Datasheet

Datasheet
Datasheet
23/34
BD9271KUT
TSZ02201-0F1F0C100260-1-2
© 2013 ROHM Co., Ltd. All rights reserved.
27.Feb.2015 Rev.004
www.rohm.com
TSZ22111・15・001
◆Normal operating mode, start sequence
When you light the LED by general SPI control, please follow the sequence below.
① Input the power supply of VCC.
(If the voltage of VCC pin becomes higher than 7.0V, the analog block starts operating.)
② Input the power supply of DVDD.
(If the voltage of DVDD pin becomes higher than 2.8V, reset of the logic block is released.)
③ Launch the STB from L to H.
(The voltage of VREF5V pin charged by STB=H. If the voltage of VREF5V pin becomes higher than 4.5V,
the LED driver starts operating.)
④ Write the data to the register by SPI control, then set the LED driver.
(Set of the LED driver operation.)
⑤ Input the VSYNC, HSYNC signal which is for PWM dimming.
(Set of the PWM dimming operation.)
start sequence characteristics:
timing Symbol
Need time
unit
min
① - ② t1 5.0 us
② - ③ t2 1.0 us
③ - ④ t3 85.0 us
④ - ⑤
t4
tHSYNCCYC
(HSYNC 1cycle)
-
◆PWM dimming mode, Boot sequence
In BD9271KUT, as process mode, there is a test mode for running the LED driver, even there is no
environment for SPI control. After inputting the power supply of VCC and DVDD, by setting the STB to H, it
can be changed to PWM dimming operation mode achieved by duty control immediately. And the operating
conditions are as below
Power supply：VCC and DVDD are in normal operating range.
・VCC=9.0V～35V, DVDD=3.0V～3.6V
Settings of LED driver（Default settings of register）
・Set all CHs to ON state （LED １CH～16CH）
・Setting voltage for LED current（Voltage of S1～S16 pin）：0.30V
・Reference voltage of error amplifier：0.60V
・Soft start setting：16 count of VSYNC
※C_vref5v = 1uF
t1
t2
t3
t4
By inputting the SPI control signal
before the PWM signal of VSYNC
and HSYNC, LED can be controlled
with register settings.
Figure 20. Starting Sequence for normal operation