LDS8711008-T2-300 IXYS [IXYS Corporation], LDS8711008-T2-300 Datasheet - Page 7

• Manufacturer Part Number: LDS8711008-T2-300
• Description: High Efficiency 10 LED Driver with No External Schottky
• Manufacturer: IXYS [IXYS Corporation]

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 will operate. If first pulse is equal t
LED current sets to factory programmed value and
every next incoming pulse will be rec ognized as
PWM signal. If first pulse is equal t
enters Smart OneWire™ interface mode and wait for
command. Every next of 16 incoming pulses will be
recognized as command. After LDS8711 accepts
command, the current sets in respect to programmed
value, and device changes mode to PWM. If device is
not able to recognize command due some error, it
enters shutdown mode after 10 ms.
currents, the device remains in operating mode. The
low dropout Current regulator performs well at V
voltage up to 250 mV above summary LED forward
voltage significantly increasing driver’s efficiency.
If the input voltage is insufficient or falls to a level
where the regulated currents cannot be maintained,
the Under-Voltage protection turns device off setting
it in shutdown mode.
© 2010 IXYS Corp.
Characteristics subject to change without notice
If the input voltage is sufficient to regulate all LED
Figure 3. LDS8711 Functional Block Diagram
SETUP2,
device
SETUP1,
OUT
7
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
10 ms to completely turn device in low current
shutdown mode.
LED Current Setting
The maximum current value in the LED string may be
factory preset in the range from 10 to 30 mA in 0.125
mA steps, or set by Smart OneWire™ interface in the
range from 0.125 to 32 mA. The average LED string
current that determines LED brightness may be
controlled applying PWM signal to the EN/PWM pin.
The maximum PWM frequency is 30 kHz, while
frequiencies below 100 Hz are not recommended to
avoid visible LED flikering. Duty cycle that determines
average LED string current may vary in the range
from 5% to 100% at 1 k Hz or from 20% to 100% at
30 kHz with high linearity current regulation.
It gives possibility regulate brightness either in DC
mode with changing color temperature, or in PWM
mode with stable color temperature.
To start LDS8711 in PWM Mode, the first positive
pulse applied to EN/PWM pin after power-up should
be equal t
SETUP1
and followed by EN/PWM pin LOW
Doc. No. 8711DS, Rev. N1.0