BD60A00NUX ROHM [Rohm], BD60A00NUX Datasheet - Page 11

• Manufacturer Part Number: BD60A00NUX
• Description: White Backlight LED Drivers for Small to Medium LCD Panels (Switching Regulator Type)
• Manufacturer: ROHM [Rohm]

●Operating of the application deficiency
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© 2011 ROHM Co., Ltd. All rights reserved.
BD60A00NUX, BD60A60NUX
1)
2)
When 1 LED or 1string OPEN during the operating
Since FB terminal is set to 0V when set to OPEN, Output boosts up to the over voltage protection voltage. When over
voltage is detected, the boosting operation stops and then output voltage goes down slowly. Later, if output voltage
becomes less than hysteresis of over current protection, output voltage keeps boosting up to over voltage protection
voltage again.
When LED short-circuited in the plural
Even if one LED short-circuits during boost operation, it usually passes along LED and it is turned on. By making LED
shorted, FB terminal voltage increases by LED VF. Therefore output voltage becomes lower by LED VF, and the
condition turns to be normal.
output
FB
VOUT
FB
FB
Fig.10 FB terminal – VOUT terminal shorted
LED current
Fig. 9 One LED shorted
Fig. 8 LED open detect
LED current
connection
FB voltage
VOUT
LED
Vout
FB
11/22
LED current 20mA
0.7V
VOUT
20mA
FB
normal
20mA
LED short
LED short
0.7V
100uS
0.7V+VF of LED
5.9V
0.1mA
VF of LED
VF of LED
Hysteresis voltage
Open
0mA
VIN
Technical Note
2011.12 - Rev.A