The TPA2050D4 features a stereo Class-D power
amplifier along with a stereo DirectPath headphone
amplifier. The TPA2050D4 has two stereo single-ended (SE) inputs
that can be configured as one stereo differential input. Both input channels have a 32-step volume
control and the DirectPath headphone amplifier has a 4-level gain control for coarse volume adjustment. All
amplifiers have output short-circuit and thermal-overload
The Class-D amplifiers deliver 1.25 W into 8 Ω at 1% THD
from a 5.0 V supply, and 700 mW from 3.6 V. The
DirectPath headphone amplifier features an output voltage
limiter to reduce the maximum output power to one of
seven possible limits. The voltage limiter is programmed through the I2C
DirectPath eliminates the need for external DC- blocking
output capacitors to the headphones. The built-in charge
pump creates a negative supply voltage for the headphone
amplifier, allowing a 0-V DC bias at the output.
The DirectPath headphone amplifier gains are 0 dB
(default), -6 dB, -12 dB, and -20 dB, selected through the
I2C interface. This allows the headphone volume to be
different from the loudspeaker volume if both are used
The TPA2050D4 has a 2:1 input MUX for audio source selection. The MUX has mode control which directs
the input-to-output signal path. Mode and gain controls
operate from a 1.8 V compatible I2C interface.
The voltage supply range for both the Class-D amplifiers
and the headphone charge pump is 2.5 V to 5.5 V. The
Class-D amplifiers use a combined 7 mA and the
headphone amplifier uses 10 mA of typical quiescent
current. Total supply current reduces to less than 2µA.
The TPA2050D4YZK is available in a 25-ball
2.61 mm × 2.61 mm WCSP package.