PAM8406

Document number: DSxxxxx Rev. 1 - 0

10 of 14

www.diodes.com

March 2013

© Diodes Incorporated

PAM8406

A Product Line of

Diodes Incorporated

Power Supply Decoupling

The PAM8406 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 targeting to different types of noise on the power supply leads. For higher frequency transients, spikes, or digital hash on the line,

terminal. For filtering lower frequency noise signals, a large capacitor of 20μF (ceramic) or greater is recommended, placing it near the audio

power amplifier.

Large input capacitors are both expensive and space hungry for portable designs. Clearly, a certain 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, input

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

turn-on pops can be minimized.

supply coupling into the output drive signal. This noise is from the internal analog reference to the amplifier, which appears as degraded PSRR

and THD+N.

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

Under Voltage Lock-Out (UVLO)

The PAM8406 incorporates circuitry designed to detect low supply voltage. When the supply voltage drops to 2.0V or below, the PAM8406

Short Circuit Protection (SCP)

The PAM8406 has short circuit protection circuitry on the outputs to prevent damage to the device when output-to-output or output-to-GND short

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

again.

Over Temperature Protection

Thermal protection on the PAM8406 prevents the device from damage when the internal die temperature exceeds +150°C. There is a 15 degree

tolerance on this trip point from device to device. Once the die temperature exceeds the thermal set point, the device outputs are disabled. This

is not a latched fault. The thermal fault is cleared once the temperature of the die is reduced by 30°C. This large hysteresis will prevent motor

boating sound well and the device begins normal operation at this point without external system intervention.