BD8381EFV-M Ver la hoja de datos (PDF) - ROHM Semiconductor

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BD8381EFV-M

LED Drivers for Automotive Light

ROHM Semiconductor 

BD8381EFV-M

Technical Note

・LED Short Detection

When the voltage between LEDR-pin and LEDC-pin  0.2 (TYP), the internal counter starts operating, and approximately

after 100ms (when FOSC = 300kHz) the operation latches off. With the PWM brightness control, the detecting operation

is processed only when PWMOUT-pin = High. If the condition of the detection operation is released before 100ms (when

FOSC = 300kHz), then the internal counter resets.

There is a possibility that the LED short detection malfunctions when the difference of Vf is large. Therefore, please

adjust external resistance for connected Vf. It is recommended 2V-3V to the input range of LEDR and LEDC.

※The counter frequency is the DCDC switching frequency determined by the RT. The latch proceeds at the count of 32770.

○High luminance LED (multichip) with built-in LED of X piece in 1chip when using Y piece

VOUT(DC/DC output）

Y piece

X piece

PWMOUT

FB

R3

LEDR

R4

R1

LEDC

R2

Setting method

R1：R2 = X：1

R3：R4 = ( X + 1 ) Y – 1：1

Fig. 15

○When using the single chip

VOUT(DC/DC output）

Y piece

PWMOUT

R3

LEDR

R4

R1

LEDC

R2

FB

Fig. 16

Setting method

R1：R2 = 1：1

R3：R4 = 2Y – 1：1

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2011.04 - Rev.A

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