L7986 STMicroelectronics, L7986 Datasheet - Page 21

• Manufacturer Part Number: L7986
• Description: 3A step-down switching regulator
• Manufacturer: STMicroelectronics

Specifications of L7986

• Low Dropout Operation: 100% duty cycle

L7986
Equation 23
Figure 10. Type III compensation network
In
and the open-loop gain (G
Figure 11. Open-loop gain: module Bode diagram
The guidelines for positioning the poles and the zeroes and for calculating the component
values can be summarized as follows:
1.
2.
Figure 11
Choose a value for R
Choose a gain (R
the Bode diagram of the PWM and LC filter transfer function (G
f
P0
4
/R
=
0
1
1
LOOP
) in order to have the required bandwidth (BW), that means:
,
, usually between 1 kΩ and 5kΩ.
Doc ID 022450 Rev 1
f
(f)=G
P1
=
----------------------------- -
2π R
PW0
⋅
1
· G
3
⋅
C
LC
3
(f) · G
,
f
P2
TYPEIII
=
------------------------------------------- -
2π R
(f)) are drawn.
⋅
4
1
⋅
------------------- -
C
C
4
4
Application information
+
⋅
C
C
5
5
PW0
· G
LC
(f))
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