Select R
1 to be approximately 1 kΩ, use a 1% resistor for best stability.
Component values shown are for V
IN = 20 V,
V
OUT = 10 V, I
LOAD = 2 A.
C
IN — 470-µF, 35-V aluminum electrolytic Nichicon
PM Series
C
OUT — 220-µF, 35-V aluminum electrolytic Nichicon
PM Series
D1 — 3.3-A, 60-V Schottky Rectifier, 21DQ06 (international rectifier)
L1 — 47 µH, see
Inductors Selection Procedure
R
1 — 1 kΩ, 1%
R
2 — 7.15 k, 1%
C
FF — 3.3 nF
Typical Values
C
SS — 0.1 µF
C
DELAY — 0.1 µF
R
PULL UP — 4.7 k (use 22 k if V
OUT is ≥ 45 V)
† Resistive divider is required to avoid exceeding maximum rating of 45 V, 3 mA on or into flag pin.
†† Small signal Schottky diode to prevent damage to feedback pin by negative spike when output is shorted (C
FF not being able to discharge immediately will drag feedback pin below ground). Required if V
IN > 40 V.