7

NR092005

HV9921/HV9922/HV9923

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

are not provided in the

manufacturer’s data books. The designer may want to

experiment with different diodes to achieve the best result.

Select D1 MUR160 with V

≈ 20ns (I

I

Step 3. Calculating total parasitic capacitance using (3)

Step 4. Calculating the leading edge spike duration using

(4), (5)

Step 5. Estimating power dissipation in HV9921 at 264VAC

using (8) and (10)

Let us assume that the overall efficiency

η = 0.7.

Switching power loss:

P

Minimum duty ratio:

Conduction power loss:

Total power dissipation in HV9921:

Step 6. Selecting input capacitor C

IN

Select C

IN

ECQ-E4104KF by Panasonic (0.1

µF, 400V,

Metalized Polyester Film).

()

(

)

L

22

11

C13 pF

L1 2

SRF

68mH

2

170KHz

ππ

==

≈

⋅⋅

⋅⋅

P

C

5 pF 5 pF 13 pF 8 pF

31pF

=+

+

+

=

()

SPIKE

BLANK MIN

264V

2 31pF

T

20ns 136ns T

100mA

⋅⋅

=+

≈

<

()

..

SWITCH

141V

P

264V 31pF 2 100mA 20ns 264V

210 5 s

07

µ

⎛⎞

≈⋅

+ ⋅

⋅

−

⎜⎟

⋅

⎝⎠

/( .

)

.

m

D

41V 07 264V

2

0 16

=⋅

⋅

≈

()

..

2

COND

P

0 25 20mA

210

0 63 200 A 264V

55mW

Ωµ

=⋅

⋅

+

⋅

⋅

≈

TOTAL

P

120mW

55mW

175mW

=+

=

Output Power 41V 20mA 820mW

=⋅

=

Figure 2. Universal 85-264VAC LED Lamp Driver

C

IN

AC Line

85-264V

C

DD

1

3

2

HV9921/22/23

D1

L1

LED

D2

U1

D3

D4

D5

C

IN2

L

IN

VRD1

F1

C

O

DRAIN

GND