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Zetex Semiconductors |
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
TH1200F
Absolute Maximum Ratings(1)
0F
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
Recommended Operating Conditions
Parameters
VBAT voltage (2) (3)
SW voltage
Ambient Temperature Range
LED Current
Switching Frequency
Ratings
6.5 to 36 (2)
0 to 36
-40 to +125
50 to 350
50 to 1000
Units
V
V
°C
mA
kHz
ELECTRICAL CHARACTERISTICS
VIN = 13V, ambient temperature of 25ºC (over recommended operating conditions unless specified otherwise)
Symbol
IQ
Parameter
Operating Supply Current on
VBAT pin
Conditions
Min Typ Max Units
0.4 1 mA
ISD
Idle Mode Supply Current on
VBAT pin
CTRL = GND
90 µA
VFB RSET Pin Voltage
ILED Programmed LED Current
2 LEDs with ILED= 300mA
R1 = 33kΩ
R1 = 10kΩ
R1 = 8.25kΩ
1.15 1.2 1.25 V
100
270 300 330 mA
350
VCTRL-FULL
CTRL Voltage for 100%
Brightness
2.6 3.1 V
VCTRL-EN
CTRL Voltage to Enable
LEDs
LED enable voltage threshold
0.9 1.2
V
VCTRL-SD
ICTRL
RSW
TSD
THYST
η
CTRL Voltage to Shutdown
LEDs
CTRL pin input bias
Switch “On” Resistance
Thermal Shutdown
Thermal Hysteresis
Efficiency
LED disable voltage threshold
VCTRL = 3V
VCTRL = 12V
ISW = 300mA
Typical Application Circuit
0.4 0.9
V
40 80 µA
200
0.9 1.5 Ω
150 ºC
20 ºC
86 %
Notes:
(1) Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions outside of those listed in the operational sections of this
specification is not implied. Exposure to any absolute maximum rating for extended periods may affect device performance and reliability.
(2) The VBAT pin voltage should be at least 3V greater than the total sum of the LED forward voltages in order to operate at nominal LED
current.
(3) During power-up, the slew rate of the input supply should be greater than 1µs for every 5V increase of VBAT.
2
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