11

Power Analog Microelectronics, Inc

www.poweranalog.com

MUTE Operation

The MUTE pin is an input for controlling the output

state of the PAM8620. A logic high on this pin

disables the outputs and low enables the outputs.

This pin may be used as a quick disable or enable

of the outputs without a volume fade.

Shutdown Operation

The PAM8620 employs a shutdown operation

mode to reduce supply current to the absolute

minimum level during periods of non-use to save

power. The

input terminal should be held high

during normal operation when the amplifier is in

use. Pulling

low causes the outputs to mute

and the amplifier to enter a low-current state.

should never be left unconnected to prevent the

amplifier from unpredictable operation.

For the best power-off pop performance, the

amplifier should be set in shutdown mode prior to

removing the power supply voltage.

hash on the line, a good low equivalent-series-

resistance (ESR) ceramic capacitor, typically

1µF, is recommended, placing as close as

possible to the device’s VCC lead. To filter lower-

frequency noises, a large aluminum electrolytic

SD

capacitor of 10µF or greater is recommended,

placing near the audio power amplifier. The 10µF

SD

capacitor also serves as a local storage capacitor

SD

f o r s u p p l y i n g c u r r e n t d u r i n g l a r g e s i g n a l

transients on the amplifier outputs.

BSN and BSP Capacitors

The full H-bridge output stages use NMOS

transistors only. They therefore require bootstrap

capacitors for the high side of each output to turn

on correctly. A at least 220nF ceramic capacitor,

rated for at least 25V, must be connected from

each output to its corresponding bootstrap input.

Specifically, one 220nF capacitor must be

connected from xOUTP to xBSP, and another

220nF capacitor from xOUTN to xBSN. It is

recommended to use 1μF BST capacitor to

replace 220nF or lower than 100Hz applications.

VCLAMP Capacitors

To ensure that the maximum gate-to-source

voltage for the NMOS output transistors not

exceeded, a internal regulators are used to clamp

the gate voltage. A 1µF capacitors must be

connected from VCLAMP to ground and must be

rated for at least 25V. The voltages at the

VCLAMP terminals vary with V

and may not be

CC

used to power any other circuitry.

Internal Regulated 5-V Supply (AVDD)

The AVDD terminal is the output of an internally-

generated 5V supply, used for the oscillator,

amplifier,power limit circuitry and logic control

circuitry. It requires a 0.1µF to 1µF capacitor,

placed very close to the pin to Ground to keep the

regulator stable. The regulator may not be used to

power any external circuitry.

decoupling to ensure the output total harmonic

distortion (THD) as low as possible. Power supply

decoupling also prevents oscillations caused by

long lead between the amplifier and the speaker.

The 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

I n t e r n a l 2 . 5 V B i a s G e n e r a t o r C a p a c i t o r

Selection

The internal 2.5V bias generator (V2P5) provides

the internal bias for the preamplifier stage. The

external input capacitors and this internal

reference allow the inputs to be biased within the

o p t i m a l c o m m o n - m o d e r a n g e o f t h e i n p u t

preamplifiers.

The selection of the capacitor value on the V2P5

terminal is critical for achieving the best device

performance. During startup or recovery from

shutdown state, the V2P5 capacitor determines

the rate at which the amplifier starts up. When the

voltage on the V2P5 capacitor equals 0.75 x

V2P5, or 75% of its final value, the device turns on

and the class-D outputs start switching. The

startup time is not critical for the best de-pop

performance since any heard pop sound is the

result of the class-D output switching-on other

than that of the startup time. However, at least a

0.47µF capacitor is recommended for the V2P5

capacitor.

Another function of the V2P5 capacitor is to filter

high frequency noise on the internal 2.5V bias

generator.

Power Supply Decoupling, C

S

The PAM8620 is a high-performance CMOS audio

amplifier that requires adequate power supply

PAM8620

15W Stereo Class-D Audio Power Amplifier with Power Limit

10/2012 Rev1.0

Application Information