Description

he BCR420U/BCR421U monolithically integrates a transistor, diodes and resistors to function as a Constant Current Regulator (CCR) for linear LED driving. The device regulates with a preset 10mA nominal that can be adjusted with external resistor up to 350mA. It is designed for driving LEDs in strings and will reduce current at increasing temperatures to self-protect. Operating as a series linear CCR for LED string current control, it can be used in multiple applications, as long as the maximum supply voltage to the device < 40V.

With the low-side control, the BCR421U has an Enable (EN) pin which can be pulse-width modulated (PWM) up to 10 kHz by a micro controller for LED dimming.

With no need for additional external components, this CCR is fully integrated into a SOT26 minimizing PCB area and component count.

Feature(s)

LED Constant Current Regulator using NPN Emitter-Follower with Emitter Resistor to Current Limit
I_out = 10mA ± 10% Constant Current (Preset)
I_out up to 350mA adjustable with an External Resistor
V_out = 40V Supply Voltage
P_d up to 1W in SOT26 (SC-74)
Negative temperature coefficient (NTC) reduces IOUT with increasing temperature
Parallel Devices to Increase Regulated Current
Totally Lead-Free & Fully RoHS Compliant
Halogen and Antimony Free. “Green” Device
Qualified to AEC-Q101 Standards for High Reliability

Application(s)

Constant Current Regulation (CCR) in:

Automotive Interior Lighting
Emergency Lighting
Signage, Advertising, Decorative and Architectural Lighting
Retail Lighting in Fridges, Freezer Cases and Vending Machines

Specifications & Technical Documents

Product Parameters

AEC Qualified	No
Compliance (Only Automotive Supports PPAP)	Standard
Topology	Linear LED Driver
Minimum Supply Voltage (V)	1.4 V
Maximum Supply Voltage (V)	40 V
Maximum V_{OUT (V)}	40 V
Number of Channels	1
LED Current Sense Voltage (mV)	700 mV
Low Dropout VSAT (mV)	950@10mA (Typ) mV
Output Current (mA)	350 mA
Channel Max. Output Current (mA)	10 Preset mA
Accuracy (%)	10 %
Control Interface/Protocols	PWM
Dimming (PWM)	Micro PWM Controlled
Temperature Range (°C)	-55 to 150 °C
Moisture Sensitivity Level (MSL)	1

Technical Documents

SPICE Model

BCR421UW6.spice.txt

Calculators

BCR4XX-calculator-V2.xls (149 KB)

Recommended Soldering Techniques

TN1.pdf

RoHS CofC

RoHSFile

Purchase & Availability

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Product Change Notices (PCNs)

A PCN may only apply to specific orderable part numbers in this datasheet. Please refer to the corresponding PCN to see the exact orderable part number(s) affected.

PCN #	Issue Date	Implementation Date	Subject
PCN-2770	2025-10-30	2025-10-30	Add Fab Site Code, Country of Diffusion (COD) and Assembly Site Origin (ASO) on Product and Shipping Labels for all Diodes Products
PCN-2495	2021-03-31	2021-07-01	Qualification of Additional Assembly & Test Sites and Additional Wafer Back Grinding and Back Metal Process Source for Select Discrete Products

BCR421UW6