STA575

14/20

Figure 7. BASH® module SAM351 5.1 with 2 x STA575 (see application note AN1656)

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).

System Description & Operating Rules

SAM351 is a BASH® 5.1 amplifier ( 6 x 100W) implementation utilizing the STA575 Integrated Circuit.

Specifically designed for multi-channel implementation in DVD - HTIB systems, Multi-Media systems, AV Re-

ceivers.

SAM351 is dimensioned to provide the maximum Output Power (THD=10 %) on two channels and instanta-

neously and 1/3 max Pout on the remaining Outputs, or 1/8 of max Pout continuous; this rule is important to

define the main Power Supply size (+50V).

Buck Regulator Description

The function of the buck regulator is to convert efficiently an input voltage to a lower voltage by adjusting the

ratio of the switching transistor's on-time to off-time. The resulting waveform is averaged by the output filter to

recover an analog signal.

In the BASH amplifier this output is in effect split in half by centering it on the audio ground to provide CD+ and

CD- rails.

To avoid the need for a high side driver for the transistor switch in the buck regulator the buck circuit recom-

mended has the switch in the return path. Hence the gate drive circuit (part of the STPB01) is referenced to the

negative return of the main supply that provides power for the buck regulator.

STA575

2 x100Watts

STA575

2 x 100Watts

Buck

Regulator

+50VDC

6 Ohm Loads

Audio

Inputs

STABP01

Controller

Dynamic Power Supply

(CD+ & CD

-)

Signal Power Supply

+/-24V DC / 50

mA

+/-24V DC / 50

mA

Signal Power Supply

Lines

of

Controls

STA575

STA575

2 x 100Watts

2 x 100Watts

Audio

Input

STA575

2 x100Watts

STA575

2 x 100Watts

Buck

Regulator

+50VDC

6 Ohm Loads

Audio

Inputs

STABP01

Controller

Dynamic Power Supply

(CD+ & CD

-)

Signal Power Supply

+/-24V DC / 50

mA

+/-24V DC / 50

mA

Signal Power Supply

Lines

of

Controls

STA575

STA575

2 x 100Watts

2 x 100Watts

Audio

Input