Datasheet

Application notes - buck conversion LED5000
14/51 Doc ID 023951 Rev 1
Equation 2
Equation 3
where:
Equation 4
S
n
represents the slope of the sensed inductor current, S
e
the slope of the external ramp
(V
PP
peak to peak amplitude) that implements the slope compensation to avoid sub-
harmonic oscillations at duty cycle over 50%
The sampling effect contribution F
H
(s) is:
Equation 5
where:
Equation 6
and
Equation 7
5.3 Error amplifier compensation network
The external compensation network connected at the output of the error amplifier is
dimensioned to stabilize the system depending on the application conditions.
ω
Z
1
ESR C
OUT
⋅
----------------------------------=
ω
P
1
R
LOAD
C
OUT
⋅
----------------------------------------
m
C
1D–()0.5–⋅
LC
OUT
f
SW
⋅⋅
------------------------------------------------+=
m
C
1
S
e
S
n
------
+=
S
e
V
pp
f
SW
⋅=
S
n
V
IN
V
OUT
–
L
------------------------------
R
CS
⋅=
⎝
⎜
⎜
⎜
⎜
⎜
⎜
⎛
F
H
s()
1
1
s
ω
n
Q
P
⋅
---------------------
s
2
ω
n
2
-----++
-------------------------------------------=
ω
n
π f
SW
⋅=
Q
P
1
π m
C
1D–()0.5–⋅[]⋅
----------------------------------------------------------------=