CAT4201
350 mA High Efficiency
Step Down LED Driver
Description
The CAT4201 is a high efficiency step−down converter optimized to
drive high current LEDs. A patented switching control algorithm
allows highly efficient and accurate LED current regulation. A single
RSET resistor sets the full scale LED string current up to 350 mA from
supplies as high as 36 V.
The switching architecture of the CAT4201 results in extremely low
internal power dissipation allowing the device to be housed in a tiny
package without the need for dedicated heat sinking. The device is
compatible with switching frequencies of up to 1 MHz, making it ideal for
applications requiring small footprint and low value external inductors.
Analog dimming and LED shutdown control is provided via a single
input pin, CTRL. Additional features include overload current protection
and thermal shutdown. The device is available in 8−lead SOIC package
and the low profile 5−lead thin SOT23 package ideal for space
constrained applications.
Features
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5
8
1
1
SOIC−8**
V SUFFIX
CASE 751BD
TSOT−23
TD SUFFIX
CASE 419AE
PIN CONNECTIONS AND
MARKING DIAGRAMS
(Top Views)
1
CTRL
TFYM
GND
RSET
TSOT−23
TF = Specific Device Code
Y = Production Year (Last Digit)
M = Production Month: (1−9, O, N, D)
PGND
VBAT
SW
SW
1
4201A
AYMXXX
G
PGND
CTRL
GND
RSET
VBAT
•
•
•
•
•
•
•
•
•
•
LED Drive Current up to 350 mA
Compatible with 12 V and 24 V Standard Systems
Handles Transients up to 40 V
Single Pin Control and Dimming Function
Power Efficiency up to 94%
Drives LED Strings of up to 32 V
Open and Short LED Protection
Parallel Configuration for Higher Output Current
TSOT−23 5−lead and SOIC 8−lead Packages
These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
Compliant
SW
SOIC−8
4201A = Specific Device Code
A = Assembly Location
Y = Production Year (Last Digit)
M = Production Month: (1−9, O, N, D)
XXX = Last Three Digits of Assembly Lot Number
G
= Pb−Free Package
Applications
•
12 V and 24 V Lighting Systems
•
Automotive and Aircraft Lighting
•
General Lighting, High Brightness 350 mA LEDs
VBAT
9V
C1
CAT4201
VBAT
RSET
CTRL
SW
GND
L
22
mH
D
C2
10
mF
ORDERING INFORMATION
300 mA
Device
CAT4201TD−GT3
CAT4201V−GT3**
Package
TSOT−23
(Pb−Free)
SOIC−8
(Pb−Free)
Shipping
3,000/
Tape & Reel
3,000/
Tape & Reel
4.7
mF
R1
10 kW
D: ON Semiconductor MBR0540
L: Sumida CDRH6D26−220
See Table 4 on page 6 for external component selection.
* Plated Finish: NiPdAu
** For availability, contact factory
Figure 1. Typical Application Circuit
©
Semiconductor Components Industries, LLC, 2011
May, 2011
−
Rev. 8
1
Publication Order Number:
CAT4201/D
CAT4201
Table 1. ABSOLUTE MAXIMUM RATINGS
Parameters
VBAT, SW, CTRL
RSET
Switch SW peak current
Storage Temperature Range
Junction Temperature Range
Lead Temperature
Ratings
−0.3
to +40
−0.3
to +5
1
−65
to +160
−40
to +150
300
Units
V
V
A
_C
_C
_C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
Table 2. RECOMMENDED OPERATING CONDITIONS
Parameters
VBAT voltage (Notes 1, 2)
SW voltage
Ambient Temperature Range
LED Current
Switching Frequency
Ratings
6.5 to 36 (Note 1)
0 to 36
−40
to +125
50 to 350
50 to 1000
Units
V
V
_C
mA
kHz
1. The VBAT pin voltage should be at least 3 V greater than the total sum of the LED forward voltages in order to operate at nominal LED current.
2. During power−up, the slew rate of the input supply should be greater than 1
ms
for every 5 V increase of VBAT.
Table 3. ELECTRICAL CHARACTERISTICS
(V
IN
= 13 V, ambient temperature of 25°C (over recommended operating conditions unless otherwise specified))
Symbol
I
Q
I
SD
V
FB
I
LED
Parameter
Operating Supply Current on VBAT pin
Idle Mode Supply Current on VBAT pin
RSET Pin Voltage
Programmed LED Current
CTRL = GND
2 LEDs with I
LED
= 300 mA
R1 = 33 kW
R1 = 10 kW
R1 = 8.25 kW
1.15
270
Conditions
Min
Typ
0.4
90
1.2
100
300
350
2.6
LED enable voltage threshold
LED disable voltage threshold
V
CTRL
= 3 V
V
CTRL
= 12 V
I
SW
= 300 mA
0.4
0.9
0.9
40
200
0.9
150
20
Typical Application Circuit
86
80
1.5
1.25
330
3.1
1.2
Max
1
Units
mA
mA
V
mA
V
CTRL−FULL
V
CTRL−EN
V
CTRL−SD
I
CTRL
R
SW
T
SD
T
HYST
h
CTRL Voltage for 100% Brightness
CTRL Voltage to Enable LEDs
CTRL Voltage to Shutdown LEDs
CTRL pin input bias
Switch “On” Resistance
Thermal Shutdown
Thermal Hysteresis
Efficiency
V
V
V
mA
W
°C
°C
%
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2
CAT4201
TYPICAL OPERATION CHARACTERISTICS
(V
IN
= 13 V, I
LED
= 300 mA, L = 22
mH,
C
1
= 4.7
mF,
C
2
= 10
mF,
T
AMB
= 25°C unless otherwise specified)
1.0
QUIESCENT CURRENT (mA)
0.8
0.6
0.4
0.2
0
IDLE CURRENT (mA)
8
10
12
14
16
18
20
22
200
150
100
50
24
0
0
4
8
12
16
20
24
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Figure 2. Input Operating Supply Current
250
CTRL BIAS CURRENT (mA)
200
150
100
50
0
RSET VOLTAGE (V)
1.30
Figure 3. Idle Mode Supply Current
(CTRL = 0 V)
V
IN
= 13 V
1.25
1.20
1.15
0
2
4
6
8
10
12
1.10
−40
0
40
TEMPERATURE (°C)
80
120
CTRL VOLTAGE (V)
Figure 4. CTRL Input Bias Current
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
1
2
CTRL VOLTAGE (V)
3
4
0
5
+25°C
−40°C
+85°C
LED CURRENT (mA)
RSET VOLTAGE (V)
300
400
Figure 5. RSET Voltage vs. Temperature
200
100
10
15
20
RSET (kW)
25
30
35
Figure 6. RSET Voltage vs. CTRL Voltage
Figure 7. LED Current vs. RSET
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CAT4201
TYPICAL OPERATION CHARACTERISTICS
(V
IN
= 13 V, I
LED
= 300 mA, L = 22
mH,
C
1
= 4.7
mF,
C
2
= 10
mF,
T
AMB
= 25°C unless otherwise specified)
500
SWITCHING FREQUENCY (kHz)
SWITCHING FREQUENCY (kHz)
400
300
300 mA
200
100
0
150 mA
700
600
150 mA
500
400
300
200
100
0
8
12
16
20
24
28
300 mA
8
12
16
20
24
28
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Figure 8. Switching Frequency vs. Input
Voltage (1 LED)
500
SWITCHING FREQUENCY (kHz)
VIN = 13 V
SW RESISTANCE (W)
400
150 mA
1.6
1.2
0.8
0.4
0
2.0
Figure 9. Switching Frequency vs. Input
Voltage (2 LEDs)
300
300 mA
200
100
−40
0
40
TEMPERATURE (°C)
80
120
8
10
12
14
16
18
20
22
24
INPUT VOLTAGE (V)
Figure 10. Switching Frequency vs.
Temperature
100
95
EFFICIENCY (%)
EFFICIENCY (%)
90
85
80
75
70
150 mA
300 mA
100
95
90
Figure 11. Switch ON Resistance vs. Input
Voltage
150 mA
300 mA
85
80
75
70
8
10
12
14
16
18
20
22
24
8
10
12
14
16
18
20
22
24
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Figure 12. Efficiency vs. Input Voltage (1 LED)
Figure 13. Efficiency vs. Input Voltage
(2 LEDs)
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4
CAT4201
TYPICAL OPERATION CHARACTERISTICS
(V
IN
= 13 V, I
LED
= 300 mA, L = 22
mH,
C
1
= 4.7
mF,
C
2
= 10
mF,
T
AMB
= 25°C unless otherwise specified)
100
95
EFFICIENCY (%)
90
85
80
75
70
1 LED
2 LEDs
LED CURRENT VARIATION (%)
10
8
6
4
2
0
−2
−4
−6
−8
−10
−40
VIN = 13 V
100
150
200
250
300
350
0
40
TEMPERATURE (°C)
80
120
LED CURRENT (mA)
Figure 14. Efficiency vs. LED Current
350
300
LED CURRENT (mA)
250
200
150
100
50
0
0
4
8
12
16
20
24
28
V
F
= 3.1 V
150 mA
V
F
= 3.3 V
300 mA
LED CURRENT (mA)
350
300
250
200
150
100
50
0
0
Figure 15. LED Current Regulation vs.
Temperature
V
F
= 3.3 V
300 mA
V
F
= 3.1 V
150 mA
4
8
12
16
20
24
28
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Figure 16. LED Current vs. Input Voltage
(1 LED)
Figure 17. LED Current vs. Input Voltage
(2 LEDs)
SW
5V/div
CTRL
5V/div
Inductor
Current
200mA/
div
LED
Current
200mA/
div
2
ms/div
40
ms/div
Figure 18. Switching Waveforms
Figure 19. CTRL Power−up
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