BCR420UW6 / BCR421UW6
LINEAR LED CONSTANT CURRENT REGULATOR IN SOT26
Description
The BCR420U and BCR421U monolithically integrate transistors,
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 an 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 is < 40V.
With the low-side control, the BCR421U has an Enable (EN) pin
which can be pulse-width modulated (PWM) up to 25kHz by a micro-
controller for LED dimming.
With no need for additional external components, this CCR is fully
integrated into an SOT26 / SC74R minimizing PCB area and
component count.
Features
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 / SC74R
Low-Side Control Enabling PWM Input < 25kHz (BCR421U)
Negative Temperature Coefficient (NTC) Reduces I
OUT
with
Increasing Temperature
Parallel Devices to Increase Regulated Current
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Qualified to AEC-Q101 Standards for High Reliability
Automotive-Compliant Parts are Available Under Separate
Datasheet (BCR420UW6Q/BCR421UW6Q)
Mechanical Data
Case: SOT26 / SC74R
Case Material: Molded Plastic. ―Green‖ Molding Compound.
UL Flammability Rating 94V-0
Moisture Sensitivity: Level 1 per J-STD-020
Terminals: Finish - Matte Tin Plated Leads. Solderable per MIL-
STD-202, Method 208
Weight: 0.018 grams (Approximate)
Applications
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
SOT26 / SC74R
EN
OUT
BCR420U
BCR421U
Rext
R
EXT
(Optional)
(Optional)
GND
EN
OUT
OUT
R
EXT
OUT
GND
Pin Name
OUT
EN
R
EXT
GND
Pin Function
Regulated Output Current
Enable for Biasing
Transistor
External Resistor for
Adjusting Output Current
Power Ground
Top View
Internal Device
Schematic
Top View
Pin-Out
Ordering Information
(Note 4)
Product
BCR420UW6-7
BCR421UW6-7
Notes:
Compliance
AEC-Q101
AEC-Q101
Marking
420
421
Reel Size (inches)
7
7
Tape Width (mm)
8
8
Quantity per Reel
3,000
3,000
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-free "Green‖ products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
4. For packaging details, go to our website at http://www.diodes.com/products/packages.html.
BCR420UW6 / BCR421UW6
Document number: DS37667 Rev. 4 - 2
1 of 13
www.diodes.com
June 2016
© Diodes Incorporated
BCR420UW6 / BCR421UW6
Marking Information
SOT26 / SC74R
xxx = Part Marking (See Ordering Information)
YM = Date Code Marking
Y = Year (ex: D = 2016)
M = Month (ex: 9 = September)
xxx
Date Code Key
Year
Code
Month
Code
2016
D
Jan
1
Feb
2
2017
E
Mar
3
Apr
4
2018
F
May
5
2019
G
Jun
6
Jul
7
2020
H
Aug
8
Sep
9
2021
I
Oct
O
Nov
N
2022
J
Dec
D
Absolute Maximum Ratings
(Voltage relative to GND, @T
A
= +25° unless otherwise specified.)
C,
Characteristic
Enable Voltage
Output Current
Output Voltage
Reverse Voltage Between all Terminals
BCR420U
BCR421U
Symbol
V
EN
I
OUT
V
OUT
V
R
Value
40
18
500
40
0.5
Unit
V
mA
V
V
Thermal Characteristics
(@T
A
= +25° unless otherwise specified.)
C,
Characteristic
Power Dissipation
Thermal Resistance, Junction to Ambient
Thermal Resistance, Junction to Lead
Recommended Operating Junction Temperature Range
Maximum Operating Junction and Storage Temperature Range
(Note 5)
(Note 6)
(Note 5)
(Note 6)
(Note 7)
Symbol
P
D
R
θJA
R
θJL
T
J
T
J
, T
STG
Value
1,190
912
105
137
50
-55 to +150
-65 to +150
°
C
Unit
mW
°
C/W
ESD Ratings
(Note 8)
Characteristics
Electrostatic Discharge – Human Body
Model
Electrostatic Discharge – Machine Model
Notes:
Symbols
BCR420U
BCR421U
BCR420U
BCR421U
HBM
MM
Value
500
1,000
300
400
Unit
V
V
V
V
JEDEC Class
1B
1C
B
C
5. For a device mounted with the OUT leads on 50mm x 50mm 1oz copper that is on a single-sided 1.6mm FR4 PCB; device is measured under still
air conditions while operating in steady-state.
6. Same as Note 5, except mounted on 25mm x 25mm 1oz copper.
7. R
θJL
= Thermal resistance from junction to solder-point (at the end of the OUT leads).
8. Refer to JEDEC specification JESD22-A114 and JESD22-A115
.
BCR420UW6 / BCR421UW6
Document number: DS37667 Rev. 4 - 2
2 of 13
www.diodes.com
June 2016
© Diodes Incorporated
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