TPA6138A2 DIRECTPATH™ Headphone Driver with Adjustable Gain |


DIRECTPATH™ Headphone Driver with Adjustable Gain



The TPA6138A2 is a pop-free stereo headphone amplifier designed to allow the removal of the output dc-blocking capacitors for reduced component count and cost. The device is ideal for single-supply electronics where size and cost are critical design parameters.

Designed using TI’s patented DirectPath™ technology, The TPA6138A2 is capable of driving 25 mW into a 32-Ω load with 3.3-V supply voltage. The device has differential inputs and uses external gain-setting resistors that supports a gain range of ±1 V/V to ±10 V/V. Gain can be configured individually for each channel. The device can also be configured as a second-order low-pass filter and is ideal for interfacing with PWM audio sources. Audio output compiles with ±8-kV IEC ESD protection, requiring just a simple resistor-capacitor ESD protection circuit. The TPA6138A2 has built-in active-mute control for pop-free audio on/off control. The TPA6138A2 has an external undervoltage detector that mutes the output when the power supply is removed, ensuring a pop-free shutdown.

Using the TPA6138A2 in audio products can reduce component count considerably compared to traditional headphone amplifiers. The TPA6138A2 does not require a split-rail power supply or a dc blocking capacitor. The TPA6138A2 integrates its own charge pump to generate a negative supply rail that provides a clean, pop-free ground-biased audio signal.

The TPA6138A2 is available in a 14-pin TSSOP.


  • Stereo DirectPath™ Headphone Amplifier
    • 40 mW Into 32 Ω With 3.3-V Supply
  • Low THD+N < 0.01% at 10 mW Into 32 Ω
  • High SNR, >90 dB
  • Differential Input and Single-Ended Output
  • Adjustable Gain by External Gain-Setting
  • Configurable as a Second-Order Low-Pass Filter
    • Ideal for PWM Audio Sources
  • Low DC Offset, <1 mV
  • Ground-Referenced Outputs Eliminate DC-
    Blocking Capacitors
    • Reduce Board Area
    • Reduce Component Cost
    • Improve THD+N Performance
    • No Degradation of Low-Frequency Response
      Due to Output Capacitors
  • Short-Circuit Protection
  • Click- and Pop-Reduction Circuitry
  • External Undervoltage Mute
  • Active Mute Control for Pop-Free Audio On/Off
  • Space-Saving TSSOP Package

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Parametrics Compare all products in Headphone amps

Output power (W)
Analog supply (Min) (V)
Analog supply (Max) (V)
Operating temperature range (C)
Headphone channels
Volume control
Shutdown Current (ISD) (uA)
Iq per channel (Typ) (mA)
TPA6138A2 TPA6130A2 TPA6132A2 TPA6133A2 TPA6136A2 TPA6140A2 TPA6141A2 TPA6166A2
0.25     0.138     0.025     0.138     0.025     0.025     0.025     0.03    
3.6     2.5     2.3     2.5     5.5     2.5     2.5     1.7    
3.6     5.5     5.5     5.5     2.3     5.5     5.5     1.9    
80     109     100     109     100     105     105     92    
Catalog     Catalog     Catalog     Catalog     Catalog     Catalog     Catalog     Catalog    
-40 to 85     -40 to 85     -40 to 85     -40 to 85     -40 to 85     -40 to 85     -40 to 85     -40 to 85    
Stereo     Stereo     Stereo     Stereo     Stereo     Stereo     Stereo     Stereo    
No     Yes     No     No     No     Yes     No     Yes    
1     0.4     0.7     0.08     0.7     1     1     1    
Class-AB     Class-AB     Class-AB     Class-AB     Class-AB     Class-G     Class-G     Class-G    
14     2     1.05     4.2     1.05     0.6     0.6     1.2