HV9903 查看數據表（PDF） - Supertex Inc

零件编号

产品描述 (功能)

生产厂家

HV9903

White LED Driver

Supertex Inc 

HHVV99990033

Component selection is similar to the Li-ion battery

application with the exception of the inductor and CDD

capacitor. Since high current is no longer being

drawn from VDD, CDD may be lowered to around 10nF.

CIN should be 1µF. In selecting the inductor, use the

following graphs.

Inductor Value for 1.8V Operation

100 H

10 H

ILED

20mA

25mA

30mA

35mA

40mA

1H

5V

Select the next lower standard value,

taking inductor tolerance into account.

ILED

5mA

10V

15V

20V

VLED-STRING + (ILED · 5? ) + VD

VLED-STRING + (ILED -5Ω) +VD

25V

10mA

15mA

Inductor Rating for 1.8V Operation

40mA 35mA

1A

Exceeds max recommended SW current

30mA

25mA

100mA

20mA

15mA

10mA

5mA

ILED

Apply correction factor and select an

inductor with an equal or higher rating.

10mA

5V

10V

15V

20V

25V

VLED-STRING + (ILED · 5? ) + VD

VLED-STRING + (ILED -5Ω) +VD

Don’t forget to apply the correction factor and confirm

that the inductor is not saturating and the driver is

operating in discontinuous mode, as outlined earlier.

Board Layout

Since high frequencies are involved, PCB layout is

critical. To minimize parasitic inductance and radiated

EMI, the loop area of the high frequency paths must

be kept to a minimum. Second, try to keep the two

loop areas as concentric as possible. Lastly, make

traces as short and wide as possible. To avoid LED

current errors, keep the RSET ground connection

separate from high current ground paths and connect

directly to pin 2.

The following schematic depicts the high frequency

paths and their enclosed areas.

L

D

COUT

Keep these

areas small

SW closed

SW open

CDD HV9903

1 SW

VDD 6

2 GND SHDN 5

3 LED

RSET 4

Keep ground

connection seperate

and direct to pin 2

VDD

Shutdown

Fault

RSET

The following PCB layout is recommended.

L

D

COUT

VDD

CDD

HV9903 SHDN

GND

RSET

9

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