Supertex inc.

does not recommend the use of its products in life support applications, and will not knowingly sell them for use in such applications unless it receives

to the replacement of the devices determined defective due to workmanship. No responsibility is assumed for possible omissions and inaccuracies. Circuitry and

Supertex inc.

1235 Bordeaux Drive, Sunnyvale, CA 94089

Tel: 408-222-8888

www.supertex.com

2

HV9921DB1

Doc.# DSDB-HV9921DB1

A032913

Schematic Diagram

Testing the HV9921DB1

Connect the LED string to the output terminals.

Check the polarity of the LED connection, anode end of the

string should be connected to the positive output, cathode

should be connected to the negative output. Connect the

AC input to the input terminals. Apply the AC voltage at

the input terminals and the LED string should start to glow.

The HV9921DB1 will regulate constant 20mA current in the

LED.

An ammeter can be connected in series with the LED(s) to

measure the output current. The average current reading

may be smaller than 20mA. This is due to the interruptions

in the LED current when the input AC line voltage falls below

the forward voltage of the LED string. The average current

will also vary over the AC line voltage range. Additional

hold-up capacitance can be included across C

interruptions are not desirable.

C

IN

AC Line

85-265V

C

DD

3

HV9921

D1

L1

LED

D2

U1

D3

D4

D5

C

IN2

L

IN

VRD1

F1

C

O

VDD

DRAIN

GND

1

2

Reference Description

Part Number

Manufacturer

C

IN

0.1µF, 400V, metalized polyester film

ECQ-E4104KF

Panasonic

C

IN2

0.033µF, 400V, metalized polyester film

ECQ-E4333KF

Panasonic

C

O

0.01µF, 100V, X7R, MLCC

B37981M1103K054

Epcos

C

DD

0.1µF, 50V, X7R, MLCC

B37987F5104K054

Epcos

L1

68mH, 36mA, mini-drum

RL-5480-3-68000

Renco Electronics

L

IN

2.2mH, 64mA, axial

CTH6-222K

Central Technologies

D1

Diode, UF 600V 1.0A 75ns

MUR160

On Semiconductor

D2-5

Diode, 600V 1.0A

1N4005

Diodes, Inc

VRD1

Surge absorber

ERZ-V05D431

Panasonic

U1

LED Driver IC

HV9921N3-G

Supertex, Inc

F1

Integrated PCB fuse

N/A

N/A

Bill of Materials