Infineon BCR420U, BCR421U Schematic [ru]

LED Driver

Features

BCR420U / BCR421U

• Continuous output current up to 150mA
with external resistor

• Suitable for supply voltages of 40V and above

• Low side current control, µC compatible

PWM input (BCR421U) up to 10kHz

• Up to 1W power dissipation in a small SC74 package

• Negative thermal coefficient reduces output current

at higher temperatures

• Easy paralleling of drivers to increase current

• Pb-free (RoHS compliant) package

• Automotive qualified according AEC Q101

Applications

• Architectural LED lighting

• Channel letters for advertising, LED strips for decorative lighting

• Retail lighting in fridge, freezer case and vending machines

4

5

6

3

2

1

• Emergency lighting (e.g. steps lighting, exit way signs etc.)

• Ship, train and aircraft interior illumination

General Description

The BCR420U/BCR421U provide a low-cost solution for driving 0.25W LEDs with a typical
LED current ILED of 75mA to 150mA. Internal breakdown voltage is >40V, this is the
maximum voltage that the LED driver IC can sustain when connected to it directly.
The BCR420U/BCR421U can be operated at supply voltages of 40V or higher, by simply
stacking a series of LEDs in front of the LED drivers, resulting in a certain voltage drop
depending on the forward voltages of the LEDs, reducing the voltage at the supply pin
of the driver below 40V. A digital input pin (BCR421U) allows dimming via a Microcontroller
with frequencies of up to 10 kHz. A reduction of the output current at higher temperatures
is the result of the negative thermal coefficient of 0.2% /K. of the LED drivers.
With no need for additional external components like inductors, capacitors and
free wheeling diodes, the BCR420U/BCR421U LED drivers are a cost-efficient and
PCB-area saving solution for driving 0.25W LEDs.

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6 5 4

1 2 3

BCR420U / BCR421U

Typical ApplicationPin Configuration

+Vs

µC

I

EN IOUT

1

EN

OUT

2,3,5

Rext

6

Vdrop

GND

4

BCR421U

Type Marking Pin Configuration Package

BCR420U
BCR421U

40
41

1 = EN 2;3;5 =

OUT

4 = GND 6 = R

ext

SC74
SC74

Maximum Ratings
Parameter

Enable voltage
BCR420U
BCR421U

Output current
Output voltage

Reverse voltage between all terminals
Total power dissipation,

T

= 100 °C

S

Junction temperature

Symbol Value Unit

V

EN

V

40

4.5

I
V

V
P
T

out

out
R

tot

j

200 mA

38 V

0.5

1000 mW

150 °C

Storage temperature

Thermal Resistance
Parameter

Junction - soldering point

1

For calculation of

R

please refer to Application Note Thermal Resistance

thJA

1)

T

stg

-65 ... 150

Symbol Value Unit

R

thJS

2

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K/W

BCR420U / BCR421U

Electrical Characteristics at

T

=25°C, unless otherwise specified

A

Parameter

Characteristics

Collector-emitter breakdown voltage

I

= 1 mA,

C

I

B

= 0

Enable current

V

= 24 V , BCR420U

EN

V

= 3.3 V , BCR421U

EN

DC current gain

I

= 50 mA,

C

V

CE

= 1 V

Internal resistor

I

= 10 mA

Rint

Bias resistor
BCR420U

Symbol Values Unit

min. typ. max.

V

BR(CEO)

I

EN

h

FE

R

int

R

B

40 - - V

-

-

1.2

1.2

-

-

200 350 500 -

65 90 105 Ω

-

20

-

mA

kΩ

BCR421U
Output current

V
V
V

out
out
out

= 1.4 V,
= 1.4 V,
> 2.0 V,

V

= 24 V, BCR420U

EN

V

= 3.3 V, BCR421U

EN

V

= 24 V,

EN

R

EXT

= 5.1 Ω,

BCR420U

V

> 2.0 V,

out

V

EN

= 3.3 V,

R

EXT

= 5.1 Ω,

BCR421U
Voltage drop (

I

= 10mA

out

V

-

V

S

)

E

DC Characteristics with stabilized LED load

Lowest sufficient supply voltage overhead

I

> 18mA

out

Output current change versus

V

= 24 V;

EN

V

> 2.0 V, BCR420U

out

T

A

I

out

V

drop

V

Smin

∆

I

out/Iout

-

8
8

-

-

1.5

10
10

150

150

-

12
12

-

-

mA

0.85 0.95 1.05 V

- 1.4 - V

-

-0.2

%/K

-

V

= 3.3 V;

EN

V

> 2.0 V, BCR421U

out

Output current change versus

V
V

EN
EN

= 24 V;
= 3.3 V;

V

> 2.0 V, BCR420U

out

V

> 2.0 V, BCR421U

out

V

-

S

∆

I

out/Iout

-

-

3

-0.2

1
1

­%/V

-

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BCR420U / BCR421U

Total power dissipation

1200

mW

1000

900
800

tot

P

700
600
500
400
300
200
100

0

0 20 40 60 80 100 120

P

tot

= f (

T

)

S

Permissible Pulse Load

R

thJS

= f (

t

)

p

3

10

2

10

thJS

R

1

°C

T

10

0

10

-1

10

150

S

10

-6

10

-5

10

-4

10

-3

10

-2

D = 0,5
0,2
0,1
0,05
0,02
0,01
0,005
0

s

T

0

10

P

Permissible Pulse Load

P

totmax

/

P

totDC

= f (

t

)

p

3

10

-

totDC

P

/

2

10

totmax

P

1

10

0

10

10

-6

10

-5

10

-4

10

D = 0

0.005

0.01

0.02

0.05

0.1

0.2

0.5

-3

10

-2

s

T

0

10

P

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