ZXSC310 datasheet(6/14 Pages) ZETEX

6 / 14 page

REFERENCE DESIGNS

Three typical LED driving applications are shown.

Firstly a typical LCD backlight circuit, then maximum

brightness LED driving solution and lastly an

optimised battery life LED driving solution.

This application shows the ZXSC310 in a typical LCD

backlight application for Digital Still Cameras and

PDA’s. The input voltage for these backlight circuits are

usually fixed from the main system power, typically

3.3V or 5V. The LED’s are connected serially so that the

light is distributed uniformly in each LED. The current

provided to the LED’s can either be pulsed or DC. The

DC current is programmable via a sense resistor,

RSENSE, and is set to an optimum LED current of 20mA

for the reference designs. DC current is achieved by

adding a Schottky rectifying diode and an output

capacitor, as shown in the reference design below.

ZXSC310

PROVISIONAL ISSUE A - SEPTEMBER 2001

VIN

V CC

= 3.3V / 5V

DRIVE

I SENSE

Gnd

TDN

LCD backlight circuit

Ref

Value

Part Number

Manufacture

Comments

N/A

ZXSC310E5

Zetex Plc

Single cell converter, SOT23-5

N/A

FMMT618

Zetex Plc

Low V

CE(sat) NPN, SOT23

N/A

ZHCS1000

Zetex Plc

1A Schottky diode, SOT23

2.2 F

Generic

Various

0805 Size

150m

Generic

Various

1206 Size

250m

Generic

Various

1206 Size

68µH

Surface mount inductor

Materials list

6Used for 3.3V input, ILED set to 20mA 10%.

7Used for 5V input, ILED to 20mA 10%.

8See Application section.

(Notes)

ZXSC310 Datasheet(PDF) 6 Page - Zetex Semiconductors

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