AN557 datasheet(49/52 Pages) STMICROELECTRONICS

49 / 52 page

49/52

AN557 APPLICATION NOTE

higher than 1A maintaining an elevated efficiency of the system.

Such outputs must have a good precision and stability and must be protected from short circuiting.

With the application circuit suggested below, one the aime is to satisfy the performance listed above, and

to contributing to the simplification of the power trasformer, both at 50Hz and at high frequency.

It’s important to remember not to exceed the absolute maximum voltage ratings of the device. In this case

the differential voltage applied to the device is the sum of the maximum input voltage (positive) and of that

controlled output negative.

Figure 68.

Figure 69. Circuit for negative output voltage

Linear low drop post regulation

In some application it becomes necessary to generate stable, precise fixed or adjustable output voltages

at high efficiency and with a truly negligible output ripple. Summarizing a regulator that offers the quality

of a linear type of control with the efficiency of a switching regulator. The fig. 70 shows the diagram of a

swithcing preregulator at high efficiency followed by one or more series regulators of the type very "low

drop", or in the case of elevated current, by a discret low drop solution.

L4974A

818

5,6

15,16

15K

220nF

150

µH

3 x

100

µF

EKR

1000

µF

12V<Vi

≤50V

D93IN008A

Vo=18V/3A

56nF

12K

4.7K

SB560

20V

L4974A

818

5,6

15,16

15K

SB560

220nF

100

µH

470

µF

1000

µF

12V<Vi

≤35V

D93IN009

6.2K

4.7K

-12V

AN557 Folha de dados(PDF) 49 Page - STMicroelectronics

AN557 Folha de dados(HTML) 49 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52

Folha de dados Download

Ligação URL