TA2022SMPS Audio Amplifier Module v1.3
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Amplifier Description:
TA2022SMPS Class T Stereo Audio Amplifier is built around TA2022SMPS, dedicated digital audio power
amplifier. The main blocks of this amplifier are: Input stage which has the role to adapt the impedance of the
amplifier, amplify and invert the input signal to match the level required by the TA2022 IC, TA2022 Power amplifier
stage which is the main stage of the board, Switched-Mode power supply, which supply power for the TA2022
Power stage, Input stage, and housekeeping and protection circuits which include the Speaker delay connect and
protection circuit, Mute stage and Status LED’s.
The audio input signal is provided to the TA2022SMPS Powered Amplifier Board through the small 3 pin
plug-in type connector called Input at pin 3 for the Left channel and pin 1 for the Right channel. As can be seen
from the board layout diagram, the input is placed next to the volume potentiometer to minimize the length of the
noise susceptible traces leading to better S/N ratio. The audio signal is 180° inverted for left channel only in within
the TA2022 IC, amplified and input impedance matched to 10KΩ. The audio signal on the Right channel is twice
180° inverted, once in the input stage and then again 180° inverted in the TA2022 IC, bringing the output signal for
the Right channel in phase with Input signal. The Left speaker negative terminal must be connected to Left output
and the Left speaker positive terminal must be connected to GND. There are two main reasons for driving the
TA2022 amplifier left channel 180° out of phase: to avoid bus pumping phenomenon, which otherwise would
compromise the sound quality and could affect reliability if the amplifier would be extensively used with high
power low frequency content, such as for subwoofer applications, then easy and straightforward BTL
implementation without any other changes, setting or modification required to the TA2022 Powered amplifier. For
BTL connection the speaker must be connected across left output which will become negative output and right
output which will become positive output. No GND connection is required or allowed in BTL mode. Input signal will
be supplied to both Inputs connected together.
The TA2022SMPS amplifier Gain is equal with the product of TA2022 power stage gain and the input
preamplifier stage. The TA2022 power stage gain is 18.6 V/V and the input preamplifier stage gain is 2. The overall
gain is 37.2 V/V or 31.4 dB. To achieve the rated power or 90W per channel on 4Ω impedance the input signal
amplitude must be 500mV. The input signal amplitude required for BTL operation will be the same, 500mV but the
Input impedance will be just half, 5KΩ because both Left and Right Inputs must be paralleled. This is a fairy
sensitive input amplifier and allows all kind of sources including latest mobile devices (Smartphone, tablet
computers) which have very low output signal level to drive this amplifier without requiring an additional
preamplifier or buffer stage. If the signal source output lever is found to be too high (severe distortion and clipping
before reaching the maximum level of the volume potentiometer) a very simple attenuator can be introduced, by
just connecting one 10-20KΩ resistor in series with each signal input.
The TA2022 amplifier section operation was explained in very similar TA2022 Amplifier manual, which can
be downloaded from here: http://www.connexelectronic.com/documents/TA2022_Audio_Amplifier_Module.pdf
Amplifier Efficiency:
The on-board Switched Mode Power Supply is resonant half bridge type, operating at very high switching
frequency allowing maximum efficiency and lowest EMI. Although is just few cm distance from the amplifier and
preamplifier stage, it operates so quiet that there is no audible difference if the amplifier is powered from the on-
board SMPS or a remotely placed high performance low-noise power supplies. The total efficiency from mains to
speaker is up to 86% when using 8Ω speakers and up to 82.5% when using 4Ω speakers. The SMPS efficiency alone
is over 93% from 40 to 70% load. The total idle power consumption of TA2022SMPS Powered amplifier module is
just below 8W. The idle power consumption of the SMPS alone is around 2W, another watt is consumed by the
speaker protection circuit and the voltage regulators and preamplifier stage and the rest of ~ 4.5W is the idle
power consumed by the TA2022 amplifier stage and auxiliary circuits. This is the lowest power consumption
possible to achieve with TA2022 IC based amplifier and one of the lowest idle power consumption among any 50-
200W per channel class D powered amplifiers available on the market. For comparisons, if the TA2022 IC based
amplifier would be supplied from a linear power supply consisting of mains power transformer, Rectifier Bridge
and capacitors, the idle power consumption would be at least 15-20W because the bulky mains transformers
waste about 5-10% of their rated power as idle power loss. The maximum overall efficiency reached with a
TA2022 IC based amplifier supplied from a linear power supply stage is around 72-77% far below the efficiency of
the current Powered Amplifier module. Not to mention about heavy weight and poor mains voltage regulation.
