The LM4550B device is an audio codec for PC systems which is fully PC99 compliant and performs the analog intensive functions of the AC ’97 Rev 2.1 architecture. Using 18-bit Sigma-Delta ADCs and DACs, the LM4550B provides 90 dB of Dynamic Range.

The LM4550B was designed specifically to provide a high quality audio path and provide all analog functionality in a PC audio system. It features full duplex stereo ADCs and DACs and analog mixers with access to 4 stereo and 4 mono inputs.

Each mixer input has separate gain, attenuation and mute control and the mixers drive 1 mono and 2 stereo outputs, each with attenuation and mute control. The LM4550B provides a stereo headphone amplifier as one of its stereo outputs and also supports TI’s 3D sound stereo enhancement and a comprehensive sample rate conversion capability. The sample rate for the ADCs and DACs can be programmed separately with a resolution of 1 Hz to convert any rate from 4 kHz to 48 kHz. Sample timing from the ADCs and sample request timing for the DACs are completely deterministic to ease task scheduling and application software development. These features together with an extended temperature range also make the LM4550B suitable for non-PC codec applications.

The LM4550B features the ability to connect several codecs together in a system to provide up to 6 simultaneous channels of streaming data on output frames (controller to codec) for surround sound applications. Such systems can also support up to 8 simultaneous channels of streaming data on input frames (codec to controller). Multiple codec systems can be built either using the standard AC Link configuration (that is, of one serial data signal to the controller per codec) or using a unique TI feature for chaining codecs together. This chain feature shares only a single data signal to the controller among multiple codecs.

The AC ’97 architecture separates the analog and digital functions of the PC audio system allowing both for system design flexibility and increased performance.

• AC ’97 Rev 2.1 Compliant
• High Quality Sample Rate Conversion From 4 kHz to 48 kHz in 1 Hz Increments
• Supports up to 6 DAC Channel Systems With Multiple LM4550Bs or With Other TI LM45xx Codecs
• Unique TI Chaining Function Shares a Single Controller SDATA_IN Pin Among Multiple Codecs
• Stereo Headphone Amp With Separate Gain Control
• TI’s 3D Sound Stereo Enhancement Circuitry
• Advanced Power Management Support
• External Amplifier Power-Down (EAPD) Control
• PC Beep Passthrough to Line Out During Initialization or Cold Reset
• Digital 3.3-V and 5-V Supply Options
• Extended Temperature: –40°C ≤ TA ≤ 85°C
• Key specifications
  • Analog Mixer Dynamic Range, 97 dB (Typical)
  • DAC Dynamic Range, 89 dB (Typical)
  • ADC Dynamic Range, 90 dB (Typical)
  • Headphone Amp THD+N at 50 mW, 0.02% (Typical) into 32Ω

• Number of ADC channels
• 2
• Number of DAC channels (#)
• 2
• Digital audio interface
• I2S
• Analog inputs
• 7
• Sampling rate (Max) (kHz)
• 48
• Rating
• Catalog
• Features
• Stereo headphone amplifier
• ADC SNR (Typ) (dB)
• 90
• DAC SNR (Typ) (dB)
• 89

LM4550B的完整型号有：LM4550BVH/NOPB、LM4550BVHX/NOPB、LM4550BVH，以下是这些产品的关键参数及官网采购报价：

LM4550BVH/NOPB，工作温度：-40 to 85，封装：LQFP (PT)-48，包装数量MPQ：250个，MSL 等级/回流焊峰值温度：Level-3-260C-168 HR，引脚镀层/焊球材料：SN，TI官网LM4550BVH/NOPB的批量USD价格：4.08（1000+）

LM4550BVHX/NOPB，工作温度：-40 to 85，封装：LQFP (PT)-48，包装数量MPQ：1000个，MSL 等级/回流焊峰值温度：Level-3-260C-168 HR，引脚镀层/焊球材料：SN，TI官网LM4550BVHX/NOPB的批量USD价格：3.4（1000+）

LM4550BVH，工作温度：-40 to 85，封装：LQFP (PT)-48，包装数量MPQ：250个，MSL 等级/回流焊峰值温度：Level-3-260C-168 HR，引脚镀层/焊球材料：SNPB，TI官网LM4550BVH的批量USD价格：5.27（1000+）

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