BCR421U

• Input voltage up to 5V (Above 5V possible up to 18V but with 0.1W power dissipation!)
• Maximum power dissipation 0.2W (25°C, up to 5V) (established safe value) (Due to the small size of the PCB)
• Maximum power dissipation 0.1W (25°C, from 5V up to 18V - because it has its own power consumption of 10mA above 5V) (established safe value) (Due to the small size of the PCB)
• Supports dimming through PWM up to 25kHz
• Reverse polarity protection is not officially supported, but it works

BCR420U

• Input voltage up to 40V
• Maximum power dissipation 0.2W (25°C) (established safe value) (Due to the small size of the PCB)
• Dimming is not officially supported but works up to a 29V voltage drop on LED driver
• Reverse polarity protection is not officially supported, but it works

Maximum power dissipation (Pd) 0.2W (25°C)! It has no officially polarity reversal protection

Example of calculation BCR421U:

• Input voltage (VCC): 5V
• LED forward voltage (Lfv): 3V
• LED current (Lc): 0.01A/0.02A (10mA/20mA)

• (VCC - Lfv) * Lc = Pd
• (5 - 3) * 0.01 = 0.02W (0.02 <= 0.2 (OK))
• (5 - 3) * 0.02 = 0.04W (0.04 <= 0.2 (OK))

• Input voltage (VCC): 12V/18V
• LED forward voltage (Lfv): 3V
• LED current (Lc): 0.01A/0.02A (10mA/20mA)

• (VCC - Lfv) * Lc = Pd
• (12 - 3) * 0.01 = 0.09W (0.09 <= 0.1 (OK))
• (12 - 3) * 0.02 = 0.18W (0.18 <= 0.1 (BAD))
• (18 - 3) * 0.01 = 0.15W (0.15 <= 0.1 (BAD))
• (18 - 3) * 0.02 = 0.3W (0.3 >= 0.1 (BAD))

Example of calculation BCR420U:

• Input voltage (VCC): 24V/40V
• LED forward voltage (Lfv): 3 x 3V (9V)/10 x 3V (30V)
• LED current (Lc): 0.01A/0.02A (10mA/20mA)

• (VCC - Lfv) * Lc = Pd
• (24 - 9) * 0.01 = 0.15W (0.15 <= 0.2 (OK))
• (24 - 9) * 0.02 = 0.3W (0.3 >= 0.2 (BAD))
• (40 - 30) * 0.01 = 0.1W (0.1 <= 0.2 (OK))
• (40 - 30) * 0.02 = 0.2W (0.2 <= 0.2 (OK))