PAM8303D
Ultra Low EMI, 3W Filterless
Mono Class-D Audio Power Amplifier
amplifier off when logic low is placed on the SD
pin. By switching the shutdown pin connected to
GND, the PAM8303D supply current draw will be
minimized in idle mode.
PCB Layout Guidelines
Grounding
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.
Under Voltage Lock-out (UVLO)
The PAM8303D incorporates circuitry designed
to detect low supply voltage. When the supply
voltage drops to 2.3V or below, the PAM8303D
goes into a state of shutdown, and the device
comes out of its shutdown state and restore to
normal function only when reset the power
supply or SD pin.
Short Circuit Protection (SCP)
The PAM8303D has short circuit protection
circuitry on the outputs to prevent the device
from damage when output-to-output shorts or
output-to-GND shorts occur. When a short circuit
occurs, the device immediately goes into
shutdown state. Once the short is removed, the
device will be reactivated.
Power Supply Line
Over Temperature Protection (OTP)
As same to the ground, VDD and PVDD need to
be separately connected to the system power
supply. It is recommended that all the trace could
be 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.
Thermal protection on the PAM8303D prevents
the device from damage when the internal die
temperature exceeds 135°C. There is a 15°C
tolerance on this trip point from device to device.
Once the die temperature exceeds the set point,
the device will enter the shutdown state and the
outputs are disabled. This is not a latched fault.
T h e t h e r m a l f a u l t i s c l e a r e d o n c e t h e
temperature of the die decreased by 30°C. This
large hysteresis will prevent motor boating sound
well and the device begins normal operation at
this point with no external system interaction.
Figure 2: Power Line
Components Placement
POP and Click Circuitry
Decoupling capacitors-As previously described,
the high-frequency 1μF decoupling capacitors
should be placed as close to the power supply
terminals (VDD and PVDD) as possible. Large
bulk power supply decoupling capacitors (10μF
or greater) should be placed near the PAM8303D
on the PVDD terminal.
The PAM8303D contains circuitry to minimize
turn-on and turn-off transients or “click and
pops”, where turn-on refers to either power
supply turn-on or device recover from shutdown
mode. When the device is turned on, the
amplifiers are internally muted. An internal
current source ramps up the internal reference
voltage. The device will remain in mute mode
until the reference voltage reach half supply
voltage, 1/2 VDD. As soon as the reference
voltage is stable, the device will begin full
o p e r a t i o n . F o r t h e b e s t p o w e r - o ff p o p
performance, the amplifier should be set in
shutdown mode prior to removing the power
supply voltage.
Input resistors and 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.
Power Analog Microelectronics,Inc
09/2008 Rev 1.4
www.poweranalog.com
13
PAM [ POWER ANALOG MICOELECTRONICS ]
