10

Mute Operation

Shutdown Operation

The

pin is an input for controlling the

output state of the PAM8603M. A logic low on this

pin disables the outputs, and a logic high enables

the outputs. This pin may be used as a quick

disable or enable of the outputs without a volume

fade. Quiescent current is listed in the electrical

characteristic table. The

pin can be left

floating due to the

pull-up .

In order to reduce power consumption while not in

use, the PAM8603M contains shutdown circuitry

to turn off the amplifier's bias circuitry. The

amplifier is turned off when logic low is placed on

the

pin. By switching the

pin

connected to GND, the PAM8603M supply current

draw will be minimized in idle mode. The

pin can be left floating due to the

pull-up.

MUTE

MUTE

SHDN

SHDN

SHDN

internal

For better power-off pop performance, the

amplifier should be placed in the mute mode prior

to removing the power supply.

internal

Power supply

decoupling affects low frequency response.

Optimum decoupling is achieved by using two

capacitors of different types that target different

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, typically 1.0 F, placed

as close as possible to the device VDD terminal

works best.

10μF (ceramic)

The PAM8603M incorporates circuitry to detect

low supply voltage. When the supply voltage

drops to 1.8V or below, the PAM8603M outputs

are disable. The device resumes to normal

functional once V

2.0V.

The PAM8603M has short circuit protection

circuitry on the outputs to prevent the device from

damage when output-to-output or output-to-GND

short. When a short circuit is detected on the

outputs, the outputs are disable immediately. If

the short was removed, the device activates

again.

μ

≥

Under Voltage Lock-out (UVLO)

Short Circuit Protection (SCP)

DD

Power Supply Decoupling

Input Capacitor (C )

Analog Reference Bypass Capacitor (C

)

The PAM8603M is a high performance CMOS

audio amplifier that requires adequate power

supply decoupling to ensure the output THD and

PSRR a s low as possible.

For filtering lower-frequency noise

signals, a large capacitor of

or

greater placed near the audio power amplifier is

recommended.

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 attenu ation. 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 perfor mance. In this

case, input capacitor (C ) and input resistance (R )

of the amplifier form a high-pass filter with the

corner frequency determined equation below,

In addition to system cost and size, click and pop

perfor mance is affected by the size of the input

coupling capacitor, C . A larger input coupling

capacitor requires more charge to reach its

quiescent DC voltage (nominally 1/2 V ). This

charge comes from the internal circuit via the

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.

The Analog Reference Bypass Capacitor (C

) is

the most critical capacitor and serves several

important functions. During start-up or recovery

from shutdown mode, C

determines the rate at

which the amplifier starts up. The second function

is to reduce noise produced by the power supply

coupling in the output drive signal. This noise is

from the internal analog reference to the amplifier

which appears as degraded PSRR and THD+N.

A ceramic bypass capacitor (C

) of 0.47μF to

1.0μF is recommended for the best THD and noise

performance. Increasing the bypass capacitor

reduces clicking and popping noise from power

on/off and entering and leaving shutdown.

i

BYP

ii

i

DD

BYP

BYP

BYP

Application Information

C

ii

1

f=

2πR C

10/2008 Rev 1.0

,

Power Analog Microelectronics Inc

www.poweranalog.com

PAM8603M

3W Filterless Stereo Class-D Audio Amplifier with DC Volume Control