BD6079GWL Datasheet, PDF (10/41 Pages) Rohm – White LEDs Driver

BD6079GWL
Datasheet
˔Modes of operation
BD6079GWL is turned on DC/DC by EN signal. After DC/DC turned on, BD6079GWL’s current driver has 2 operation
sequences that change to next EN rising edge timing.
<Case1: Startup at PWM duty 100% >
BD6079GWL’s DC/DC starts up and boosts up 7.5V within 1.2ms(Typ.) at first EN signal coming.
After 11ms (Typ.), go to normal boost mode and LEDs turn on. At the first driver start-up, BD6079GWL checks LED’s setting
(open or short). If LED is detected to be open or short, driver will cut off current until shutdown mode. If EN signal is not
asserted again and 33ms (Typ.) have elapsed after final falling edge, BD6079GWL driver goes to shutdown mode
(Figure 21).
Turn on(NB=L, PWM duty = 100%)
11ms(Typ.)
33ms(Typ.)
EN terminal
H
NB terminal
L
REFEN
(Internal enable signal)
Initial boost
Soft start(1.2ms(Typ.))
7.5V(Typ.)
H
Shutdown
VOUT terminal
LED current
Figure 21. Turn ON (NB=L, PWM duty=100%)
<Case2: Startup with PWM dimming at PWM frequency=200Hz>
BD6079GWL’s DC/DC starts up and boosts up 7.5V within 1.2ms (Typ.) at first EN signal coming.
DC/DC will be turned on regardless of H time of EN (Figure22).
If the next EN rising edge is coming within 11ms (Typ.), BD6079GWL will go to the normal boost mode and LEDs will turn
on. At the first driver start-up, LED driver checks LED’s setting (open or short). If LED is detected to be open or short, driver
will cut off current until shutdown mode. If EN signal is not asserted again and 33ms (Typ.) have elapsed after final falling
edge, LED driver goes to shutdown mode. (Figure 22, Figure 23)
Turn on(NB=L, PWM=200Hz, duty=75%)
200Hz(5ms)
Duty=75%
EN terminal
H
L
NB terminal
L
REFEN
(Internal enable signal)
Initial boost
Soft start(1.2ms(Typ.))
7.5V(Typ.)
(5ms)
33ms(Typ.)
H
L
Shutdown
VOUT terminal
LED current
Figure 22. Turn ON (NB=L, PWM Frequency=200Hz, duty=75%)
Turn on(NB=L, PWM=200Hz, duty=0.1%(H=5μs))
200Hz(5ms)
EN terminal
Duty=0.1%(H=5μs)
L
NB terminal
L
REFEN
(Internal enable signal)
Initial boost
Soft start(1.2ms(Typ.))
7.5V(Typ.)
(5ms)
33ms(Typ.)
L
Shutdown
VOUT terminal
LED current
Figure 23. Turn ON (NB=L, PWM Frequency=200Hz, duty=0.1%(H=5μs))
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TSZ02201-0G3G0C200340-1-2
14.Mar.2013 Rev.001