FB
SW
LM2695
BST
VCC
C6
D1
ISEN
SGND
VIN
SS
RTN
10V
GND
C3
13
11
10
9
6
5
4
2
3
12
GND
C1
C2
2.2
P
F
2.2
P
F
C5
0.022
P
F
0.1
P
F
0.022
P
F
C4
0.1
P
F
L1 100
P
H
RON/SD
R1
200k
R2
7.5k
R3
2.5k
R4
0
C7
22
P
F
C10
0.01
P
F
R6
165k
C9
1000 pF
12V - 30V
Input
V
OUT2
V
OUT1
R6 x C9 =
0.03V
(12V
±
9.83V) x 2300 ns
= 1.66 x 10
-4
R6 x C9 =
'
V
(V
IN
±
V
A
) x t
ON
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Output Ripple Control
•
Calculate the R6 x C9 product as shown in
Equation 3
:
(3)
where t
ON
is the maximum on-time (
≊
2300 ns), V
IN
is the minimum input voltage, and
Δ
V is the desired
ripple amplitude at the R6/C9 junction, 30 mVp-p for this example.
(4)
R6 and C9 are then chosen from standard value components to satisfy the above product. For example,
C9 can be 1000 pF requiring R6 to be 166 k
Ω
. C10 is chosen to be 0.01 µF, large compared to C9. The
circuit as supplied on this EVB is shown in
Figure 2
.
Figure 2. Minimum Ripple Using R6, C9, C10
3
SNVA147A – February 2006 – Revised April 2013
AN-1444 LM2695 Evaluation Board
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