BCR405UW6Q
Document number: DS38940 Rev. 1 – 2
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BCR405UW6Q
50 to 100mA LED CONSTANT CURRENT REGULATOR in SOT26
Description
This Linear LED driver is designed to meet the stringent requirements
of automotive applications.
The BCR405UW6 monolithically integrates a transistor, diodes and
resistors to function as a Constant Current Regulator (CCR) for LED
driving. The device regulates with a preset 50mA nominal that can be
adjusted with external resistor up to 100mA. 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 then it can be used in applications with supply voltages up to
40V.
With no need for additional external components, this CCR is fully
integrated into a SOT26 minimizing PCB area and component count.
Applications
Constant current regulation (CCR) in automotive LED lighting:
Interior and Exterior Automotive LED Lighting
Dome and Mood Lighting
Puddle Lighting
Side Marker Lights
Features
LED Constant Current Regulator Using PNP Emitter-Follower with
Emitter Resistor to Current Limit
IOUT = 50mA ± 10% constant current (Preset)
IOUT up to 100mA adjustable with an external resistor
VS – 40V Supply Voltage
PD up to 1W in SOT26/ SC74R
LED dimming using PWM up to 25kHz
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)
Ordering Information (Note 5)
Product
Marking
Reel size (inches)
Tape width (mm)
Quantity per reel
BCR405UW6Q-7
405
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
5. For packaging details, go to our website at http://www.diodes.com/products/packages.html.
Pin Name
Pin Function
Vs
Supply Voltage
OUT
Regulated Output Current
Rext
External Resistor for
Adjusting Output Current
GND
Power Ground
Top View
Pin-Out
SOT26 (SC-74)
Top View
Internal Device
Schematic
GND
OUT
OUT
Rext
VS
OUT
BCR405UW6Q
Document number: DS38940 Rev. 1 – 2
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BCR405UW6Q
Marking Information
Date Code Key
Year
2016
2017
2018
2019
2020
2021
2022
Code
D
E
F
G
H
I
J
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
Supply Voltage
VS
40
V
Output Current
IOUT
100
mA
Output Voltage
Vout
40
V
Reverse voltage between all terminals
VR
0.5
V
Thermal Characteristics
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
Unit
JEDEC Class
Electrostatic Discharge – Human Body Model
ESD HBM
800
V
1B
Electrostatic Discharge – Machine Model
ESD MM
300
V
B
Notes: 6. For a device mounted with the OUT leads on 50mm x 50mm 2oz 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 15mm x 15mm 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.
405 = Part Marking (See Ordering Information)
YM = Date Code Marking
Y = Year (ex: C = 2016)
M = Month (ex: 9 = September)
405
SOT26 (SC-74)
BCR405UW6Q
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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
GND (Enable) Current
IGND
340
420
500
µA
VS = 10V; VOUT = open
GND (Enable) Current
IGND
-
380
-
µA
VS = 10V; VOUT = 8.6V
DC Current Gain
hFE
100
220
470
-
IC = 50mA; VCE = 1V
Internal Resistor
Rint
13
16.5
22
Ω
IRint = 50mA
Output Current (nominal)
IOUT
45
50
55
mA
Vout = 8.6V; VS = 10V
Voltage Drop (VRext)
Vdrop
-
0.83
-
V
IOUT = 50mA
Lowest Sufficient Supply Voltage (VS-
VOUT)
VSmin
-
1.4
-
V
IOUT > 18mA
Output Current Change
Vs. Temperature
ΔIOUT/IOUT
-
-0.25
-
%/°C
VS = 10V
Output Current Change
Vs. Supply Voltage
ΔIOUT/IOUT
-
1.5
-
%/V
VS = 10V
BCR405UW6Q
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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)
BCR405UW6Q
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Typical Electrical Characteristics (continued) (@TA = +25°C, unless otherwise specified.)
0 5 10 15 20 25 30 35 40
20
40
60
20 40 60 80 100
30
40
50
60
70
80
510 15 20 25 30 35 40
1
20
40
60
80
-25 0 25 50 75 100 125 150
20
30
40
50
60
70
80
0 5 10 15 20 25 30 35 40
0
20
40
60
80
0 5 10 15 20 25 30 35 40
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
VS-VOUT=1.4V to 2V
VS-VOUT=1V
VS=10V
VS-VOUT=1.4V
150°C
85°C
25°C
-40°C
VS-VOUT=1.4V
IS (mA) IOUT (mA)
IOUT (mA) IOUT (mA)
IOUT (mA)
IOUT (mA)
Rext= 56 Ohms
VS vs IS
VS (V)
VS vs IOUT
VS vs IOUT
VS (V)
TJ vs IOUT
TJ (°C)
Rext (Ohms)
Rext=24 Ohms
Rext= 82 Ohms
Rext=56 Ohms
Rext=40 Ohms Rext=Open
VS vs IOUT
VS-VOUT=1.4V
VS (V)
Rext=24 Ohms
Rext=82 Ohms
Rext=40 Ohms
Rext (Ohms)vs IOUT
VS=10V
150°C
Rext= OPEN
VS-VOUT=1.4V Rext= OPEN
85°C
25°C
-40°C
85°C
25°C -40°C
VS (V)
BCR405UW6Q
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Application Information
Figure 1. Typical Application Circuit for
BCR40X LED Driver
Figure 2. Application Circuit for Increasing LED Current
The BCR401/2/5 are designed for driving low current LEDs with typical
LED currents of 10mA to 100mA. 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 devices come with an internal resistor (RINT) of
typically 91Ω, 20Ω, 16.5Ω which in the absence of an external resistor,
sets an LED current of 10mA, 20mA, 50mA respectively. 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.
The negative temperature coefficient of the BCR series allows easy
paralleling of BCR410/2/5s. In applications where current sharing is
required either due to high current requirements of LED strings or for
power sharing, two or more BCR401/2/5s can be connected in parallel
as shown in Figure 2. Power dissipation capability must be factored into
the design, with respect to the BCR401/2/5’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.
VDEVICE = VS – VOUT
PD = (VDEVICE × ILED) + (VS × IGND)
As the output current of BCR401/2/5 increases, it is necessary to
connect an appropriate heat sink to the OUT pins of 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 in datasheet for selecting the
appropriate PCB copper area.
BCR405UW6Q
Document number: DS38940 Rev. 1 – 2
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Application Information (continued)
PWM is the most pursued method for LED dimming. In the PWM method, dimming is achieved by turning the LEDs ON and OFF for a portion of a
single cycle. PWM dimming can be achieved by enabling/disabling the LED driver itself (refer to Figure 3a ,3b) or by the switching the power path
on and off (refer to Figure 3c). The PWM signal can be provided by a micro-controller or analog circuitry; typical circuits are shown in Figure 3.
Figure 4 is a typical response of LED current vs. PWM duty cycle, PWM method showed in Figure 3b is used for generating the graphs.
Figure 3a Figure 3b
Figure 3c
Figure 3a, 3b & 3c. Application Circuits for LED Driver with PWM Dimming Functionality
BCR405UW6Q
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Application Information (cont.)
Figure: 4 Typical LED Current Response vs. PWM Duty Cycle for
25kHz, 10kHz and 1kHz PWM Frequency (refer to circuit 3b)
0
10
20
30
40
50
60
0 20 40 60 80 100
LED current (mA)
Duty ratio %
PWM resolution at 25kHz
calculated DC current
Measured DC current
0
10
20
30
40
50
60
0 20 40 60 80 100
LED current (mA)
Duty ratio %
PWM resolution at 10kHz
calculated DC current
Measured DC current
0
10
20
30
40
50
60
0 20 40 60 80 100
LED current (mA)
Duty ratio %
PWM resolution at 1kHz
calculated DC current
Measured DC current
BCR405UW6Q
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Application Information (cont.)
The error between the calculated theoretical value and the measured value is due to the turn on and turn off times of the BCR401/2/5. There will
be a small contribution from the switches (a pre-biased transistor or a MOSFET) shown in Figure 3a and 3b towards the total turn on and turn off
times of the BCR401/2/5. It is recommended to keep the external switching delays to the lowest possible value to improve PWM accuracy. The
typical switching times of the BCR401/2/5 for the configuration shown in Figure 3b are:
Turn on time = 200ns
Turn off time = 10µs
Please refer to the Figure 5 and 6 for the switching time performance. The percentage contribution of these switching delays increases with
increasing frequency and decreasing duty ratio as can be seen in Figure 4.
Figure 5. Turn on time of BCR401/2/5 (PWM method shown in figure 3b)
Figure 6. Turn on time of BCR401/2/5 (PWM method shown in figure 3c)
However, where possible, the switching performance of the BCR401/2/5 can be significantly improved by switching the power path as shown in
Figure 3c. The resulting turn-off time is shown in Figure 7. This resulted in an improved PWM resolution at 25kHz as shown in Figure 8.
Turn-off time = ~200ns
BCR405UW6Q
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Application Information (cont.)
Figure 7. Turn off time of BCR401/2/5 while switching the power path as shown in figure 3c
Yellow PWM signal
Green LED current
Blue No connection made to this probe channel
Figure 8. PWM resolution with power path switching (refer to figure 3c)
0
10
20
30
40
50
60
0 20 40 60 80 100
LED current (mA)
Duty ratio %
PWM resolution at 25kHz
calculated DC current
Measured DC current
BCR405UW6Q
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Application Information (cont.)
To remove the potential for 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 9 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
Incorporated’s 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
10, 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 9. Application Circuit for LED Driver
with Reverse Polarity Protection
Figure 10. Application Circuit for LED Driver with
Assured Operation Regardless of Polarity
BCR405UW6Q
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Package Outline Dimensions
Please see http://www.diodes.com/package-outlines.html for the latest version.
Suggested Pad Layout
Please see http://www.diodes.com/package-outlines.html 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
-
-
8°
a1
-
-
7°
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)
BCR405UW6Q
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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
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application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or
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final and determinative format released by Diodes Incorporated.
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written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:
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