PAM8012 Datasheet, PDF (9/13 Pages) Power Analog Micoelectronics – Mono 2.0WAnti-saturation Class D Audio Power Amplifier with Power Limit

PAM8012
Mono 2.0W Anti-saturation Class D
Audio Power Amplifier with Power Limit
Over Temperature Protection (OTP)
Thermal protection on the PAM8012 prevents the
device from damage when the internal die
temperature exceeds 150°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.
The thermal fault is cleared once the
temperature of the die decreased by 40°C. This
large hysteresis will prevent motor boating sound
well and the device begins normal operation at
this point with no external system interaction.
POP and Click Circuitry
The PAM8012 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 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
Grounding
It is recommended to use plane grounding. 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
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.
Figure 2: Power Line
Components Placement
Decoupling capacitors as previously described,
the high-frequency 1 μF decoupling capacitors
should be placed as close to the power supply
terminals VDD as possible. Large bulk power
supply decoupling capacitors (10 μF or greater)
should be placed near the PAM8012 on the VDD
terminal.
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
www.poweranalog.com
9
06/2012 Rev1.3