LDS8711008-T2-300 IXYS [IXYS Corporation], LDS8711008-T2-300 Datasheet

LDS8711008-T2-300

Manufacturer Part Number

LDS8711008-T2-300

Description

High Efficiency 10 LED Driver with No External Schottky

Manufacturer

IXYS [IXYS Corporation]

Datasheet

1.LDS8711008-T2-300.pdf (12 pages)

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LDS8711

FEATURES

 High efficiency boost converter with the input

 250 mV current sense voltage

 Drives one LED string with 10 LEDs in series

 No external Schottky Required (Internal

 0.7 MHz Switching Frequency

 Efficiency greater than 83%

 Smart OneWire™ Interface and PWM LED

 Small External Inductor (10 µH – 33 µH)

 Over voltage, under voltage, over

 Low Shutdown Current (<1µA)

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

APPLICATION

 Color Display Backlight

 Portable Navigation and GPS Receivers

 Smart phones

 Digital Photo Frames

 Portable DVD Players

 Multimedia Phones

DESCRIPTION

The LDS8711 is a fixed frequency current mode

boost converter with internal rectifier and cycle-by-

cycle switch current limit specifically designed to

drive a string of up to 10 White LEDs. It operates

TYPICAL APPLICATION CIRCUIT

*) Patent pending

Characteristics subject to change without notice

voltage range from 2.7 to 5.5 V

up to 32 mA

synchronous rectifier*)

Brightness Control Modes Provide Constant

brightness control

temperature, over current protection

package

LED

High Efficiency 10 LED Driver with No External Schottky

current or constant color temperature

either in PWM or in Smart OneWire™ Interface

mode. The Smart OneWire™ Interface mode allows

set LED current in the range from 0.125 to 32 mA in

256 steps of 0.125 mA each. In PWM mode,

LDS8711 operates with either factory, or customer

preset

connection of the LEDs provides constant current

and subsequently uniform brightness, eliminating the

need for ballast resistors and factory calibration.

Operation at 0.7 MHz allows use of small value

inductor (10 – 33 µH) and external ceramic capacitor

(1 – 2.2 µF).

The use of integrated rectifier makes the efficiency

dependent

parameters: inductor DCR and external capacitor

ESR.

The supply voltage down to 2.7 V for new Li-ion

battery chemistries or two alkaline battery cells

extends the battery life. Under-voltage protection

disables the part when V

The LDS8711 has thermal shutdown set at 150

Above

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 in 8-pin TDFN 2 x 3 mm

package with a max height of 0.8 mm.

this

maximum

value , the

only

LED

two

voltage reaches 2.0 V

current

boost

Doc. No. 8711DS, Rev. N1.0

external

converter

values.

components

Series

stops

Related parts for LDS8711008-T2-300

LDS8711008-T2-300 Summary of contents

Page 1

LDS8711 High Efficiency 10 LED Driver with No External Schottky FEATURES  High efficiency boost converter with the input voltage range from 2.7 to 5.5 V  250 mV current sense voltage  Drives one LED string with 10 LEDs ...

Page 2

LDS8711 ABSOLUTE MAXIMUM RATINGS Parameter V voltage SW, LEDS, Vh voltage OUT EN/SET voltage LED Current Storage Temperature Range Junction Temperature Range 8-pin TDFN package Thermal Resistance Soldering Temperature RECOMMENDED OPERATING CONDITIONS Parameter V IN Ambient Temperature ...

Page 3

LDS8711 Smart OneWire™ TIMING SPECIFICATION Parameter t EN/PWM setup from shutdown to PWM mode SETUP1 t EN/SET setup from shutdown to Smart OneWire™ Interface mode SETUP2 t Bit “zero” positive pulse BO t Bit “one” positive pulse B1 t Low ...

Page 4

LDS8711 TYPICAL CHARACTERISTICS Vin = 3.6V 30mA (10 LEDs per string), C OUT Power Efficiency vs. Input Voltage LED Current vs. PWM Duty Cycle Soft Start Waveforms Ch 1 (yellow) – EN pin (green) – SW ...

Page 5

LDS8711 TYPICAL CHARACTERISTICS Vin = 3.6V 30mA (10 LEDs per string), C OUT Waveforms at PWM LED Current Regulation Ch 1 (yellow) – PWM signal at 1 kHz 5% duty cycle C2 (green) – SW node voltage, Ch ...

Page 6

LDS8711 PIN DESCRIPTION Pin # Name 1 V Input Voltage, connect to battery or power supply IN 2 GND Analog Ground 3 PGND Power Ground 4 SW Switch input; Connect inductor terminal to this pin Output voltage; Connect to the ...

Page 7

LDS8711 BLOCK DIAGRAM BASIC OPERATION At power-up, EN/PWM pin should be logic LOW. The LDS8711 starts operating when EN/PWM pin is asserted logic high. The device becomes enabled and wait for the first pulse that determines mode, at which device ...

Page 8

LDS8711 state equal t (see Figure 1). Every next incoming LO pulse will be recognized as PWM pulse, and maximum LED current will be set equal factory preset value. If PWM frequency is above 5 kHz and duty cycle is ...

Page 9

LDS8711 We recommend C in the range 1.0 – 2.2 µF to OUT achieve better efficiency and driver’s stability. Recommended Layout In active mode, the driver switches internally at a high frequency. We recommend minimize trace length to all external ...

Page 10

LDS8711 PACKAGE DRAWING AND DIMENSIONS 8-PIN TDFN, 2mm x 3mm, 0.5mm PITCH SYMBOL MIN NOM A 0.700 0.750 A1 - 0.000 A2 0.203 Ref. b 0.180 0.230 D 2.950 3.000 D1 1.750 1.800 E 1.950 2.000 E1 1.550 1.600 e ...

Page 11

LDS8711 ORDERING INFORMATION Part Number 1) LDS8711 008-T2 – 300 TDFN - 3mm Notes: 1. Maximum LED current is factory preset at 20, 25 mA. Consult factory if other current values are required. 2. Matte-Tin ...

Page 12

LDS8711 Warranty and Use IXYS CORP. MAKES NO WARRANTY, REPRESENTATION OR GUARANTEE, EXPRESS OR IMPLIED, REGARDING THE SUITABILITY OF ITS PRODUCTS FOR ANY PARTICULAR PURPOSE, NOR THAT THE USE OF ITS PRODUCTS WILL NOT INFRINGE ITS INTELLECTUAL PROPERTY RIGHTS OR ...

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