BD8119FM-M_11 Datasheet, PDF (9/21 Pages) Rohm – White Backlight LED Driver for Medium to Large LCD Panels (Switching Regulator Type)

BD8119FM-M
Technical Note
・LED Short Detection
When the LED-pin voltage  4.7V (TYP) as well as OVP-pin voltage  1.6V (TYP) simultaneously the internal counter
starts operating, and approximately after 100ms (when FOSC = 300kHz) the only detected channel (as LED short)
latches off. With the PWM brightness control, the detecting operation is processed only when PWM-pin = High. If the
condition of the detection operation is released before 100ms (when FOSC = 300kHz), then the internal counter resets.
※ The counter frequency is the DCDC switching frequency determined by the RT. The latch proceeds at the count of 32770.
Protection
UVLO
TSD
OVP
Detecting Condition
[Detect]
[Release]
VREG<4.3V
VREG>4.5V
Tj>175℃
Tj<150℃
VOVP>2.0V
VOVP<1.45V
Operation after detect
All blocks shut down
All blocks (but except REG)
shut down
SS discharged
OCP
VCS≦VCC-0.6V
SCP
VLED<0.3V
(100ms delay when
FOSC=300kHz)
LED open VLED<0.3V & VOVP>1.7V
LED short
VLED>4.7V & VOVP<1.6V
(100ms delay when
FOSC=300kHz)
VCS>VCC-0.6V
EN or UVLO
EN or UVLO
EN or UVLO
SS discharged
Counter starts and then latches off
all blocks (but except REG)
The only detected channel latches off
The only detected channel latches off
(after the counter sets)
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2011.08 - Rev.B