Low voltage power supply

The low-voltage power-supply circuit converts the AC power from the wall receptacle into the DC voltage that the product components use. The product has two low-voltage power-supplies for 110 Volt or 220 Volt input.

Figure 1-5Low voltage power-supply circuit

AC input

 

 

 

DC controller

 

Fuse

 

 

 

 

Noise filter

 

 

 

 

 

Fixing control

 

 

Power switch

Fuse

circuit

 

 

 

 

 

 

 

Noise filter

 

PSTYP100

 

PWRSWON

Zero crossing

 

/ZEROX

 

 

circuit

 

24VRMT

 

 

 

 

 

 

 

 

+24VB

 

 

Switch

+24V

+24VA

 

 

Rectifying

generation

 

 

circuit

 

 

 

circuit

SW3

 

 

 

 

 

Rectifying

 

 

+5VD

 

circuit

Protection circuit

+24VB

+5VC SW1

 

 

 

 

 

 

Switch

Protection circuit

 

 

 

 

SW2

 

 

+5VA

 

 

 

 

 

 

 

PWRSAVE

+3.3VC

 

 

 

 

 

+5V

+3.3V

+3.3VA

 

 

generation

generation

Switch

 

 

 

circuit

circuit

 

 

 

Switch

 

VC5VOFF

 

 

 

 

 

 

Low-voltage power supply

 

 

 

 

 

 

VC3VOFF

 

 

ICB

 

+3.3VB

 

 

 

Switch

 

 

 

 

Formatter

 

 

 

+3.3VA

 

 

 

 

 

+5VB

 

+5VB

 

The low voltage power supply converts the AC power into three DC voltages, which it then subdivides, as described in the following table.

12 Chapter 1 Theory of operation

ENWW