LDS8726

© 2010 IXYS Corp.

1

Doc. No. 8726DS, Rev. N1.0

Characteristics subject to change without notice

49 WLED Driver with Boost Converter

FEATURES

 High efficiency boost converter with the input

voltage range from 2.7 to 5.5 V

 No external Schottky Required (Internal

synchronous rectifier*)

 250 mV current sense voltage

 Drives up to 7 LEDs per string with up to 49

LED in 7 strings at 25 mA

 1 MHz Switching Frequency

 Efficiency greater than 83%

 PWM LED Dimming Control Mode

 Over-voltage, under-voltage, over-current,

and over-temperature protection

 Low Shutdown Current (<1µA)

 Available in 2 x 3 x 0.8 mm 8-pin TDFN

package

APPLICATION

 Color Display Backlight

 Portable Navigation and GPS Receivers

 Smart phones

 Digital Photo Frames

 Portable DVD Players, Notebooks

DESCRIPTION

The LDS8726 is a fixed frequency current mode

boost converter with internal synchronous rectifier

and cycle-by-cycle switch current limit specifically

designed to drive matrix of LEDs in respect with the

Table 1. Operation at 1 MHz allows use of small

value low profile inductor (10 – 33 µH) and 1 µF 50 V

ceramic capacitor.

The use of integrated synchronous rectifier makes

the

efficiency dependent

on

only inductor DC

resistance. Under-voltage protection disables the part

The LDS8726 has thermal shutdown set at 150

Above

this

value ,

the

boost

converter

stops

switching. The part resumes normal operations when

temperature drops below 130

The over-current protection provides cycle-by-cycle

current limit.

The internal output over-voltage protection prevents

damage in the case of a faulty LED disconnect.

The PWM control ensures brightness adjustment with

a frequency from 100 Hz up to 30 KHz.

The EN/PWM logic input functions as a chip enable

and LED current PWM contol pin.

The device is available in 8-pin TDFN 2 x 3 mm

package with a max height of 0.8 mm.

Table 1 Matrix configuration for LDS8726

Number of

strings

Number of

LED per string

String

Current

max, mA,

1 - 5

7

30

2.7

6

7

30

3.3

6

7

25

2.7

7

7

25

3.1

7

6

25

2.7

8

5

25

2.7

TYPICAL APPLICATION CIRCUIT

*) Patent pending