Power 2001 Module; Circuit Details; Amplifier; Principle / Benefit Of Super Class G - Philips FW-C390 Service Manual

POWER 2001 Module

(30 - 70W Version)
TABLE OF CONTENTS
Brief Circuit Description.........................................................................11-1
Block Diagram.......................................................................................11-3
Component Layout Mains part.............................................................11-4
Circuit Diagram Mains part ..................................................................11-5
Component Layout Power part ............................................................11-6
Circuit Diagram Power part..................................................................11-7
Partslist .................................................................................................11-8
11-1
stage .9

Circuit details:

Amplifier:

Attention: In the POWER 2001 module the power amplifier IC AN7591 is used as a bridge-amplifier.
Any connection from output to ground will destroy the outpout stages!
• Via the AMP_ON control line, connected to pins 6 (Stby), the power amplifiers are switched on/off by the µP.
High level (approx. 4,5V): power amplifiers switched on
Low level (approx. 0V): power amplifiers switched off
• Super class G - operation
The power amplifiers operate as so-called super class G - amplifiers:
The supply pins 12 (Vcc) are not just connected to one fixed DC-supply as in conventional amplifiers.
Dependent on the output power there are three different DC-voltages supplied to the power amplifiers:
⇒ +C1 (+20V) for low output power
⇒ +B1 (+29V) for medium output power
⇒ +A1 (+41V for high output power

Principle / benefit of Super Class G

Conventional power stage
+A
+C
output signal
activating point +A
Voltage drop on power stage IC
Voltage drop on switching transistor(s)
Benefit - voltage drop on switching transistor(s) reduces total power dissipation
% %
Output power
+A
Power
dissipation
11-1
Class G amplifier Super class G amplifier
+B
+C
output signal
output signal
activating point +A
activating point +B
%
Output power Output power
+A
+C
Power
Power
dissipation dissipation
+A
+B
+C
+A
+B
+C