PAM8404

Document number: DSxxxxx Rev. 1 - 1

14 of 18

www.diodes.com

November 2012

© Diodes Incorporated

PAM8404

A Product Line of

Diodes Incorporated

Application Information

POP and Click Circuitry

The PAM8404 contains circuitry to minimize turnon and turn-off transients or “click and pops”, where turn-on refers to either power supply turnon

or device recover from shutdown mode. When the device is turned on, the amplifiers are internally muted. An internal current source ramps up

reference voltage is stable, the device will begin full operation. For the best power-off pop performance, the amplifier should be set in shutdown

mode prior to removing the power supply voltage.

PCB Layout Guidelines

Grouding

It is recommended to use plane grounding or separate grounds. Do not use one line connecting power GND and analog GND. Noise currents in

the output power stage need to be returned to output noise ground and nowhere else. When these currents circulate elsewhere, they may get

into the power supply, or the signal ground, etc, even worse, they may form a loop and radiate noise. Any of these instances results in degraded

amplifier performance. The output noise ground that the logical returns for the output noise currents associated with Class-D switching must tie

to system ground at the power exclusively. Signal currents for the inputs, reference need to be returned to quite ground. This ground only ties to

the signal components and the GND pin. GND then ties to system ground.

Power Supply Line

routed as short and thick as possible. For the power line layout, just imagine water stream, any barricade placed in the trace (shown in Figure 2)

could result in the bad performance of the amplifier.

Figure 2. Power Line

Component Placement

Decoupling capacitors-As previously described, the high-frequency 1μF decoupling capacitors should be placed as close to the power supply

Input capacitors need to be placed very close to input pins.

Output filter - The ferrite EMI filter should be placed as close to the output terminals as possible for the best EMI performance, and the capacitors

used in the filters should be grounded to system ground.