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Número de pieza | TH1200F | |
Descripción | 350mA High Efficiency Step Down LED Driver | |
Fabricantes | Zetex Semiconductors | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de TH1200F (archivo pdf) en la parte inferior de esta página. Total 15 Páginas | ||
No Preview Available ! TH1200F
350mA High Efficiency Step Down LED Driver
FEATURES
LED drive current up to 350mA
Compatible with 12V and 24V standard systems
Handles transients up to 40V
Single Pin Control and Dimming function
Power Efficiency up to 94%
Drives LED strings of up to 32V
Open and short LED protection
Parallel configuration for higher output current
RoHS-compliant TSOT-23 5-lead package
APPLICATIONS
12V and 24V Lighting Systems
Automotive and Aircraft Lighting
General lighting
High Brightness 350mA LEDs
ORDERING INFORMATION
Part Number
TH1200F-YE-ML1
Quantity
per Reel
3000
* Plated Finish: NiPdAu
PIN CONFIGURATION
Package
Marking
TFxx
TSOT-23 5-lead
CTRL 1
5 VBAT
GND 2
RSET 3
4 SW
(Top View)
DESCRIPTION
The TH1200F 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
350mA from supplies as high as 36V.
The switching architecture of the TH1200F 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 1MHz,
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 the low
profile 5-lead thin SOT23 package and is ideal for
space constrained applications.
For Ordering Information details, see page 14.
TYPICAL APPLICATION CIRCUIT
Bulb Replacement
VBAT
9V C1
4.7µF
R1
10kΩ
VBAT
TH1200F
RSET
CTRL
SW
GND
D C2
10µF
L
22µH
300mA
D: Central Schottky CMDSH05-4
L: Sumida CDRH6D26-220
See Table 1 on page 6 for external component selection.
1
1 page TH1200F
Typical Operation Characteristics
VIN = 13V, ILED = 300mA, L = 22μH, C1= 4.7μF, C2 = 10μF, TAMB = 25°C unless otherwise specified
Efficiency vs. LED Current
100
95
2 LEDs
90
85
80
1 LED
75
70
100
150 200 250 300
LED CURRENT [mA]
350
LED Current Regulation vs. Temperature
10
8
6
4
2
0
-2
-4
-6
-8
-10
-40
VIN = 13V
0 40 80
TEMPERATURE [°C]
120
LED Current vs. Input Voltage (1 LED)
350
300 VF = 3.3V
300mA
250
200
150 VF = 3.1V
150mA
100
50
0
0 4 8 12 16 20 24 28
INPUT VOLTAGE [V]
Switching Waveforms
LED Current vs. Input Voltage (2 LEDs)
350
VF = 3.3V
300
300mA
250
200
VF = 3.1V
150
150mA
100
50
0
0 4 8 12 16 20 24 28
INPUT VOLTAGE [V]
CTRL Power-up
5
5 Page Operation from high supply voltage above 14V
For operation from a supply voltage above 14V, it is
recommended to have a slew rate of 1µs or more for
every 5V increase in VBAT supply. When using a high
supply voltage of 24V, a 1Ω or 2Ω resistor in series
with the supply, as shown on Figure 7, is
recommended to limit the slew rate of the supply
voltage. A 4.7µF minimum ceramic capacitor is placed
between the VBAT pin and ground. The combination
of the series resistor R3 and input capacitor C1 atcs
as a low pass filter limiting the excessive in-rush
currents and overvoltage transients which would
otherwise occur during “hot-plug” conditions, thereby
protecting the TH1200F driver.
VBAT R3
24V 1Ω C1
4.7µF
R1
10kΩ
VBAT
TH1200F
RSET
CTRL
SW
GND
D1 C2
4.7µF
L
33µH
R1
300mA
1kΩ
Figure 7. 24V Application with 5 LEDs
Operation from high supply voltage of 36V
When powering from a high supply voltage of 36V, a
2Ω resistor in series with the supply is recommended,
as shown on Figure 8, to limit the slew rate of the
supply voltage.
VBAT R3
36V 2Ω C1
4.7µF
R1
10kΩ
VBAT
TH1200F
RSET
CTRL
SW
GND
D1 C2
2.2µF
L
47µH
R2
300mA
1kΩ
Figure 8. 36V Application with 6 LEDs
TH1200F
Parallel configuration for driving LEDs beyond
350mA
Several TH1200F devices can be connected in
parallel for driving LEDs with current in excess of
350mA. The TH1200F driver circuits are connected to
the same LED cathode. Figure 9 shows the
application schematic for driving 1A into one LED with
three TH1200F connected in parallel. Each TH1200F
is driving the LED with a current set by its RSET
resistor. The resulting LED current is equal to the sum
of each driver current.
VIN R5
1Ω C1
4.7µF
R1
8.3kΩ
U1
VBAT
TH1200F
RSET
CTRL
SW
GND
D1
L1
22µH
C4
10µF
1A
R4
1kΩ
C2
4.7µF
R2
8.3kΩ
U2
VBAT
TH1200F
RSET
CTRL
SW
GND
D2
L2
22µH
C3
4.7µF
R3
8.3kΩ
U3
VBAT
TH1200F
RSET
CTRL
SW
GND
D3
L3
22µH
Figure 9. Three TH1200F in Parallel for 1A LED
11
11 Page |
Páginas | Total 15 Páginas | |
PDF Descargar | [ Datasheet TH1200F.PDF ] |
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