W-6237 Datasheet, PDF (8/13 Pages) Copal Electronics – High Voltage CMOS Boost

W-6237
Application Information
External Component Selection
Capacitors
The W-6237 only requires small ceramic capacitors of
4.7 F on the input and 0.22 F on the output. Under normal
condition, a 4.7 F input capacitor is sufficient. For
applications with higher output power, a larger input
capacitor of 10 F may be appropriate. X5R and X7R
capacitor types are ideal due to their stability across
temperature range.
Inductor
A 33 H inductor is recommended for most of the
W-6237 applications. In cases where the efficiency is
critical, inductances with lower series resistance are
preferred. Inductors with current rating of 300 mA or higher
are recommended for most applications. Sumida
CDRH3D16ï330 33 H inductor has a rated current of
320 mA and a series resistance (D.C.R.) of 520 m typical.
Schottky Diode
The current rating of the Schottky diode must exceed the
peak current flowing through it. The Schottky diode
performance is rated in terms of its forward voltage at a
given current. In order to achieve the best efficiency, this
forward voltage should be as low as possible. The response
time is also critical since the driver is operating at 1 MHz.
Central Semiconductor Schottky diode CMDSH05ï4
(500 mA rated) is recommended for most applications.
LED Current Setting
The LED current is set by the external resistor R₁
connected between the feedback pin (FB) and ground. The
formula below gives the relationship between the resistor
and the current:
0.3 V
R_{1 LED} current
Table 5. RESISTOR R₁ AND LED CURRENT
LED Current (mA)
R₁ ( )
5
60
10
30
15
20
20
15
25
12
30
10
8