PAM8012 datasheet(9/13 Pages) PAM

9 / 13 page

PAM8012

Mono 2.0W Anti-saturation Class D

Audio Power Amplifier with Power Limit

Power Analog Microelectronics Inc

www.poweranalog.com

06/2012 Rev1.3

Over Temperature Protection (OTP)

POP and Click Circuitry

PCB Layout Guidelines

Grounding

Power Supply Line

Components Placement

Thermal protection on the PAM8012 prevents the

device from damage when the internal die

temperature exceeds 150°C. There is a 15

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 40

. This

large hysteresis will prevent motor boating sound

well and the device begins normal operation at

this point with no external system interaction.

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

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.

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

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.

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

Decoupling capacitors as previously described,

the high-frequency 1 F decoupling capacitors

should be placed as close to the power supply

terminals

as possible. Large

bulk power

supply decoupling capacitors

should be placed near the PAM8012 on the VDD

terminal.

Input resistors and capacitors need to be placed

very close to input pins.

°C

internal

associated

VDD

(10 F or greater)

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.

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