ACT30

Rev 5, 05-Jun-09

Active-Semi

Innovative Power

TM

- 7 -

www.active-semi.com

Copyright © 2009 Active-Semi, Inc.

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F1

AC1

AC2

IC1

ACT30A

1

D1

T1

3

GND

5V/750mA

C8

R12

R11

C9

R13

IC3

TL431

Q2

R16

R15

R14

L2

R9

R10

C7

D8

R18

C10

C19

D5

R6

R5

D6

C4

R3

D7

R7

Z1

IC2B Opto

C20

C6

C5

C3

R2B

R2A

C1

C2

R1

L1

D2

D3

D4

IC2A

Opto

R8

EE-16

Figure 5:

A 3.75W Charger Using ACT30A in Combination with TL431

APPLICATIONS INFORMATION

External Power Transistor

The ACT30 allows a low-cost high voltage power

NPN transistor such as ‘13003 or ‘13002 to be used

safely in a flyback configuration. The required

output load is at least 600V to 700V. As seen in

Figure 4, the breakdown voltage of an NPN is

significantly improved when it is driven at its emitter.

Thus, the ACT30 and ’13002 or ‘13003 combination

meet the necessary breakdown safety requirement

even though RCC circuits using ‘13002 or ‘13003

do not. Table 1 lists the breakdown voltage of some

transistors appropriate for use with the ACT30.

Table 1:

Recommended Power Transistor List

Figure 4:

NPN Reverse Bias Safe Operation Area

The power dissipated in the NPN transistor is equal

to the collector current times the collector-emitter

voltage. As a result, the transistor must always be

in saturation when turned on to prevent excessive

power dissipation. Select an NPN transistor with

drive resistor (R2 in Figure 1) low enough to ensure

that the transistor easily saturates.

Base-Drive

Safe Region

(RCC)

Emitter-Drive

Safe Region

(ACT30)

DEVICE

MJE13002 600V 300V 1.5A

8

TO-126

MJE13003,

KSE13003

700V 400V 1.5A

8

TO-126

STX13003

700V 400V

1A

8

TO-92