LDS8711 IXYS, LDS8711 Datasheet

IC INTERFACE

LDS8711

Manufacturer Part Number
LDS8711
Description
IC INTERFACE
Manufacturer
IXYS
Datasheet

Specifications of LDS8711

Constant Current
*
Constant Voltage
*
Topology
*
Number Of Outputs
*
Internal Driver
*
Type - Primary
*
Type - Secondary
*
Frequency
*
Voltage - Supply
*
Voltage - Output
*
Mounting Type
Surface Mount
Package / Case
8-WFDFN Exposed Pad
Operating Temperature
*
Current - Output / Channel
*
Operating Supply Voltage
2.7 V to 5.5 V
Maximum Supply Current
3 mA
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
Minimum Operating Temperature
- 40 C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
LDS8711TR
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
© 2010 IXYS Corp.
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
I
brightness control
temperature, over current protection
package
LED
High Efficiency 10 LED Driver with No External Schottky
current or constant color temperature
1
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
on
value , the
only
LED
IN
two
voltage reaches 2.0 V
current
boost
Doc. No. 8711DS, Rev. N1.0
0
external
C.
converter
values.
components
Series
stops
0
C.

Related parts for LDS8711

LDS8711 Summary of contents

Page 1

... 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 voltage reaches 2 The LDS8711 has thermal shutdown set at 150 Above this value , the switching. The part resumes normal operations when temperature drops below 130 The over-current protection provides cycle-by-cycle current limit ...

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 Range Typical application circuit with external components is shown on page 1. ...

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 time between command pulses or two command sets ...

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 node voltage Ch 3 (red) – Inductor current (blue © 2010 IXYS Corp. Characteristics subject to change without notice = 1 μ ...

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 3(red) – LED Current. Ch4 (blue OUT Waveforms at PWM LED Current Regulation Ch 1 (yellow) – PWM signal at 30 kHz 25% duty cycle C2 (green) – ...

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 LED string anode 5 V OUT terminal to this pin. High Voltage Bypass; Connect a 0.01 µF capacitor ...

Page 7

... IXYS Corp. Characteristics subject to change without notice Figure 3. LDS8711 Functional Block Diagram The LDS8711 has soft start function that prevent high input current spike at device’ wake-up. The EN/PWM pin should be held low for more than completely turn device in low current SETUP1, shutdown mode ...

Page 8

... Figure 2). If LDS8711 is not able recognize command due some error in programming or transmit, it will go in shutdown mode after 10 ms timeout Once in PWM mode, LDS8711 is not able recognize Smart OneWire™ Interface commands and requires restart to reprogram LED current. Protection Mode The output voltage V ...

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 capacitors and inductor. The input and output ceramic capacitors (X5R or X7R type) should located as close to the device’ ...

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 0.500 Bsc L 0.350 0.400 Note: 1. All dimensions are in millimeters 2. Complies with JEDEC Standard MO-220 © ...

Page 11

... All packages are RoHS-compliant (Lead-free, Halogen-free). 2) The standard lead finish is Matte-Tin. 3) The device used in the above example is a LDS8711 XXX–T2-300 (2x3 TDFN, Tape & Reel LED Current). 4) For additional package and current options, please contact your nearest IXYS Corp. Sales office. © 2010 IXYS Corp. ...

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 THE RIGHTS OF THIRD PARTIES WITH RESPECT TO ANY PARTICULAR USE OR APPLICATION AND SPECIFICALLY DISCLAIMS ANY AND ALL LIABILITY ARISING OUT OF ANY SUCH USE OR APPLICATION, INCLUDING BUT NOT LIMITED TO, CONSEQUENTIAL OR INCIDENTAL DAMAGES ...

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