Rev. P05
2
VPN12AD02-FU EVB GUIDE
R
VFBL
VOUT
R
VFBH
GND
VFB
VOUT
Figure 1: VFB Protection Pin
Table 2: Parameter Value Setting
OVP
33.8V
17.6V
Short Protection
13V
6.8V
Jumper JR25
open
short
R
VFBH
(
Ω
)
=R22 =32.2k
=R22//R25 =16.6k
R
VFBL
(
Ω
)
=R23=1.5k
=R23=1.5k
Frequency Setting
The switching frequency can be set from 200 kHz to 400 kHz by an external resistor. Select the
switching frequency with an external resistor according to the following approximate formulas.
46023
F
SW
[kHz]
(
)
1.25
R
FREQ
[k
Ω
]
=
.
Table 3: Parameter Value Setting
Vout
250kHz
350kHz
400kHz
R12 (
Ω
)
46.4k
30k
25.5k
LED Constant Current Setting
V
FBH-FBL
typical value is 150mV. Set the LED current with an external resistor according to the
following approximate formulas.
I
LED
= V
FBH-FBL
R26
Table 4: Parameter Value Setting
ILED
1A
1.5A
2A
R26 (
Ω
)
150m
100m
75m
