Application ideas

AN1723

20/24

Doc ID 9553 Rev 4

Figure 20.

Buck-boost regulator

7.3

Dual output voltage with auxiliary winding

When two output voltages are required, it is possible to implement a dual output voltage

converter by using a coupled inductor.

During the OFF phase, the current is delivered through the auxiliary winding to the output

This is possible only if the magnetic core has stored sufficient energy. So, to be sure that the

Figure 21.

Dual output voltage with auxiliary winding

7.4

Synchronization example

Two or more devices (up to 6) can be synchronized by simply connecting together the

synchronization pins. In this case, the device with a slightly higher switching frequency value

works as master and those with slightly lower switching frequency values work as

AM11327v1

D03IN1455

8

4

5

1

7

L5973AD

C1

10µF

10V

CERAMIC

C2

10µF

25V

CERAMIC

C5

100µF

16V

VOUT=-12V/

0.6A

VIN = 5V

2.7K

24K

R3

4.7K

C4

22nF

C3

220pF

3

L1 15µH

D1

STPS2L25U

COMP

VCC

OUT

FB

GND

INH

2

6

3.3V

SYNC.

VREF

AM11328v1

D03IN1456

8

4

5

1

7

L5973AD

C1

10µF

25V

CERAMIC

C5

47µF

10V

C4

100µF

10V

VOUT=3.3V/

0.5A

VOUT1=5V/

50mA

VIN = 5V

R3

4.7K

C3

22nF

C2

220pF

3

Lp 22µH

N1/N2=2

D1

STPS25L25U

D2

1N4148

COMP

VCC

OUT

FB

GND

INH

2

6

3.3V

SYNC.

VREF