L6984 datasheet(13/34 Pages) STMICROELECTRONICS

13 / 34 page

DocID025378 Rev 3

13/34

L6984

Device description

Figure 5. L6984 application circuit

Laplace transformer of the leading network:

Equation 3

where:

Equation 4

The R2, R3 compose the voltage divider. CR3 is calculated as (see Section 4.3.2: COUT

specification and loop stability on page 26 for COUT selection):

Equation 5

3.2

Control loop

The L6984 device is based on a constant on-time control loop with frequency feed-forward

correction over the input range. As a consequence the on-time generator compensates the

input voltage variations in order to keep the switching frequency almost constant over the

input voltage range.

GDIV s



R2 R3

--------------------

1s R3 CR3





R2 R3



R2 R3

-------------------- CR3







-----------------------------------------------------------



 R

3 CR3





--------------------------------------



R2 R3



R2 R3

-------------------- CR3





---------------------------------------------------

fZ fP



CR3

28 10

–

VOUT COUT



----------------------------------



L6984 Arkusz danych(PDF) 13 Page - STMicroelectronics

L6984 Arkusz danych(HTML) 13 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

Arkusz danych Pobierz

Link URL