TPA2025D1_15 Datasheet, PDF (11/29 Pages) Texas Instruments – TPA2025D1 2-W Constant Output Power Class-D Audio Amplifier With Class-G Boost Converter and Battery Tracking AGC

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TPA2025D1
SLOS717B – AUGUST 2011 – REVISED DECEMBER 2014
9 Parameter Measurement Information
All parameters are measured according to the conditions described in the Specifications section.
Many audio analyzers will not give the correct readings on a Class-D amplifier without additional filtering, even if
they have an internal low-pass filter. A RC 30kHz low-pass filter (100-Ω, 47n-F) is implemented to reduce the
remaining noise frequencies from the PWM carrier signal. This filter was used on each output for the data sheet
graphs.
10 Detailed Description
10.1 Overview
The TPA2025D1 is a constant output, high efficiency Class-D audio amplifier with battery tracking AGC
technology and an integrated Class-G boost converter. This features give the device a great performance and
enhances efficiency at low output power. The TPA2025D1 can drive up to 1.9 W into an 8-Ω speaker (1%
THD+N).
The built-in boost converter operates from a battery supply voltage and generates a higher output voltage PVDD
at 5.75 V that drives the supply voltage of the Class-D amplifier. This provides a louder audio output than a
stand-alone amplifier directly connected to the battery.
The battery tracking AGC adjusts the Class-D gain to limit battery current at lower battery voltage. This lets the
device to extend the battery life while playing audio, typically with 85% efficiency. When the battery voltage is
below a certain threshold voltage, The TPA2025D1 lowers the audio loudness. The threshold is selectable with
an external pin.
The TPA2025D1 has an integrated low-pass filter to improve the RF rejection and reduce DAC out-of-band
noise, increasing the signal-to-noise ratio (SNR). The features included in this device allow it to be used in a wide
range of portable applications.
10.2 Functional Block Diagram
VBAT
SW
EN
AGC
IN+
IN-
Bias
Control
VBAT
Monitor
AGC
PVDD
+
–
AGND
BGND
Adaptive
Boost
Converter
Oscillator
PWM
H-
Bridge
PVDD
OUT+
OUT-
PGND
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