LDS8711 Datasheet, PDF (1/12 Pages) IXYS Corporation – High Efficiency 10 LED Driver with No External Schottky

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 in series
up to 32 mA
 No external Schottky Required (Internal
synchronous rectifier*)
 0.7 MHz Switching Frequency
 Efficiency greater than 83%
 Smart OneWire™ Interface and PWM LED
Brightness Control Modes Provide Constant
I_LED current or constant color temperature
brightness control
 Small External Inductor (10 µH – 33 µH)
 Over voltage, under voltage, over
temperature, over current 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
 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
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 maximum LED current values. Series
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 on only two external components
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 VIN voltage reaches 2.0 V
The LDS8711 has thermal shutdown set at 150 ⁰C.
Above this value , the boost converter stops
switching. The part resumes normal operations when
temperature drops below 130 ⁰C.
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.
*) Patent pending
© 2010 IXYS Corp.
1
Characteristics subject to change without notice
Doc. No. 8711DS, Rev. N1.0