ACT36X datasheet(10/22 Pages) ACTIVE-SEMI

10 / 22 page

-10-

SEC

AUX

REF

OUTCC

)

(

−

PSR

PSR TM

Active

High Efficiency AC/DC Primary Switching Solutions

ACT366 12V/1000MA CHARGER

Operation and Application

Figure 1 is the schematic of an offline charger

using ACT366YH to provide output power of

12V1000mA. This circuit is a typical flyback

power supply which includes the AC rectified cir-

cuit (BD1,C1, C2),power drive circuit (BD pin,

Q1), secondary rectified circuit (D8, C5,C6) and

the IC control circuit. ACT366YH is a Primary

Side Regulator (PSR) so that the power supply

unit can regulate current and voltage without

Opto-coupler. Pin 6 and Pin 2,4,7 are the VDD

and ground pins to provide power for the IC. Pin

8 is the base drive for the NPN transistor. Pin 1 is

the switching pin. Pin 5 is the feedback pin that

senses the output current and output voltage. Pin

3 is the peak current sense pin. Resistance of

R10 determines the output DC cord compensa-

tion percentage. This circuit can be used as uni-

versal

charger

for

Cell

Phones,PDAs,

MP3,Portable Media Players, Shaver, DSCs, and

Other Portable Devices and Appliances.

Key Component Selection

The maximum output current is decided by for-

mula (1).

Lp is the transformer inductance value, Rcs is the

current sense resistor, which is shown as R9 I

the schematic. Fsw is the switchin frquency,which

design value is 75kHz.

η is the overall system

efficiency, which value is approximately equal to

70%. Voutcc is the output voltage, which setting

is through the flyback voltage of auxiliary winding

and the feedback resistor R5, R6 as shown in

formula (2).

Np/Ns/Naux (96/9/12) must be designed correctly

to ensure it operates in DCM in all conditions. A

design value Voutcc equal to 12V and Ioutcc_min

equal to 1000mA are used to do the design. Ns

and Naux are number of turns of secondary and

auxiliary of the transformer. VSEC_R is the for-

ward voltage drop of the output rectifier diode at

approximately 0.1A bias. The peak current limit is

set by (0.396×0.9)/Rcs.

)

(

)

396

(

OUTCC

Input Voltage

Device

Standby Power

Output Voltage

Power output

Transformer

Topology

85-264VAC

ACT366HY

150mW

12V

12W

EE20

Flyback

Figure 1:

Schematic of Charger

L=45.8mm

W=33.3mm

H=22.4mm

(1)

(2)

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