Pam8302a, Application information – Diodes PAM8302A User Manual
Page 8
PAM8302A
Document number: DSxxxxx Rev. 2 - 5
8 of 14
April 2013
© Diodes Incorporated
PAM8302A
A Product Line of
Diodes Incorporated
Application Information
(cont.)
Power Supply Decoupling (C
S
)
The PAM8302A 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 types of 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, typicall 1.0µF is good, placing it as close as possilbe to the device V
DD
terminal.
For filtering lower frequency noise signals, capacitor of 10µF or larger, closely located to near the audio power amplifier is recommended.
Shutdown Operation
In order to reduce shutdown power consumption, the PAM8032A contains shutdown circuitry for turn to turn off the amplifier. This shutdown
feature turns the amplifier off when a logic low is apllied on the SD pin. By switching the shutdown pin over to GND, the PAM8302A supply
current draw will be minimized inidle mode.
For the best power on/off pop performance, the amplifier should be set in the shutdown mode prior to power on/off operation.
Under Voltage Lock-Out (UVLO)
The PAM8302A incorporates circuitry to detect low on or off voltage. When the supply voltage drops to 2.1V or below, the PAM8302A goes into
a state of shutdown, and the device comes out of its shutdown state to normal operation by reset the power supply or SD pin.
How to Reduce EMI (Electro Magnetic Interference)
A simple solution is to put an additional capacitor 1000μF at power supply terminal for power line coupling if the traces from amplifier to speakers
are short (< 20CM). Most applications require a ferrite bead filter as shown at Figure 1. The ferrite filter depresses EMI of around 1MHz and
higher. When selecting a ferrite bead, choose one with high impedance at high frequencies and low impedance at low frequencies.
Figure 1. Ferrite Bead Filter to Reduce EMI