HV9925SG-G Supertex, HV9925SG-G Datasheet - Page 7

• Manufacturer Part Number: HV9925SG-G
• Description: LED Drivers Programmable Current LED Lamp
• Manufacturer: Supertex

Specifications of HV9925SG-G

• Operating Supply Voltage: 20 V to 400 V
• Maximum Supply Current: 500 uA
• Maximum Power Dissipation: 800 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC N EP
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Step 1. Calculating L1.
The output voltage V
(1) assuming a 30% peak-to-peak ripple.
L1 = (41V • 10.5µs) / (0.3 • 20mA) = 72mH
Select L1 68mH, I=30mA. Typical SRF = 170KHz. Calculate
the coil capacitance.
Step 2. Selecting D1
Usually, the reverse recovery characteristics of ultra-
fast rectifiers at I
manufacturer’s data books. The designer may want to
experiment with different diodes to achieve the best result.
Select D1 MUR160 with V
= 100mA) and C
Step 3. Calculate total parasitic capacitance using (3):
CP = 5pF + 5pF +13pF + 8pF = 31pF
Step 4. Calculating the leading edge spike duration using
(4) and (5):
Step 5. Estimating power dissipation in HV9925 at 264VAC
using (8) and (10)
Switching power loss:
P
Minimum duty ratio:
DM = (0.71 • 41V) / 264V ≈ 0.11
Conduction power loss:
P
0.20 • (20mA)
SWITCH
COND
=
≈ 130mW
10.5µs
2
• 210Ω + 0.63 • 200µA • 264V ≈ 50mW
J
≈ 8pF (V
F
= 20~50mA are not provided in the
O
68
= 10
R
F
>50V).
= 600V, t
·
V
F
≈ 41V (max.). Use equation
●
rr
1235 Bordeaux Drive, Sunnyvale, CA 94089
≈ 20ns (I
F
= 20mA, I
RR
7
Total power dissipation at V
P
Step 6. Selecting input capacitor C
Output Power = 41V • 20mA = 820mW
Select C
Metalized Polyester Film).
Design Example 2
Let us now design a PWM-dimmable LED lamp driver using
the HV9925:
Input:
Output Current: 50mA
Load:
The schematic diagram of the LED driver is shown in Fig.3.
We will use an aluminum electrolytic capacitor for C
to prevent interruptions of the LED current at zero crossings
of the input voltage. As a “rule of thumb”, 2~3μF per each
watt of the input power is required for C
Step 1. Calculating L1.
The output voltage V
(1) assuming a 30% peak-to-peak ripple.
L1 = (30V • 10.5µs) / (0.3 • 50mA) = 21mH
Select L1 22mH, I = 60mA. Typical SRF = 270KHz. Calculate
the coil capacitance.
Step 2. Selecting D1
Select D1 ES1G with V
Step 3. Calculating total parasitic capacitance using (3):
CP = 5pF + 5pF +15pF + 8pF = 33pF
Step 4. Calculating the leading edge spike duration using
(4) and (5):
Step 5. Estimating power dissipation in HV9925 at 135VAC
using (6), (7) and (9)
TOTAL
= 130mW + 50mW = 180mW
IN
●
ECQ-E4104KF by Panasonic (0.1µF, 400V,
Tel: [phone]
Universal AC, 85-135VAC
String of 12 LED (Power TOPLED
OSRAM, V
33pF
O
= 12 · V
R
= 400V, t
F
AC(max)
33ns 102ns
●
= 2.5V max. each)
F
www.supertex.com
= 30V (max.). Use equation
:
rr
IN
≈ 35ns and C
IN
in this case.
HV9925
J
< 8.0pF.
IN
in order
®
by