amp inputs | Accepts balanced electret microphone signal; 50 kΩ input resistance enables direct connection without bias network |
| RECO1 / RECO2 | Differential receiver amplifier outputs | Drives 68 nF + 100 Ω earpiece load differentially; 40 Ω output resistance ensures stable termination |
| AGA | Line-current gain adjustment node | Resistor-to-GND here sets automatic gain change range (±6 dB max) to compensate for loop resistance variation |
| ST | Sidetone reduction control input | 25 kΩ input resistance allows simple RC network to adjust local feedback attenuation independently of gain |
| PD | Power-down enable (active high) | Asserting PD shorts VL internally and cuts VB/VMP current - reduces standby consumption to 300 µA |
| VMP | Regulated 3.4 V supply output | Provides clean, low-noise power for MCU or peripheral logic; rated 4 mA in speech mode |
Key Features
| Feature | Design Value |
|---|---|
| Symmetrical microphone input | Enables noise-rejecting differential electret mic interface without external balun or transformer |
| Anti-clipping in transmit path | 0.5 ms attack / 9 ms release time prevents audio saturation during loud speech bursts |
| Built-in ear protection | Clips differential output at 2.2 Vrms to prevent acoustic trauma from high-level ring signals |
| Adjustable sidetone suppression | Independent of send/receive gain settings - maintains natural talker feedback across line conditions |
| Tone-ringer interface with 2-bit volume control | VOL1/MU-VOL2 pins select –24 dB to 0 dB ringer output steps - eliminates external DAC or attenuator |
Applications
| Telephone Handset Audio Processing | Wired Desk Phone Base Unit |
|---|---|
Use Scenario: Full-duplex voice communication in analog corded telephone handsets with electret microphone and dynamic earpiece. IC Role / Device Role / Timing Role: Primary analog signal processor - handles microphone preamplification, line coupling, sidetone generation, receiver amplification, and ear protection. Use Value: Eliminates need for discrete op-amps, transformers, and protection diodes; supports operation from 8 mA line current enabling use in long-loop installations. | Use Scenario: Central audio processing in desktop telephone base units requiring ringer drive, DTMF decoding interface, and mute control. IC Role / Device Role / Timing Role: Integrated speech and ringer controller - provides differential ringer output (OUT1/OUT2), DTMF input (DTMF pin), and mute activation (MU/VOL2 pin). Use Value: Reduces BOM count by integrating tone-ringer driver, DTMF amplifier, and 2-bit ringer volume DAC - no external buzzer driver or DTMF buffer required. |
| Central Office Line Card Interface | Emergency Telephone Station |
Use Scenario: Analog line interface module in telecom line cards where space and component count are constrained. IC Role / Device Role / Timing Role: Subscriber line interface IC (SLIC) analog front-end - manages line voltage sensing (VL), impedance matching (IMP), and line-loss compensation (AGA). Use Value: Supports automatic gain adaptation across 14–100 mA line currents; built-in IMP and IND pins simplify Z-balancing for hybrid echo cancellation. | Use Scenario: Ruggedized emergency phone in public infrastructure (e.g., elevator, tunnel) requiring fail-safe audio and low-power standby. IC Role / Device Role / Timing Role: Low-quiescent-power telephone interface - enables PD-mode sleep (300 µA), ear protection, and reliable DTMF signaling under marginal line conditions. Use Value: Maintains functionality at 8 mA line current and includes built-in anti-clipping and ear protection - critical for safety-compliant voice interfaces. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar telephone line interface applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SLIC3101-IM | Higher integration: includes digital interface (SPI), internal ADC/DAC, and programmable DSP-based echo cancellation | Requires microcontroller firmware; not line-powered - needs external DC supply | Choose SLIC3101-IM when digital control, echo cancellation, or VoIP gateway compatibility is required |
| TP3067CP | Analog-only PCM codec; no line feed, ringer drive, or AGA-based gain control - requires external SLIC and ringer | Used in TDM-based systems with separate line interface; lacks ear protection and anti-clipping | Choose TP3067CP only when interfacing to an existing SLIC and ringer circuit, not as a full subscriber set solution |
Compared with SLIC3101-IM and TP3067CP, the U4037B-NFLG3Y uniquely delivers complete analog telephone set functionality - line power harvesting, ringer drive, DTMF interface, and ear protection - in a single SO24 IC without external transformers or digital control overhead.
Availability
U4037B-NFLG3Y is available at Aetrix Electronics and suitable for telephone handset design, wired desk phone manufacturing, and emergency communication system development requiring stable component supply and long-term lifecycle support.
Supply support for U4037B-NFLG3Y 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
Atmel Corporation - acquired by Microchip Technology in 2016 - specialized in high-reliability mixed-signal ICs for communications, automotive, and industrial applications.
The U4037B-NFLG3Y belongs to Atmel's CORD (Communications, Off-Hook, Ringing, Dialing) product line, designed specifically to replace discrete analog telephony circuits in POTS telephone sets with single-chip integration.
FAQ
What is the minimum line current required for U4037B-NFLG3Y to operate reliably?
The U4037B-NFLG3Y operates reliably down to 8 mA line current, maintaining specified receive gain (10.5–13.5 dB) and functional speech path integrity. Below this threshold, VMP regulation degrades and microphone preamplifier bias may become unstable. This low-current capability enables deployment in high-resistance telephone loops exceeding 3 km.
How does the AGA pin enable automatic line-loss compensation in U4037B-NFLG3Y?
The AGA pin on U4037B-NFLG3Y connects to a resistor-to-GND that sets the reference point for automatic gain adjustment. As line current increases from 14 to 100 mA, the internal circuit reduces transmit and receive gain by up to 6 dB - compensating for reduced line loss and preventing overdriving the central office interface. Measured ∆GTI = –5.8 dB typical at 100 mA confirms this behavior.
Can U4037B-NFLG3Y drive a standard 600 Ω telephone line directly?
No - U4037B-NFLG3Y is not a line driver IC and does not meet full POTS line interface specifications (e.g., -14 dBm output, 600 Ω impedance match, longitudinal balance). It requires external hybrid circuitry or transformer coupling to interface with the tip/ring line. Its VL, IMP, and IND pins support impedance adaptation but do not replace a compliant SLIC.
What is the purpose of the MU/VOL2 pin on U4037B-NFLG3Y, and how is it used?
The MU/VOL2 pin on U4037B-NFLG3Y serves dual function: (1) as 2-bit ringer volume control (codes 00 to 11 yield –24 dB to 0 dB steps), and (2) as microphone mute input - driven high during DTMF transmission to disable the microphone amplifier while routing DTMF tones to the line and receiver as confidence signal.
Does U4037B-NFLG3Y include built-in protection against acoustic feedback or loudspeaker damage?
Yes - U4037B-NFLG3Y includes two protection mechanisms: (1) ear protection limiting differential output (RECO1/RECO2) to 2.2 Vrms to prevent acoustic trauma, and (2) anti-clipping circuitry in the transmit path with 0.5 ms attack time to suppress peak microphone overdrive. These are confirmed in Electrical Characteristics tables (EP = 2.2 Vrms, TXACL timing).
U4037B-NFLG3Y Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Speech and Ringer Circuit
- Interface:
- -
- Number of Circuits:
- 1
- Voltage - Supply:
- 3.1V ~ 3.6V
- Current - Supply:
- -
- Power (Watts):
- 520 W
- Operating Temperature:
- -25°C ~ 75°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SO
U4037B-NFLG3Y FAQ
1.How can I place an order for U4037B-NFLG3Y through Aetrix?
Please submit a Request for Quotation (RFQ) for U4037B-NFLG3Y 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 U4037B-NFLG3Y reliable?
The price and inventory of U4037B-NFLG3Y are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for U4037B-NFLG3Y is usually 5 days.
3.What payment methods are accepted for U4037B-NFLG3Y?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for U4037B-NFLG3Y transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for U4037B-NFLG3Y?
U4037B-NFLG3Y orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your U4037B-NFLG3Y 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 U4037B-NFLG3Y?
For technical support, including U4037B-NFLG3Y datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your U4037B-NFLG3Y requirements.
6.How does Aetrix verify that U4037B-NFLG3Y is sourced from the original manufacturer or authorized distributors?
All U4037B-NFLG3Y 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 U4037B-NFLG3Y meets industry standards.
7.What is the process for return or replacement of U4037B-NFLG3Y?
All U4037B-NFLG3Y units undergo pre-shipment inspection (PSI). If there is an issue with U4037B-NFLG3Y, 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 U4037B-NFLG3Y part is unused and in its original packaging.
Return procedure for U4037B-NFLG3Y:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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