Datasheet

LT3474/LT3474-1
14
3474fd
APPLICATIONS INFORMATION
Diode Selection
The catch diode (D1 from Figure 1) conducts current only
during switch off time. Average forward current in normal
operation can be calculated from:
I
IVV
V
DAVG
OUT IN OUT
IN
()
=
()
–
The only reason to consider a diode with a larger current
rating than necessary for nominal operation is for the
worst-case condition of shorted output. The diode cur-
rent will then increase to one half the typical peak switch
current.
Peak reverse voltage is equal to the regulator input voltage.
Use a diode with a reverse voltage rating greater than the
input voltage.
If using the PWM mode of the LT3474, select a diode with
low reverse leakage.
Table 4 lists several Schottky diodes and their
manufacturers.
Table 4. Schottky Diodes
PART NUMBER
V
R
(V)
I
AVE
(A)
V
F
at 0.5A
(mV)
V
F
at 1A
(mV)
On Semiconductor
MBR0520L
20 0.5 385
MBR0540 40 0.5 510 620
MBRM120E 20 1 530
MBRM140 40 1 550
Diodes Inc.
B0530W
30 0.5 430
B120 20 1 500
B130 30 1 500
B140 HB 40 1 530
International Rectifi er
10BQ030
30 1 420