PAM8007

Document number: DSxxxxx Rev. 1 - 2

11 of 17

www.diodes.com

October 2012

© Diodes Incorporated

PAM8007

A Product Line of

Diodes Incorporated

Application Information

Mute Operation

The MUTE pin is an input for controlling the output state of the PAM8007. A logic low on this pin disables the outputs, and a logic high on this

pin 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 characteristics table. The MUTE pin can be left floating due to the internal pull-up.

For the best power on/off pop performance, the amplifier should be placed in the MUTE mode prior to turning on/off the power

supply.

Shutdown Operation

In order to reduce power consumption while not in use, the PAM8007 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 PAM8007 supply current

draw will be minimized in idle mode. The SHDN pin can be left floating due to the internal pull-up.

Line/Ear Operation

In order to control the speaker/headphone switch, the PAM8007 contains detect circuitry. When line/ear logic low, speaker actice; when logic

high, earphone active.

Power Supply Decoupling

The PAM8007 is a high performance CMOS audio amplifier that requires an adequate power supply decoupling to ensure the output THD and

PSRR are as low as possile. Power supply decoupling affects low frequency on the power supply leads for higher frey response. Optimum

decoupling is achieved by using two capacitors of different types that target different types of noise frequency tranisients, spike, or digital hash

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.

Large input capacitors are both expensive and space hungry for portable designs. Clearly, a certai sized capacitor is needed to couple in low

frequencies without severe attenuation. But in many cases the speakers used in portable systems, whether internal or external, have little ability

to reproduce signals below 100Hz to 150Hz. Thus, using a large input capacitor may not increase actual system performance. In this case,

C

R

2

1

f

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I

C

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feedback and is apt to create pops upon device enable. Thus, by minmizing the capacitor size based on necessary low frequency response,

turn-on pops can be minimized.

supply caused by coupling into the output device signal. The noise is from the internal analog reference to the amplifier, which appears as

degraded PSRR and THD+N.

capacitor reduces clicking and popping noise from power on/off and entering and leaving shutdown.

Short Circuit Protection (SCP)

The PAM8007 has short circuit protection circuitry on the outputs that prevents the device from damage when output-to-output and output-to

GND short. When a short circuit is detected on the outputs, the outputs are disabled immediately. If the short was removed, the device

activates again.