HV9925 Supertex, Inc., HV9925 Datasheet - Page 8

• Manufacturer Part Number: HV9925
• Description: Programmable-current Led Lamp Driver Ic With Pwm Dimming
• Manufacturer: Supertex, Inc.

Figure 2. Universal 85-264VAC LED Lamp Driver
Figure 3. 85-135VAC LED Lamp Driver with PWM Dimming
Switching power loss:
P
(33pF • (135V)
P
Minimum duty ratio:
D
(I
O
SWITCH
SWITCH
M
= 20mA, V
= 30V / (135V • √2) ≈ 0.16
2
=
≈ 78mW
O
= 50V) from Example 1
2
10.5µs
+ 135V • √2 x 100mA • 35ns) • 80kHz
80kHz
8
Conduction power loss:
P
Total power dissipation in HV9925:
P
Step 6. Selecting input capacitor C
Output Power = 30V • 50mA = 1.5W
Select C
COND
TOTAL
= 170mW
= 78mW + 170mW = 248mW
IN
3.3µF, 250V.
IN
(
HV9925
)