Cantor Colburn LLP
Light emitting apparatus
A current driving circuit is connected to an LED terminal LEDi, and generates an intermittent driving current ILEDi that corresponds to a dimming pulse signal PWMi. An error amplifier generates a feedback voltage VFB that corresponds to the difference between a detection voltage VLEDi and a predetermined reference voltage VREF. A pulse modulator generates a pulse signal having a duty ratio that corresponds to the feedback voltage VFB. A fault detection comparator COMP_OPENi generates a fault detection signal OPEN_DET which is asserted when the detection voltage VLEDi is lower than a predetermined threshold voltage VOPENDET. A forced turn-off circuit instructs the current driving circuit to suspend the generation of the driving current ILEDi during a predetermined period after a switching power supply starts to operate. The fault detection circuit detects whether or not the fault detection signal OPEN_DETi has been asserted in a predetermined period.
ROHM CO., LTD.
H H H H G H H
H05B H05B H02M H05B G09G H05B H05B
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Masao Hiroki
Yonemaru Kikuchi