BD6590MUV_11 Datasheet, PDF (11/27 Pages) Rohm – White Backlight LED Driver for Medium to Large LCD Panels (Switching Regulator Type)

BD6590MUV
●Control signal input timing
VBAT
4.1V
1
2
Min. 100µs
PWMPOW
PWMDRV
VREG
DC/DC VOUT
Fig.12 Control signal timing
Technical Note
0V
VBAT
10kΩ
5V
P IN
Rin
GND
Fig.13 Voltage with a control sign higher than VBAT
Example corresponding to application of conditions
In case you input control signs, such as PWMPOW, and PWMDRV, in the condition that the standup of supply voltage
(VBAT) is not completed, be careful of the following point.
①Input each control signal after VBAT exceeds 4.1V.
②When you input PWMPOW during the standup of VBAT, please give the standup time as Min.100µs
from 4.1V to stable voltage for VBAT.
There is no timing limitation at each input signal of PWMPOW and PWMDRV.
If each control sign changes into a condition higher than VBAT in (1) and (2), it goes via the ESD custody diode by the side of
VBAT of each terminal. A power supply is supplied to VBAT and there is a possibility of malfunctioning. In order to avoid this
condition, as shown in the above figure, please insert about 10kΩ in a signal line, and apply current qualification. Please
confirm an internal pull down resistor in the block diagram and electrical property.
●Start control (PWMPOW) and select LED current driver (PWMDRV)
BD6590MUV can control the IC system by PWMPOW, and IC can power off compulsory by setting 0.9V or below. Also,
It powers on PWMPOW is at more than 2.1V.
After it’s selected to PWMPOW=H, When it is selected at PWMDRV=H, LED current decided with ISET resistance flow.
Next, When it is selected at PWMDRV=L, LED current stop to flow.
RSTB
L
H
H
H
H
PWMPOW
H, L
L
H
L
H
PWMDRV
H, L
L
L
H
H
IC
LED current
Off
OFF
Off
OFF
On
OFF
Off
OFF
On
Current decided with ISET
●How to select the number of LED lines of the current driver
When the number of LED lines of the current driver is reduced, the un-select can be available by setting the unnecessary
LED1~6 terminals OPEN. In the case of using 4 lines and so on, please connect the unnecessary 2 lines OPEN.
Then please set RSTB,PWMPOW and PWMDRV “H” and finish selecting the lines within the process of softstart. If the level
of over voltage limit is set too high, the connected LED lines exceed LED terminal over voltage protect and are judged as
unnecessary lines.
Please make it sure referring “How to set over voltage limit (p.7)”.
Additionally, once the terminals are judged as unnecessary, this information never can be reset without setting RSTB,
PWMPOW and PWMDRV “L”.
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11/26
2011.07 - Rev.B