2009-07-31
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BCR405U
LED Driver
Features
• LED drive current of 50mA
• Output current adjustable up to 65mA with external resistor
• Supply voltage up to 40V
• Easy paralleling of drivers to increase current
• Low voltage overhead of 1.4V
• High current accuracy at supply voltage variation
• No EMI
• High power dissipation of 750mW
• Reduced output current at higher temperatures - Negative thermal coefficient of -0.2% / K
• RoHS compliant (pb-free) small and robust SC-74 package
• Qualified according to AEC Q101
Applications
• Channel letters for advertising, LED strips for decorative lighting
• Aircraft, tra in, ship illumination
• Retrofits for general lighting, white goods like refrigerator lighting
• Medical ligh ting
• Automotive applications like CHMSL and rear combination lights
54
63
2
1
General Description
The BCR405U is a cost efficient LED driver to drive low power LED’s. The advantages
towards resistor biasing are:
• homogenous light output despite varying forward voltages in different LED strings
• homogenous light output of LED’s despite voltage drop across long supply lines
• homogenous light output independent from supply voltage variations
• longer lifetime of the LED’s due to reduced output current at higher temperatures
(negative thermal coefficient)
The advantages towards discrete solutions are:
• lower assembly cost
• smaller form factor
• better quality due to less soldering points
• higher output current accuracy due to pretested LED drivers
Dimming is possible by using an external digital transistor at the ground pin.
The BCR405U can be operated at higher supply voltages by putting LED’s between the
power supply +VS and the power supply pin of the LED driver. You can find further details
in the application note AN097.
The BCR405U is a perfect fit for numerous low power LED applications by combining small
form factor with low cost. These LED drivers offer several advantages to resistors like
significantly higher current control at very low voltage drop ensuring high lifetime of LED’s.
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BCR405U
Pin Configuration Typical Application
BCR 405U
Vdrop
Rext
(optional)
4
6
2,3,51
+Vs
Is Iout
1
2
3
6
5
4
GND
Out
Out
Rext
Out
Vs
BCR405U
Type Marking Pin Configuration Package
BCR405U L5s 1 = GND 2;3;5 = Iout 4 = VS6 = Rext SC74
Maximum Ratings
Parameter Symbol Value Unit
Supply voltage
V
S40 V
Output current
I
out 65 mA
Output voltage
V
out 38 V
Reverse voltage between all terminals
V
R0.5
Total power dissipation,
T
S ≤ 125 °C
P
tot 750 mW
Junction temperature
T
j150 °C
Storage temperature
T
stg -65 ... 150
Thermal Resistance
Parameter Symbol Value Unit
Junction - soldering point1)
R
thJS 50 K/W
1For calculation of
R
thJA please refer to Application Note Thermal Resistance
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BCR405U
Electrical Characteristics at
T
A=25°C, unless otherwise specified
Parameter Symbol Values Unit
min. typ. max.
Characteristics
Collector-emitter breakdown voltage
I
C = 1 mA,
I
B = 0
V
BR(CEO) 40 - - V
Supply current
V
S = 10 V
I
S340 420 500 µA
DC current gain
I
C = 50 mA,
V
CE = 1 V
h
FE 100 220 470 -
Internal resistor
I
Rint = 50 mA
R
int 13 17 22 Ω
Output current
V
S = 10 V
I
out 45 50 55 mA
Voltage drop (
V
S -
V
E)
I
out = 50 mA
V
drop 0.75 0.8 0.85 V
DC Characteristics with stabilized LED load
Lowest sufficient battery voltage overhead
I
out > 18mA
V
Smin -1.4 - V
Output current change versus
T
A
V
S = 10 V ∆
I
out/
I
out --0.15 -%/K
Output current change versus
V
S
V
S = 10 V ∆
I
out/
I
out - 1 - %/V
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BCR405U
Total power dissipation
P
tot =
f
(
T
S)
020 40 60 80 100 120 °C 150
T
S
0
100
200
300
400
500
600
700
800
mW
1000
P
tot
Permissible Pulse Load
R
thJS =
f
(
t
p)
10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 0
s
t
p
-1
10
0
10
1
10
2
10
K/W
R
thJS
0.5
0.2
0.1
0.05
0.02
0.01
0.005
D = 0
Permissible Pulse Load
P
totmax /
P
totDC =
f
(
t
p)
10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 0
s
t
p
0
10
1
10
2
10
3
10
-
P
totmax
/ P
totDC
D = 0
0.005
0.01
0.02
0.05
0.1
0.2
0.5
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BCR405U
Output current versus supply voltage
I
out =
f
(
V
S);
R
ext = Parameter
V
S -
V
out = 1.4 V
0 5 10 15 20 25 30 35 V45
V
S
-2
10
-1
10
A
I
out
56 Ohm
82 Ohm
open
Output current versus supply voltage
I
out = ƒ(
V
S),
T
A = 20°C
V
S -
V
out as Parameter
0 5 10 15 20 25 30 35 V45
V
S
-2
10
-1
10
A
I
out
1 V
1.2V - 2V
Supply current versus supply voltage
I
S =
f
(
V
S)
T
A = Parameter
0 5 10 15 20 25 30 35 40 V50
VS
0
0.0002
0.0004
0.0006
0.0008
0.001
0.0012
0.0014
0.0016
A
0.002
IS
80°C
20°C
-40°C
Output current versus supply voltage
I
out = ƒ(
V
S),
V
S
-
V
out
= 1.4 V
T
A = Parameter
0 5 10 15 20 25 30 35 V45
V
S
-2
10
-1
10
A
I
out
-40°C
20°C
80°C
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BCR405U
Output current versus external resistor
I
out = (
R
ext),
V
S = 10V,
V
S -
V
out = 1.4 V
T
A = Parameter
10 1 10 2
R
ext
-2
10
-1
10
A
I
out
-40°C
20°C
80°C
Output current
I
out (
T
S),
V
S = 10V,
V
S -
V
out = 1.4 V
REXT = Parameter
-50 -25 025 50 75 100 °C 150
T
S
0
10
20
30
40
50
mA
70
I
out
open
56 Ohm
Reference Voltage (Vdrop)
versus
I
out = 10 mA ... 65 mA
Reference Voltage (Vdrop)
versus
I
out = 10 µA ... 10 mA
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BCR405U
Application circuit:
Stand alone current source Application circuit:
Boost mode current source with
external power transistor
BCR 405U
Vdrop
Rext
(optional)
4
6
2,3,51
+Vs
Is Iout
BCR 405U
Vdrop
4
6
2,3,51
+Vs
Is Iout
ILED
R1
R2
Rext
(optional)
Application hints
BCR405U serves as an easy to use constant current source for LEDs. In stand alone
application an external resistor can be connected to adjust the current from 50 mA to 65 mA.
Rext can be determined by using the diagram 'Output current versus external resistor',
or by refering to diagram 'Reference voltage versus output current'. Look for your desired
output current on the x axis and read out the corresponding Vdrop. Calculate Rext:
Rext = Vdrop / (Iout -(Vdrop/Rint))
Please take into account that the resulting output currents will be slightly lower due to the
self heating of the component and the negative thermal coefficient.
In boost mode configuration the LED current can be extended to drive high power LEDs.
Select the power trasistor according the power dissipation and output current requirements.
(e.g. BC817SU or BCX68-25, etc.) Dimension R2 to reduce the transistor current transfer
ratio to 20 ... 50. For ILED / Iout =50 e.g. ILED= 350 mA, Iout is 7 mA.
R2 = VbeON / Iout.
Dimension R1 for minimum supply voltage condition:
R1 = (Vsmin -1.4V -VbeON)/ Iout.
Please visit our web site for application notes: www.infineon.com/lowcostleddriver
• AN077 gives hints to thermal design
• AN097 helps in case of high supply voltages
• AN101 gives an overview to LED biasing
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BCR405U
SC74 Package
Package Outline
Foot Print
Standard Packing
0.5
0.95
1.9
2.9
546
321
1.1 MAX.
(0.35)
(2.25)
±0.2
2.9 B
0.2
+0.1
-0.05
0.35
Pin 1
marking MB6x
0.95
1.9
0.15-0.06
+0.1
1.6
10˚ MAX.
A
±0.1
2.5
0.25
10˚ MAX.
±0.1
±0.1
A0.2 M
0.1 MAX.
2.7
4
3.15
Pin 1
marking
8
0.2
1.15
Reel ø180 mm = 3.000 Pieces/Reel
Reel ø330 mm = 10.000 Pieces/Reel
For symmetric types no defined Pin 1 orientation in reel.
Manufacturer
2005, June
Date code (Year/Month)
BCW66H
Type code
Pin 1 marking
Laser marking
Marking Layout (Example)
Small variations in positioning of
Date code, Type code and Manufacture are possible.
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BCR405U
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 2007.
All Rights Reserved.
Attention please!
The information given in this data sheet shall in no event be regarded as a guarantee
of conditions or characteristics (“Beschaffenheitsgarantie”). With respect to any
examples or hints given herein, any typical values stated herein and/or any information
regarding the application of the device, Infineon Technologies hereby disclaims any
and all warranties and liabilities of any kind, including without limitation warranties of
non-infringement of intellectual property rights of any third party.
Information
For further information on technology, delivery terms and conditions and prices
please contact your nearest Infineon Technologies Office (www.infineon.com).
Warnings
Due to technical requirements components may contain dangerous substances.
For information on the types in question please contact your nearest
Infineon Technologies Office.
Infineon Technologies Components may only be used in life-support devices or
systems with the express written approval of Infineon Technologies, if a failure of
such components can reasonably be expected to cause the failure of that
life-support device or system, or to affect the safety or effectiveness of that
device or system.
Life support devices or systems are intended to be implanted in the human body,
or to support and/or maintain and sustain and/or protect human life. If they fail,
it is reasonable to assume that the health of the user or other persons
may be endangered.
