STA530

2/17

DESCRIPTION (continued)

In fact it's permits to build a BASH® architecture amplifier adding only few external components and a variable

Buck regulator tracking the audio signal. Notice that normally only one Buck regulator is used to supply a mul-

tichannel amplifiers system , therefore most of the functions implemented in the circuit have a summing output

pin.

The signal circuits are biased by fixed negative and positive voltages referred to Ground. Instead the final stag-

es of the output amplifiers are supplied by two external voltages that are following the audio signal . In this way

the headroom for the output transistors is kept at minimum level to obtain a high efficiency power amplifier.

The circuit contains all the blocks to build a configurable four channel amplifier.

The tracking signal for the external Buck regulator is generated from the Absolute Value Block (AVB) that rec-

tifies the audio signal. The outputs of these blocks are decoupled by a diode to permit an easy sum of this signal

for the multichannel application. The gain of the stage AVB is equal to 70 (+36.9 dB). A sophisticated circuit

performs the output transistor power detector that , with the buck regulator, reduces the power supply voltage .

Moreover, a maximum current output limiting and the over temperature sensor have been added to protect the

circuit itself. The external voltage applied to the STBY/MUTE pin forces the two amplifiers in the proper condi-

tion to guarantee a silent turn-on and turn-off.

ABSOLUTE MAXIMUM RATINGS

THERMAL DATA

Symbol

Parameter

Value

Unit

Positive supply voltage referred to pin 14 (GND)

27

V

Negative supply voltage referred to pin 14 (GND)

-27

V

Positive supply voltage tracking rail referred to pin 14 (GND)

20

V

-0.3

V

Negative supply voltage tracking rail referred to pin 14 (GND)

-20

V

Pin 11, 10, 9, 8 Negative & Positive maximum voltage referred to

GND (pin 14)

-25 to +25

V

Pin 17, 18, 19, 20 Negative & Positive maximum voltage referred

to GND (pin 14)

-25 to +25

V

Pin 12 maximum input current (Internal voltage clamp at 5V)

500

µA

MUTE

Pin 12 negative maximum voltage referred to GND (pin 14)

-0.5

V

Symbol

Parameter

Value

Unit

Max Junction temperature

150

°C

1

°C/W