9

Power Supply Specifications

+Bus and -Bus

The voltage necessary to achieve full power is

±110V. In an

unregulated supply, the no load voltage will be significantly

higher. The MOSFETs used in the amplifier support the

differential voltage between the buses. That is if the +/-Bus

are 125V, then each MOSFET has to support 250V. The

breakdown of the MOSFETS is 275V. Care must be take to

ensure that under no load, high line conditions this

breakdown voltage is not exceeded. Doing so may damage

the amplifier.

This limitation makes it difficult to achieve full power from an

unregulated power supply. The output impedance of the

transformer has to be very low and the size of the bulk

capacitance must be large. A better solution is to use a

switching power supply. This allows the amplifier to be used

to its full potential. With an unregulated power supply, 500W

is the maximum power. The amplifier will still be able to

provide 600W transient RMS power.

While not shown in the power supply diagram, high

frequency ceramic caps (0.1

µF) should be placed in parallel

with the electrolytic capacitors for the +/-12V bias and

12VFLT. This additional filtering will improve the performance

of the amplifier.

+12V and -12V

Each supply draws approximately 40mA. Regulation is

required. For best results make sure that the rectified

secondary voltage at minimum line voltage is greater than

the dropout voltage of the regulator. Any 100mA, 12V, linear

regulator can be used.

12VFLT

This voltage is needed to drive the gates of the MOSFETs.

The current required is on the order of 400mA. This voltage

should also be regulated. The current is high enough that a

1A regulator with heatsinking is required. This supply is

referenced to -Bus. Do not reference this supply to

ground as the amp will be damaged.

NOTE: In applications that use multiple modules, power supplies

can be shared as long as the currents of each supply is scaled

accordingly.

The voltages on +/-Bus are dangerous. Be careful. Do not

touch the components inside the shield when power is

applied. Make sure the bulk capacitance in the power supply

is discharged before disconnecting or connecting the edge

connector. Don’t touch uninsulated speaker wires when the

amp is running at high powers. Diodes D1- D4 are for

required for safety. Use them.

Power Supply For the HCA600ACREF

WARNING: High voltage secondary.

NOTES:

7. D1, D2 are 200V, 3A diodes. These will blow both fuses if either MOSFET in the power amplifier fails short.

8. D3, D4 are 200V, 1A diodes that return energy to the supply if a fuse blows.

FIGURE 6.

+

-

12VFLT

AC INPUT

12,000

µF

12,000

µF

470

µF

1,000

µF

1kVA TRANSFORMER

125V NO LOAD

12V

REG

100

µF

+12V

-12V

100

µF

19V NO LOAD

19V NO LOAD

92VAC

92VAC

13.6VAC

15A

1A

15A

STAR GROUND

160V

-125V NO LOAD

PINS 1, 4

PINS 12, 13

PINS 15, 16

PIN 9

PIN 10

PINS 11, 14, 18

PGND

-BUS

+BUS

AGND

PIN 17

12VFLT

-12V

+12V

D1

D2

D3

D4

+

-

13.6VAC

13.6VAC

19V NO LOAD

470

µF

16V

16V

35V

100

µF

160V

35V

25V

35V

REG

-12V

12V

REG

HCA600ACREF