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BCR421UW6Q Datasheet

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Datasheet

BCR421UW6Q
Document number: DS38302 Rev. 1 - 2
1 of 11
www.diodes.com
October 2015
© Diodes Incorporated
BCR421UW6Q
Linear LED Constant Current Regulator in SOT26
Description
This Linear LED driver is designed to meet the stringent requirements
of automotive applications.
The BCR421U monolithically integrates transistors, diodes and
resistors to function as a Constant Current Regulators (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 10 kHz by a micro-
controller for LED dimming.
With no need for additional external components, this CCR is fully
integrated into an SOT26 minimizing PCB area and component count.
Applications
Constant Current Regulation (CCR) in:
Automotive Interior Lighting
Mood and Decorative Lighting
Features
LED Constant Current Regulator using NPN Emitter-Follower with
Emitter Resistor to Current Limit
IOUT 10mA ± 10% Constant Current (Preset)
IOUT up to 350mA Adjustable with an External Resistor
VOUT 40V Supply Voltage
PD up to 1W in SOT26 (SC-74)
Low-Side Control Enabling PWM Input < 10kHz
Negative Temperature Coefficient (NTC) Reduces IOUT 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
PPAP Capable (Note 4)
Mechanical Data
Case: SOT26 (SC-74)
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)
Rext
(Optional)
GND
BCR421U
EN OUT
Ordering Information (Note 5)
Product
Marking
Reel Size (inches)
Tape Width (mm)
Quantity per Reel
BCR421UW6Q-7
421
7
8
3,000
Notes: 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. Automotive products are AEC-Q101 qualified and are PPAP capable. Refer to http://www.diodes.com/quality/product_compliance_definitions/.
5. For packaging details, go to our website at http://www.diodes.com/products/packages.html.
Pin Name
Pin Function
OUT
Regulated Output Current
EN
Enable for Biasing
Transistor
REXT
External Resistor for
Adjusting Output Current
GND
Power Ground
Top View
Pin-Out
SOT26 (SC-74)
Top View
EN
OUT
OUT
Rext
GND
OUT
Internal Device
Schematic
BCR421UW6Q
Document number: DS38302 Rev. 1 - 2
2 of 11
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October 2015
© Diodes Incorporated
BCR421UW6Q
Marking Information
Date Code Key
Year
2015
2016
2017
2018
2019
2020
2021
Code
C
D
E
F
G
H
I
Month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Code
1
2
3
4
5
6
7
8
9
O
N
D
Absolute Maximum Ratings (Voltage relative to GND, @TA = +25°C, unless otherwise specified.)
Characteristic
Symbol
Value
Unit
Enable Voltage
VEN
18
V
Output Current
IOUT
500
mA
Output Voltage
VOUT
40
V
Reverse Voltage Between All Terminals
VR
0.5
V
Thermal Characteristics (@TA = +25°C, unless otherwise specified.)
Characteristic
Symbol
Value
Unit
Power Dissipation
(Note 6)
PD
1,190
mW
(Note 7)
912
Thermal Resistance, Junction to Ambient
(Note 6)
RθJA
105
°C/W
(Note 7)
137
Thermal Resistance, Junction to Lead
(Note 8)
RθJL
50
Recommended Operating Junction Temperature Range
TJ
-55 to +150
°C
Maximum Operating Junction and Storage Temperature Range
TJ , TSTG
-65 to +150
ESD Ratings (Note 9)
Characteristics
Symbols
Value
JEDEC Class
Electrostatic Discharge Human Body Model
HBM
1,000
1C
Electrostatic Discharge Machine Model
MM
400
C
Notes: 6. 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.
7. Same as Note 5, except mounted on 25mm x 25mm 1oz copper.
8. RθJL = Thermal resistance from junction to solder-point (at the end of the OUT leads).
9. Refer to JEDEC specification JESD22-A114 and JESD22-A115.
xxx = Part Marking (See Ordering Information)
YM = Date Code Marking
Y = Year (ex: C = 2015)
M = Month (ex: 9 = September)
xxx
SOT26 (SC-74)
BCR421UW6Q
Document number: DS38302 Rev. 1 - 2
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BCR421UW6Q
Electrical Characteristics (@TA = +25°C, unless otherwise specified.)
Characteristic
Symbol
Min
Typ
Max
Unit
Test Condition
Collector-Emitter Breakdown Voltage
BVCEO
40
V
IC = 1mA
Enable Current
IEN
1.2
mA
VEN = 3.3V
DC Current Gain
hFE
200
350
500
IC = 50mA; VCE = 1V
Internal Resistor
RINT
85
95
105
IRINT = 10mA
Bias Resistor
RB
1.5
kΩ
Output Current
IOUT
9
10
11
mA
VOUT = 1.4V; VEN = 3.3V
Output Current at REXT = 5.1Ω
IOUT
150
mA
VOUT > 2.0V; VEN = 3.3V
Voltage Drop (VREXT)
VDROP
0.85
0.95
1.05
V
IOUT = 10mA
Minimum Output Voltage
VOUT(MIN)
1.4
V
IOUT > 18mA
Output Current Change vs. Temperature
ΔIOUT/IOUT
-0.2
%/°C
VOUT > 2.0V; VEN = 3.3V
Output Current Change vs.
Supply Voltage
ΔIOUT/IOUT
1
%/V
VOUT > 2.0V; VEN = 3.3V
BCR421UW6Q
Document number: DS38302 Rev. 1 - 2
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BCR421UW6Q
Typical Thermal Characteristics (@TA = +25°C, unless otherwise specified.)
100 1000
0
100
200
300
400
500
600
700
800
Rth(JA) VS Cu Area
Copper Area (mm2)
100µ 1m 10m 100m 110 100 1k
0
25
50
75
100
125
Tamb=25°C
50mm * 50mm
1oz Cu
Transient Thermal Impedance
D=0.5
D=0.2
D=0.1
Single Pulse
D=0.05
Thermal Resistance (°C/W)
Pulse Width (s) 100µ 1m 10m 100m 110 100 1k
1
10 Tamb=25°C
50mm * 50mm
1oz Cu
Single Pulse
Pulse Power Dissipation
Pulse Width (s)
Maximum Power (W)
100µ 1m 10m 100m 110 100 1k
0
25
50
75
100
125
150
Tamb=25°C
25mm * 25mm
1oz Cu
Transient Thermal Impedance
D=0.5
D=0.2
D=0.1
Single Pulse
D=0.05
Thermal Resistance (°C/W)
Pulse Width (s) 100µ 1m 10m 100m 110 100 1k
1
10 Single Pulse
Tamb=25°C
25mm * 25mm
1oz Cu
Pulse Power Dissipation
Pulse Width (s)
Maximum Power (W)
050 100 150
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Rth(JA) (°C/W)
25mm * 25mm
1oz Cu
50mm * 50mm
1oz Cu
Derating Curve
Temperature (°C)
Max Power Dissipation (W)
BCR421UW6Q
Document number: DS38302 Rev. 1 - 2
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BCR421UW6Q
Typical Electrical Characteristics (Continued) (@TA = +25°C, unless otherwise specified.)
0246810 12
0.00
0.01
0.02
110 100
0.00
0.05
0.10
0.15
0.20
012345678910 11 12
0.00
0.04
0.08
0.12
0.16
0 2 4 6 8 10 12
0.06
0.08
0.10
0.12
0.14
0.16
0246810 12
0.02
0.03
0.04
0.05
0.06
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
0.00
0.05
0.10
0.15
Rext= open
VEN=3.3V
85°C
25°C
-40°C
VEN=3.3V
IOUT (A) IOUT (A)
IOUT (A) IOUT (A)
VOUT = 5.4V
VOUT = 1.4V
IOUT (A)
IOUT (A)
VEN vs IOUT
VOUT (V)
VOUT vs IOUT
VOUT vs IOUT
VOUT (V)
VOUT vs IOUT
VOUT (V)
Rext (Ohms)
Rext=15 Ohms
Rext= 30 Ohms
Rext= open
Rext=10 Ohms
Rext=8 Ohms
Rext=6 Ohms
VOUT vs IOUT
VEN=3.3V
VOUT (V)
Rext=6 Ohms
VEN=3.3V
25°C
Rext (Ohms)vs IOUT
85°C
-40°C
Rext= 20 Ohms
VEN=3.3V
85°C
25°C
-40°C
VOUT=2V
Rext= 60 Ohms Rext= open
Rext= 30 Ohms
Rext=10 Ohms
Rext=8 Ohms
Rext=6 Ohms
VEN (V)
BCR421UW6Q
Document number: DS38302 Rev. 1 - 2
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BCR421UW6Q
Typical Electrical Characteristics (Cont.) (@TA = +25°C, unless otherwise specified.)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
0.000
0.005
0.010
0.015
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
0.0
500.0µ
1.0m
1.5m
2.0m
2.5m
3.0m
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
0.00
0.05
0.10
0.15
0.20
Rext= open
VOUT=2V
85°C
25°C
-40°C
IOUT (A)
IOUT (A)
VEN (V) VEN (V)
VEN (V)
VEN (V)
Rext= open
85°C
25°C -40°C
IOUT (A)
IOUT = 0A
IEN (mA)
VENvs IOUT
VENvs IOUT
VENvs IOUT
Rext=6 Ohms
VOUT=2V
25°C
VENvs IEN
85°C
-40°C
Rext= 20 Ohms
VOUT=2V
85°C
25°C
-40°C
BCR421UW6Q
Document number: DS38302 Rev. 1 - 2
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BCR421UW6Q
Application Information
Figure 1 Typical Application Circuit for
Linear Mode Current Sink LED Driver
Figure 2 Application Circuit for Increasing LED Current
The BCR421 is designed for driving low current LEDs with typical LED
currents of 10mA to 350mA. They provide a cost-effective way for
driving low current LEDs compared with more complex switching
regulator solutions. Furthermore, they reduce the PCB board area of the
solution as there is no need for external components like inductors,
capacitors and switching diodes.
Figure 1 shows a typical application circuit diagram for driving an LED
or string of LEDs. The device comes with an internal resistor (RINT) of
typically 95, which in the absence of an external resistor, sets an LED
current of 10mA (typical) from a VEN = 3.3V and VOUT = 1.4V for
BCR421. LED current can be increased to a desired value by choosing
an appropriate external resistor, REXT.
The REXT Vs IOUT graphs should be used to select the appropriate
resistor. Choosing a low tolerance REXT will improve the overall
accuracy of the current sense formed by the parallel connection of RINT
and REXT.
Two or more BCR421s can be connected in parallel to construct higher
current LED strings as shown in Figure 2. Consideration of the expected
linear mode power dissipation must be factored into the design, with
respect to the BCR421’s thermal resistance. The maximum voltage
across the device can be calculated by taking the maximum supply
voltage and subtracting the voltage across the LED string.
VOUT = VS VLED
PD = (VOUT × ILED) + (VEN × IEN)
As the output current of BCR421 increases, it is necessary to provide
appropriate thermal relief to the device. The power dissipation
supported by the device is dependent upon the PCB board material, the
copper area and the ambient temperature. The maximum dissipation
the device can handle is given by:
PD = ( TJ(MAX) - TA) / RθJA
Refer to the thermal characteristic graphs on Page 4 for selecting the
appropriate PCB copper area.
BCR421UW6Q
Document number: DS38302 Rev. 1 - 2
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BCR421UW6Q
Application Information (Continued)
PWM dimming can be achieved by driving the EN pin. Dimming is achieved by turning the LEDs ON and OFF for a portion of a single cycle. The
PWM signal can be provided by a micro-controller or analog circuitry; typical circuit is shown in Figure 3. Figure 4 is a typical response of LED
current vs. PWM duty cycle on the EN pin.
Figure 3 Application Circuits for LED Driver with PWM Dimming Functionality
Figure 4 Typical LED Current Response vs. PWM Duty Cycle for
400Hz PWM Frequency
BCR421UW6Q
Document number: DS38302 Rev. 1 - 2
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Application Information (Cont.)
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
diode with a low VF in line with the driver/LED combination. The low
VF increases the available voltage to the LED stack and dissipates
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,
providing exceptionally low VF for its package size of 1mm x 0.6mm.
Other reverse voltage ratings are available from Diodes
Incorporateds website such as the SBR02U100LP (0.2A/100V) or
SBR0220LP (0.2A/20V).
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.
The BAS40BRW incorporates four low VF Schottky diodes in a
single package, reducing the power dissipated and maximizes the
voltage across the LED stack.
Figure 7 shows an example configuration for 350mA operation. In
such higher current configurations adequate enable current is
provided by increasing the enable voltage.
Figure 5 Application Circuit for LED Driver
with Reverse Polarity Protection
Figure 6 Application Circuit for LED Driver with
Assured Operation Regardless of Polarity
Figure 7 Example for 350mA operation
BCR421UW6Q
Document number: DS38302 Rev. 1 - 2
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BCR421UW6Q
Package Outline Dimensions
Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for the latest version.
Suggested Pad Layout
Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version.
a1
D
e
E1 E
b
A2 A1
Seating Plane
L
c
a
e1
A3
SOT26 (SC74R)
Dim
Min
Max
Typ
A1
0.013
0.10
0.05
A2
1.00
1.30
1.10
A3
0.70
0.80
0.75
b
0.35
0.50
0.38
c
0.10
0.20
0.15
D
2.90
3.10
3.00
e
-
-
0.95
e1
-
-
1.90
E
2.70
3.00
2.80
E1
1.50
1.70
1.60
L
0.35
0.55
0.40
a
-
-
a1
-
-
All Dimensions in mm
Dimensions
Value (in mm)
C
2.40
C1
0.95
G
1.60
X
0.55
Y
0.80
Y1
3.20
C1
Y1 G
X
Y
C
SOT26 (SC74R)
SOT26 (SC74R)
BCR421UW6Q
Document number: DS38302 Rev. 1 - 2
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© Diodes Incorporated
BCR421UW6Q
IMPORTANT NOTICE
DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
(AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION).
Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes
without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the
application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or
trademark rights, nor the rights of others. Any Customer or user of this document or products described herein in such applications shall assume
all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on Diodes Incorporated
website, harmless against all damages.
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Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall indemnify and
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indirectly, any claim of personal injury or death associated with such unintended or unauthorized application.
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This document is written in English but may be translated into multiple languages for reference. Only the English version of this document is the
final and determinative format released by Diodes Incorporated.
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Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express
written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:
A. Life support devices or systems are devices or systems which:
1. are intended to implant into the body, or
2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the
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failure of the life support device or to affect its safety or effectiveness.
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