LM49251 Stereo Audio Subsystem w/ Class G Headphone Amp & Class D Speaker Amp w/ Speaker Protection | TI.com

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Stereo Audio Subsystem w/ Class G Headphone Amp & Class D Speaker Amp w/ Speaker Protection



The LM49251 is a fully integrated audio subsystem designed for portable handheld applications such as cellular phones. Part of TI’s PowerWise family of products, the LM49251 utilizes a high efficiency class G headphone amplifier topology as well as a high efficiency class D loudspeaker.

The headphone amplifiers feature TI’s class G ground referenced architecture that creates a ground-referenced output with dynamic supply rails for optimum efficiency. The stereo class D speaker amplifier provides both a no-clip feature and speaker protection. The Enhanced Emission Suppression (E2S) outputs feature a patented, ultra low EMI PWM architecture that significantly reduces RF emissions.

The LM49251 features separate volume controls for the mono and stereo inputs. Mode selection, shutdown control, and volume are controlled through an I2C compatible interface.

Click and pop suppression eliminates audible transients on power-up/down and during shutdown. The LM49251 is available in an ultra-small 30-bump DSBGA package (2.55mmx3.02mm)


  • Class G Ground Referenced Headphone Outputs
  • E2S Class D Amplifier
  • No Clip Function
  • Power Limiter Speaker Protection
  • I2C Volume and Mode Control
  • Advanced Click-and-Pop Suppression
  • Micro-Power Shutdown

Key Specifications

  • Class G Headphone Amplifier, HPVDD = 1.8V, RL = 32Ω
    • IDDQHP: 1.15 mA (Typ)
    • Output Power, THD+N ≤ 1%: 20 mW (Typ)
  • Stereo Class D Speaker Amplifier RL = 8Ω
    • Output Power, THD+N ≤ 1%, LSVDD = 5.0V: 1.37 W (Typ)
    • Output Power, THD+N ≤ 1%, LSVDD = 3.6V: 680 mW (Typ)
    • Efficiency: 90% (Typ)

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Part number Order Audio input type Architecture Speaker channels (Max) Power stage supply (Min) (V) Power stage supply (Max) (V) Output power (W) Load (Min) (ohms) SNR (dB) THD + N @ 1 kHz (%) Iq (Typ) (mA) Control interface Closed/open loop Analog supply (Min) (V) Analog supply (Max) (V) PSRR (dB) Operating temperature range (C) Rating
LM49251 Order now Analog Input     Class-D     Stereo     2.7     5.5     1.37     4     98     0.02     1.15     I2C     Open     2.7     5.5     93     -40 to 85     Catalog