Pam8603m, Application information – Diodes PAM8603M User Manual

Page 9

PAM8603M

Document number: DSxxxxx Rev. 1 - 1

9 of 14

November 2012

PAM8603M

A Product Line of

Diodes Incorporated

Application Information

1. When the PAM8603M works with LC filters, it should be connected with the speaker before it is powered on, otherwise it will be damaged

easily.

2. When the PAM8603M works without LC filters, it's better to add a ferrite chip bead at the outgoing line of speaker to suppress the possible

electromagnetic interference.

3. The input signal should not be too high. If too high, it will cause the clipping of output signal when increasing the volume. Because the DC

volume control of the PAM8603M has big gain, it will make the device damaged.

4. When testing the PAM8603M without LC filters by using resistor instead of speaker as the output load, the test results, e.g. efficiency, will be

worse than those using speaker as load.

Test Setup for Performance Testing

Notes:

1. The AP AUX-0025 low pass filter is necessary for class-D amplifier measurement done by AP analyzer.

2. Two 22µH inductors are used in series with load resistor to emulate the small speaker for efficiency measurement.

Mute Operation

The

MUTE

pin is an input for controlling the output state of the PAM8603M. A logic low on this pin disables the outputs, and a logic high enables

the outputs. This pin may be used as a quick disable or enable of the outputs without a volume fade. Quiescent current is listed in the electrical

characteristic table. The

MUTE

pin can be left floating due to the internal pull-up.

For better power-off pop performance, the amplifier should be placed in the mute mode prior to removing the power supply.

Shutdown Operation

In order to reduce power consumption while not in use, the PAM8603M contains shutdown circuitry to turn off the amplifier's bias circuitry. The

amplifier is turned off when logic low is placed on the

SHDN

pin. By switching the

SHDN

pin connected to GND, the PAM8603M supply current

draw will be minimized in idle mode. The

SHDN

pin can be left floating due to the pull-up.

Power Supply Decoupling

The PAM8603M is a high performance CMOS audio amplifier that requires adequate power supply decoupling to ensure the output THD and

PSRR as low as possible. Power supply decoupling affects low frequency response. Optimum decoupling is achieved by using two capacitors of

different types that target different noise on the power supply leads. For higher frequency transients, spikes, or digital hash on the line, a good

low equivalent-series resistance (ESR) ceramic capacitor, typically 1.0µF, placed as close as possible to the device V

terminal works best. For

filtering lower-frequency noise signals, a large capacitor of 10µF (ceramic) or greater placed near the audio power amplifier is recommended.