AN1643 APPLICATION NOTE

6/7

Power - On-Off sequences:

In order to avoid damages to the SAM261 board it is important to follow these sequences:

At Power-On apply in the first the Auxiliary Power Supply (±24V) and after the Main Power Supply

(+50V), in this condition the system is in "Mute state" and it can move in "play state" with the switch present

on the pcb.

At Power-Off is better to bring the SAM module in "Mute state" and after that to follow this order: switch-

off the Main Supply Voltage (+50V) and subsequently the Auxiliary Power Supply. (±24V).

Figure 5. Thd +noise vs. Output Power Satellite channels

Figure 6. Thd +noise vs. Output Power Subwoofer channel

Dis tortion vs . Out put P ower

TDA 7448 + S AM 261

Out put 1

Rl= 8 O hm

s olid Cy an line f= 1 k hz

das h Green line = 10 k hz

dot Red line = 100 Hz

0.01

10

0.02

0.05

0.1

0.2

0.5

1

2

5

%

100m

60

200m

500m

1

2

5

10

20

W

Dis tortion vs. Output P ower

TDA7448 + SAM 261

Output s ubwoofer

Rl= 4 Ohm

solid line Green f= 1 khz

dot line yellow = 100 Hz

0.01

10

0.02

0.05

0.1

0.2

0.5

1

2

5

%

600m

100

12

5

10

20

50

W