TPA6138A2 - 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
  Resistors
• 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
  Control
• Space-Saving TSSOP Package