BD6067GU_11 ROHM [Rohm], BD6067GU_11 Datasheet - Page 6

• Manufacturer Part Number: BD6067GU_11
• Description: White Backlight LED Drivers for Small to Medium LCD Panels (Switching Regulator Type)
• Manufacturer: ROHM [Rohm]

© 2011 ROHM Co., Ltd. All rights reserved.
BD6067GU, BD6069GUT, BD6071HFN, BD6072HFN
►BD6067GU
●Over voltage Protection
www.rohm.com
BD6067GU has an over voltage protection feature. When a fault occurs, for example, IC is disconnected from LED, an
excessive voltage rise may cause the SW pin and VOUT pin to exceed the absolute maximum ratings respectively, resulting
in IC damage. For this reason, when VOUT is 30V or more, over voltage protection is activated to turn Q1 off so that the SW
pin and VOUT pin don’t exceed the absolute maximum ratings.
At this time, the IC state changes from active to inactive and the output voltage drops slowly. Then, when the output voltage
falls below the over voltage protection hysteresis level, the output voltage continues to rise up to 30V again.
This protection circuit is shown in Fig.16.
▪ Control by DC Voltage
Vin
BD067GU has a built-in function for LED current control by DC voltage and can control the current by VDAC pin control
voltage.
Fig.14 Brightness Control by BD6067GU DAC
Vin
GNDA
Fig.16 Block Diagram for Short-circuit Protection and over voltage Protection
22μH
L1
SW
BD6067GU
GND
EN
VDAC
Q1
VFB
Vout
SW
DAC
D1
V
1μF
fb
Driver
D1
10Ω
R1
Vout
6/29
OVER VOLTAGE REF
I
LED
Cout
OVER Detector
Fig.15 DAC Constant Current Characteristics by
25
20
15
10
5
0
Control
0
0.5
DAC [V] (Vfb=200mV)
DAC Control
1
1.5
2011.01 - Rev.C
Technical Note
2
2.5