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3.11 Audio Interface
Figure.3-11-1 Main Speaker Interface
Figure.3-11-2 Main Microphone & Receiver Interface
YDA145 (D-4H) is a digital audio power amplifier IC with maximum output of 2.1W
(R
L
=4Ώ)×1ch.
YDA145 has a “Pure Pulse Direct Speaker Drive Circuit” which directly drives speakers while
reducing distortion of pulse output signal and reducing noise on the signal, and realizes the
highest standard low distortion rate characteristics and low noise characteristics among digital
amplifier ICs for mobile use.
In addition, circuit design with fewer external parts can be made depend on the condition of use
because corresponds to filter less.
The YDA145 features Yamaha original non-clip output control function which detects output
signal clip due to the over level input signal and suppress the output signal clip automatically.
Also the non-clip output control function can adapt the output clip caused by power supply
voltage down with battery. This is the difference from the traditional AGC (Auto Gain Control) or
ALC (Auto Level Control) circuit.
YDA145 has the power-down function which can minimizes the power consumption in the
standby state.
As for protection function, overcurrent protection function for speaker output terminal,
overtemperatue protection function for inside of the device, and low supply voltage malfunction
preventing function are prepared.
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