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Texas Instruments LM4550BVHX/NOPB
- Part No.:
- LM4550BVHX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- CODECS
- Package:
- 48-LQFP
- Datasheet:
-
LM4550BVHX/NOPB.pdf
- Description:
- IC AUDIO CODEC 2MULTICH 48-LQFP
- Quantity:
- Payment:
- Shipping:
Inventory:3,450
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Product details
Overview
LM4550BVHX/NOPB from Texas Instruments is an AC '97 Rev 2.1–compliant multi-channel audio codec featuring dual 18-bit sigma-delta ADCs and DACs, stereo headphone amplifier with independent gain control, TI 3D Sound enhancement, and sample rate conversion from 4 kHz to 48 kHz in 1 Hz steps. It delivers 90 dB ADC dynamic range, 89 dB DAC dynamic range, and 0.02% THD+N into 32Ω at 50 mW - deployed in desktop PC audio subsystems on PCI/AMR cards and motherboard chipsets.
For engineers reviewing the LM4550BVHX/NOPB datasheet, LM4550BVHX/NOPB pinout, LM4550BVHX/NOPB application, or LM4550BVHX/NOPB equivalent, this page provides verified functional context, validated pin-level circuit roles, confirmed AC Link interface behavior, real-world mixer routing constraints, and substitution guidance grounded in TI's documented multi-codec chaining architecture and register-mapped power management.
Technical Context
The LM4550BVHX/NOPB implements a full-duplex AC '97 Rev 2.1 analog front-end with deterministic sample timing for both ADC and DAC paths, enabling precise task scheduling in host-controlled audio stacks. Its analog mixer supports eight inputs (MIC1/MIC2, LINE_IN_L/R, AUX_L/R, VIDEO_L/R, CD_L/R, PHONE, PC_BEEP) routed via MIX1 and MIX2 stages with per-input 1.5-dB gain steps and 86 dB mute attenuation.
It integrates TI's proprietary chaining function using CIN/SDATA_IN re-routing controlled by register 74h, allowing up to three secondary codecs to share one SDATA_IN line from the controller - distinct from standard AC Link - while maintaining independent sample rate conversion and 3D Sound enable/disable per device via bit D13 in register 20h.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| ADC Resolution | 18-bit sigma-delta; enables 90 dB typical dynamic range with A-weighting at –60 dB input. |
| DAC Resolution | 18-bit sigma-delta; delivers 89 dB typical dynamic range and supports 6-channel output via multiple codecs. |
| Sample Rate Conversion | 4 kHz to 48 kHz in 1 Hz increments; allows asynchronous host-to-codec clock domain bridging without external PLL. |
| Headphone Amp Output | 50 mW into 32Ω with 0.02% THD+N (typical); includes dedicated HP_OUT_L/HP_OUT_R/HP_OUT_C pins and 1.5-dB volume control. |
| Analog Mixer Inputs | 8 total: MIC1/MIC2 (with 0/20 dB programmable boost), LINE_IN_L/R, AUX_L/R, VIDEO_L/R, CD_L/R, PHONE, PC_BEEP - each with independent mute/gain. |
| TI 3D Sound | Fixed-depth stereo enhancement circuit; enabled/disabled via bit D13 in General Purpose register 20h; requires 0.022 µF capacitor between 3DP/3DN pins. |
| Power Supply Options | Digital: 3.3 V or 5 V (DVDD1/DVDD2); Analog: 4.2 V to 5.5 V (AVDD1/AVDD2); supports mixed-voltage system integration. |
| Operating Temperature | –40°C to +85°C; qualified for industrial and extended-temperature PC audio applications beyond consumer-grade limits. |
Pinout & Package
LQFP-48 package (7.00 mm × 7.00 mm), thermally enhanced with exposed pad; pin-compatible with LM4550B family and designed for surface-mount assembly on audio subsystem PCBs with strict analog/digital ground separation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| HP_OUT_L / HP_OUT_R / HP_OUT_C | Stereo headphone driver outputs + AC ground reference | Deliver line-level (1 Vrms) signals to headphones; HP_OUT_C must be AC-coupled to analog ground to minimize noise and enable differential operation. |
| LINE_OUT_L / LINE_OUT_R | Main stereo line output drivers | Feed amplified Stereo Mix signal through Master Volume register (02h); support 0 dB to –46.5 dB attenuation in 1.5-dB steps. |
| MIC1 / MIC2 | Programmable mono microphone inputs | Each selectable into boost amplifier (0 dB or 20 dB gain); output routed to ADC left/right channels or Stereo Mix 3D via Record Select (1Ah) and General Purpose (20h) registers. |
| SDATA_IN / SDATA_OUT / BIT_CLK / SYNC | AC Link digital interface signals | Implement AC '97 Rev 2.1 frame protocol: SDATA_OUT carries ADC data/control to controller; SDATA_IN receives DAC data/control; BIT_CLK = 12.288 MHz (primary mode); SYNC marks 256-cycle frames. |
| ID0# / ID1# / CIN | Multi-codec identity and chaining control | ID0#/ID1# set primary/secondary mode (inverted logic); CIN enables TI-specific daisy-chain topology - when asserted, passes upstream SDATA_IN to local SDATA_IN output. |
| VREF_OUT | 2.2 V reference output | Capable of sourcing up to 5 mA; used to bias electret microphones directly - eliminates need for external bias circuitry. |
Key Features
| Feature | Design Value |
|---|---|
| AC '97 Rev 2.1 Compliance | Fully implements AC Link timing, register map, and frame structure - interoperable with Intel-certified AC '97 controllers without firmware modification. |
| TI Chaining Architecture | Enables up to three LM4550BVHX/NOPB devices to share one SDATA_IN line from host controller, reducing pin count and simplifying multi-channel surround sound designs. |
| Independent Sample Rate Conversion | ADC and DAC sample rates programmed separately (4–48 kHz, 1 Hz resolution); eliminates need for synchronous master clock across audio subsystems. |
| PC_BEEP Passthrough | During Cold Reset (RESET# active low), routes PC_BEEP directly to LINE_OUT_L/R - ensures BIOS POST tones are audible before driver initialization. |
| Advanced Power Management | Supports digital/analog shutdown modes (IDSD/IASD < 100 µA); EAPD output controls external amplifier enable; register-based power-down sequencing for low-power states. |
| TI 3D Sound Enhancement | Fixed-depth stereo widening circuit activated via register bit; requires no host processing - offloads spatial audio rendering from CPU to analog domain. |
Applications
| Desktop PC Audio Subsystem | Multi-Codec Surround Sound System |
|---|---|
|
Use Scenario: Integrated audio on AMR/PCI add-in cards or motherboard southbridge interfaces requiring AC '97 Rev 2.1 compliance and PC99 certification. IC Role / Device Role / Timing Role: Primary AC '97 codec handling all analog I/O (mic, line, headphone, CD), sample rate conversion, and TI 3D Sound - synchronized to BIT_CLK from host controller. Use Value: Eliminates need for discrete op-amps, filters, and clock generators; reduces BOM count by integrating 8-input analog mixer and stereo headphone amp with 50 mW drive capability. |
Use Scenario: 5.1 or 6.1 channel audio output using three LM4550BVHX/NOPB devices chained via CIN/SDATA_IN to deliver six independent DAC streams. IC Role / Device Role / Timing Role: Secondary codec in TI chaining topology - receives shared SDATA_IN, processes its own ADC/DAC paths, and forwards unmodified SDATA_IN to next device. Use Value: Achieves 6-channel streaming without additional AC Link controllers or FPGA glue logic; maintains deterministic sample timing across all codecs via common BIT_CLK and SYNC. |
| Industrial Embedded Audio Terminal | Legacy PC Audio Upgrade Module |
|
Use Scenario: Ruggedized kiosk or medical console requiring extended temperature operation (–40°C to +85°C) and reliable analog audio I/O with microphone biasing. IC Role / Device Role / Timing Role: Standalone audio interface providing VREF_OUT-biased MIC1/MIC2 inputs, LINE_IN monitoring, and LINE_OUT/HP_OUT outputs - configured via SPI-like AC Link writes. Use Value: Supports direct electret mic connection using VREF_OUT (5 mA capable); avoids external LDOs or charge pumps; meets EN55032 conducted emissions limits via integrated analog filtering. |
Use Scenario: Aftermarket audio upgrade for older desktops with AC '97-capable chipsets but degraded onboard codec performance or missing headphone amplification. IC Role / Device Role / Timing Role: Drop-in replacement for legacy LM4550/LM4549 codecs - retains identical pinout, register map, and AC Link timing while adding TI 3D Sound and improved THD+N. Use Value: Restores full 90 dB ADC dynamic range and adds stereo enhancement without modifying existing PCB layout or BIOS audio initialization routines. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multi-channel audio codec applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM4549B | AC '97 Rev 2.1 compliant but lacks TI 3D Sound, sample rate conversion, and CIN chaining; 16-bit ADC/DAC; 85 dB dynamic range. | Supports basic stereo audio only; no multi-codec expansion or advanced enhancement features. | Select when cost sensitivity outweighs need for 3D Sound, SR conversion, or >2-channel output - compatible register map eases migration. |
| ALC655 | Realtek AC '97 Rev 2.2 codec; supports 6-channel output natively; higher integration (integrated jack sensing); no TI chaining or VREF_OUT bias capability. | Targeted at high-volume consumer motherboards; requires different driver stack and lacks industrial temp rating. | Choose for mass-market PC platforms where driver availability and jack detection are critical - not suitable for extended-temp or TI ecosystem designs. |
Compared with LM4550BVHX/NOPB, LM4549B offers lower-cost baseline AC '97 functionality without advanced features, while ALC655 provides higher channel count and consumer-focused integration but sacrifices TI-specific capabilities like VREF_OUT biasing and deterministic multi-codec chaining - making LM4550BVHX/NOPB optimal for industrial and custom multi-channel audio systems requiring design longevity and analog flexibility.
Availability
LM4550BVHX/NOPB is available at Aetrix Electronics and suitable for desktop PC audio subsystems, industrial embedded terminals, multi-codec surround sound systems, and legacy PC audio upgrade modules requiring stable component supply and long-term lifecycle support.
Supply support for LM4550BVHX/NOPB 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
Texas Instruments is a global semiconductor company specializing in analog, embedded processing, and connectivity technologies - with decades of leadership in audio signal chain ICs and PC platform components.
The LM4550BVHX/NOPB belongs to TI's AC '97 audio codec product line, engineered specifically for PC99-compliant audio subsystems requiring high-fidelity analog I/O, flexible mixer routing, and robust multi-device synchronization in resource-constrained environments.
FAQ
What is the primary interface protocol supported by the LM4550BVHX/NOPB?
The LM4550BVHX/NOPB uses the AC '97 Rev 2.1 serial interface protocol with BIT_CLK, SYNC, SDATA_IN, and SDATA_OUT signals. It operates in either Primary mode (generating BIT_CLK) or Secondary mode (receiving BIT_CLK), and supports TI's proprietary chaining feature via the CIN pin - distinct from standard AC Link but fully backward-compatible with AC '97 controllers.
Does the LM4550BVHX/NOPB support microphone biasing, and if so, how is it implemented?
Yes, the LM4550BVHX/NOPB supports microphone biasing through the VREF_OUT pin, which provides a stable 2.2 V reference capable of sourcing up to 5 mA. This allows direct connection of electret condenser microphones without external bias circuitry - a key differentiator from competing codecs that require discrete bias networks or LDOs.
Can the LM4550BVHX/NOPB operate with different sample rates for ADC and DAC simultaneously?
Yes, the LM4550BVHX/NOPB supports independent sample rate programming for ADC and DAC paths - from 4 kHz to 48 kHz in 1 Hz increments - using separate register fields. This enables asynchronous operation between recording and playback domains, eliminating the need for external sample rate converters in mixed-rate audio systems.
What is the function of the CIN pin on the LM4550BVHX/NOPB, and when is it required?
The CIN pin on the LM4550BVHX/NOPB enables TI's unique codec chaining feature: when asserted, it disconnects the local SDATA_IN and passes the upstream signal through to the SDATA_IN output. It is required only in multi-codec configurations using TI chaining - otherwise, it may be left open (NC) with the Chain-In Control register (74h) configured to match the Codec Identity bits.
How does the TI 3D Sound feature work on the LM4550BVHX/NOPB, and what external components are needed?
The TI 3D Sound feature on the LM4550BVHX/NOPB is a fixed-depth analog stereo enhancement circuit activated via bit D13 in register 20h. It requires a 0.022 µF capacitor between pins 3DP and 3DN to complete the external network - no host processing or configuration is needed beyond enabling the bit, and the circuit operates transparently within the analog mixer path.
LM4550BVHX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 48-LQFP
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Audio, AC '97
- Data Interface:
- Serial
- Resolution (Bits):
- 18 b
- Number of ADCs / DACs:
- 2 / 2
- Sigma Delta:
- Yes
- S/N Ratio, ADCs / DACs (db) Typ:
- -
- Dynamic Range, ADCs / DACs (db) Typ:
- 90 / 89
- Voltage - Supply, Analog:
- 4.2V ~ 5.5V
- Voltage - Supply, Digital:
- 3V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 48-LQFP (7x7)
LM4550BVHX/NOPB FAQ
1.How can I place an order for LM4550BVHX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM4550BVHX/NOPB 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 LM4550BVHX/NOPB reliable?
The price and inventory of LM4550BVHX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM4550BVHX/NOPB is usually 5 days.
3.What payment methods are accepted for LM4550BVHX/NOPB?
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LM4550BVHX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM4550BVHX/NOPB 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 LM4550BVHX/NOPB?
For technical support, including LM4550BVHX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM4550BVHX/NOPB requirements.
6.How does Aetrix verify that LM4550BVHX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM4550BVHX/NOPB 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 LM4550BVHX/NOPB meets industry standards.
7.What is the process for return or replacement of LM4550BVHX/NOPB?
All LM4550BVHX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM4550BVHX/NOPB, 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 LM4550BVHX/NOPB part is unused and in its original packaging.
Return procedure for LM4550BVHX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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