BCR420UFD / BCR421UFD

Document number: DS38588 Rev. 3 - 2

11 of 13

www.diodes.com

January 2018

© Diodes Incorporated

BCR420UFD / BCR421UFD

To remove the potential of incorrect connection of the power supply

damaging the lamp

’s LEDs, many systems use some form of

reverse polarity protection.

One solution for reverse input polarity protection is to simply use a

less power. A circuit example is presented in Figure 5 which

protects the light engine although it will not function until the problem

is diagnosed and corrected. An SDM10U45LP (0.1A/45V) is shown,

Other

reverse

voltage

ratings

are

available

from

Diodes

Incorporated

’s website such as the SBR02U100LP (0.2A/100V) or

SBR0220LP (0.2A/20V).

(Optional)

Figure 5 Application Circuit for LED Driver

with Reverse Polarity Protection

While automotive applications commonly use this method for

reverse battery protection, an alternative approach shown in Figure

6, provides reverse polarity protection and corrects the reversed

polarity, allowing the light engine to function.

single package, reducing the power dissipated and maximizes the

voltage across the LED stack.

BCR421U. In such higher current configurations adequate enable

current is provided by increasing the enable voltage.

(Optional)

2.1

Figure 6 Application Circuit for LED Driver with

Assured Operation Regardless Of Polarity

Figure 7 Example for 350mA Operation using BCR421U