BD6581GU-E2 Rohm Semiconductor, BD6581GU-E2 Datasheet - Page 13

• Manufacturer Part Number: BD6581GU-E2
• Description: IC LED DVR WHT BCKLGHT VCSP85H2
• Manufacturer: Rohm Semiconductor
• Series: -r

Specifications of BD6581GU-E2

• Constant Current: -
• Constant Voltage: -
• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 6
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: 800kHz ~ 1.2MHz
• Voltage - Supply: 2.7 V ~ 22 V
• Voltage - Output: 44.7 V
• Mounting Type: *
• Package / Case: *
• Operating Temperature: -30°C ~ 85°C
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

●Start to Use PWMDRV Terminal for the PWM Control, PWM Operating
BD6581GU
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After RSTB and PWMPOW is changing L → H, input PWM to PWMDRV terminal.
There is no constraint in turn of RSTB and PWMPOW.
After RSTB and PWMPOW is changing L → H as follows Fig.37, when it is not input PWM to PWMDRV pin but input L,
boost of DC/DC is unstable state because current driver doesn’t pass current.
The starting current is pulled from each LED terminal and pressure up operating is stabilized to escape from this state.
Also, the starting current can be set up by the resistance value connected to the ISETL terminal.
After starting, as the starting current in PWM brightness control become useless, the starting current is set up 0mA at the
second rise time of PWMDRV automatically as follows Fig.37.
In case of lighting → light off → lighting, when it turns off the lights with PWM=L and It starts without soft start because of
soft start period was end when it sets PWM modulated light again.
But the peak current of the coil changes owing to discharge of output capacitor, It may flow to the over current limit value, as
follows Fig.38. Because soft start can be used when it turns off the lights with RSTB=L, The peak current of the coil can be
suppressed, as follows Fig.39 and this process of light off is recommended.
Current driver of
Output voltage
starting current
PWMPOW
PWMDRV
LED pin
RSTB
Fig.39 Light off control of PWMDRV pin at PWM control on RSTB=L
Fig.38 Light off control of PWMDRV pin at PWM control on PWM=L
Output Voltage
Output Voltage
Current coil
Current coil
PWMPOW
PWMPOW
PWMDRV
PWMDRV
Fig. 37 Off timing of starting current at PWMDRV=L
RSTB
RSTB
L
ON
OFF
H
13/26
ON
L
OFF
H
L
H
2010.03 - Rev.A
Technical Note
L