PAM8620TR datasheet(12/15 Pages) PAM

12 / 15 page

Power Analog Microelectronics, Inc

www.poweranalog.com

Differential Input

Power Limit

The differential input stage of the amplifier

eliminates noises that appear on the two input

lines of the channel. To use the PAM8620 with a

differential source, connect the positive lead of

the audio source to the INP input and the negative

lead from the audio source to the INN input. To

use the PAM8620 with a single-ended source, ac-

ground the INP input through a capacitor equal in

value to the input capacitor on INN and apply the

audio source to the INN input. In a single-ended

input application, the INP input should be ac-

grounded at the audio source other than at the

device input for best noise performance.

Using low-ESR Capacitors

L o w - E S R

c a p a c i t o r s

a r e

r e c o m m e n d e d

throughout this application section. A real (with

respect to ideal) capacitor can be modeled simply

as a resistor in series with an ideal capacitor. The

voltage drop across this resistor minimizes the

beneficial effects of the capacitor in the circuit.

The lower the equivalent value of this resistance

the more the real capacitor behaves as an ideal

capacitor.

Short-circuit Protection

The PAM8620 has short circuit protection circuitry

on the outputs to prevent damage to the device

when output-to-output shorts, output-to-GND

shorts, or output-to-VCCshorts occur. Once a

short-circuit is detected on the outputs, the output

drive is immediately disabled. This is a latched

fault and must be reset by cycling the voltage on

the SD pin to a logic low and back to the logic high

state for normal operation. This will clear the

short-circuit flag and allow for normal operation if

the short was removed. If the short was not

removed, the protection circuitry will again

activate.

Thermal Protection

Thermal protection on the PAM8620 prevents

damage to the device when the internal die

temperature exceeds 160°C. There is a ±15

degree tolerance on this trip point from device to

device. Once the die temperature exceeds the set

thermal point, the device enters into 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 is reduced by 50°C. The

device begins normal operation at this point

without external system intervention.

The voltage at PL pin can used to limit the power

to levels below that which is possible based on

the supply rail. Add a resistor from PL to ground to

set the voltage at the PLIMIT pin. An external

reference may also be used if tighter tolerance is

required. Also add a 1uF capacitor fromPL pin to

ground. The PLIMIT circuit sets a limit on the

output peak-to-peak voltage. The gain of class D

amplifier will automatic reduced if the output

power higher than setting value to make output

power less than limited value and also provide

good sound quality.

The output power

vs PL pin resistor value as

below.

VCC=24V,Rload=8

VCC=12V,Rload=8

PAM8620

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

10/2012 Rev1.0

R(Ω)

PL (V)

PL(W)

R(Ω)

PL (V)

PL(W)

56K

0.62

3.2

110K

1.08

9.6

62K

0.68

3.8

120K

1.15

11.0

68K

0.73

4.4

130K

1.23

12.4

75K

0.79

5.2

150K

1.36

15.5

82K

0.86

6.1

160K

1.43

17.0

91K

0.93

7.1

180K

1.55

19.9

100K

1.00

8.2

200K

1.66

22.9

Hard Clip

Soft Clip

PAM Plimit

R(Ω)

PL (V)

PL(W)

R(Ω)

PL (V)

PL(W)

56K

0.61

3.1

100K

0.99

8.1

62K

0.67

3.7

110K

1.07

9.0

68K

0.73

4.3

120K

1.15

9.6

75K

0.79

5.1

130K

1.22

10.0

82K

0.85

6.0

140K

1.36

10.7

91K

0.92

7.0

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