Philips MC-70 - POWER 2001 Module; Circuit Details; Amplifier; Class

stage .5
POWER 2001 Module
(40W Super G -Version)
11-111-1
TABLE OF CONTENTS
Brief Circuit Description ....................................................................11-1
Block Diagram ..................................................................................11-3
Mains Board
Component Layout .....................................................................11-4
Circuit Diagram ...........................................................................11-5
Combi Board
Component Layout copperside ................................................11-6
Circuit Diagram Source Selector part .......................................11-7
Component Layout componentside .........................................11-8
Circuit Diagram Amplifier part ...................................................11-9
Regulator Board
Component Layout copperside ..............................................11-10
Circuit Diagram Source Selector part .....................................11-11
Component Layout componentside .......................................11-12
Partslist...........................................................................................11-13
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:
⇒ +C (+17V) for low output power
⇒ +B (+23V) for medium output power
⇒ +A (+35V) for high output power
Principle / benefit of Super Class G
Conventional power stage Class G amplifier Super class G amplifier
output signal
output signal
output signal
+A
+B
+C +C
+A
+B
+C
Voltage drop on power stage IC
Voltage drop on switching transistor(s)
Benefit - voltage drop on switching transistor(s) reduces total power dissipation
activating point +A activating point +B
activating point +A
t
Power
Power
dissipation
t
Power
Power
dissipation
t
Power
Power
dissipation
Output power
Benefit
Output power
%% %
Output power
Benefit
+C
+A
+A
+C
+A
+B