LT3743IUFD#PBF Linear Technology, LT3743IUFD#PBF Datasheet
LT3743IUFD#PBF
Specifications of LT3743IUFD#PBF
Available stocks
Related parts for LT3743IUFD#PBF
LT3743IUFD#PBF Summary of contents
Page 1
... FB pin. Overcurrent protection is provided and set by the CTRL_H pin. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 7199560, 7321203 and others pending ...
Page 2
... EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL LT3743EUFD#PBF LT3743EUFD#TRPBF LT3743IUFD#PBF LT3743IUFD#TRPBF LT3743EFE#PBF LT3743EFE#TRPBF LT3743IFE#PBF LT3743IFE#TRPBF Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. ...
Page 3
ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T otherwise noted. PARAMETER Input Voltage Range V Pin Quiescent Current (Note 3) IN Non-Switching Operation Shutdown Mode EN/UVLO Pin Falling Threshold EN/UVLO Hysteresis EN/UVLO Pin Current PWM Pin Threshold CTRL_SEL ...
Page 4
LT3743 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T PARAMETER PWMG Control Signals CTRL_SEL High to PWMGL Low Delay CTRL_SEL High to PWMGH High Delay CTRL_SEL Low to PWMGH Low Delay CTRL_SEL Low to PWMGL High Delay PWMGH ...
Page 5
TYPICAL PERFORMANCE CHARACTERISTICS EN/UVLO Threshold (Falling) 1.70 1.64 1.58 –50°C 1.52 130°C 1.46 1. (V) IN 3743 G01 Quiescent Current (Non-Switching) 2.0 1.6 1.2 0.8 0 25° 130°C A ...
Page 6
LT3743 TYPICAL PERFORMANCE CHARACTERISTICS Internal UVLO 5.0 4.5 4.0 3.5 3.0 –50 – TEMPERATURE (°C) 3743 G10 V Load Reg at 12V CC_INT 6.0 5.6 5.2 4.8 4.4 4 (mA) ...
Page 7
TYPICAL PERFORMANCE CHARACTERISTICS PWM Driver R DS(0N PMOS 3 2 NMOS 1 0 –50 – TEMPERATURE (°C) 3743 G19 Non-Overlap PWM Signal Delay 150 140 PWMGL TO PWMGH 130 PWMGH TO PWMGL 120 110 100 ...
Page 8
LT3743 TYPICAL PERFORMANCE CHARACTERISTICS Overcurrent Threshold 120 100 0.75 1.5 2.25 CTRL_H (V) 3743 G28 LED Current Waveforms (3000: 20A CTRL_SEL 5V/DIV SW 10V/DIV I LED 11.1A/DIV 3743 G31 20μs/DIV Voltage Regulation ...
Page 9
PIN FUNCTIONS (QFN/TSSOP) GND (Pins 20, 21, Exposed Pad Pin 29/Pins 2, 7, 11, 22, 27, Exposed Pad Pin 29): Ground. The exposed pad must be soldered to the PCB. EN/UVLO (Pin 2/Pin 4): Enable Pin. The ...
Page 10
LT3743 PIN FUNCTIONS (QFN/TSSOP) PWMGL (Pin 22/Pin 23): The PWMGL output pin drives the gate of an external FET to connect one of the switching regulator output capacitors to the load. The driver pull-up impedance is 3.2Ω and pull-down impedance ...
Page 11
BLOCK DIAGRAM (QFN Package 402k EN/UVLO 2 133k V REF 3 2V REFERENCE 2.2nF SYNC SYNC 16 OSCILLATOR RT 15 82.5k 1.5V + 5.5μA CTRL_H + 6 CTRL_L + 7 – CTRL BUFFER SS 8 CTRL_T 100nF 4 ...
Page 12
LT3743 OPERATION The LT3743 utilizes fi xed frequency, average current mode control to accurately regulate the inductor current, independently from the output voltage. This is an ideal solution for applications requiring a regulated current source including driving high current LEDs ...
Page 13
APPLICATIONS INFORMATION Programming Inductor Current The analog voltage at the CTRL_L and CTRL_H pins is buffered and produces a reference voltage internal resistor. The regulated average inductor current is determined by: V CTRL • ...
Page 14
LT3743 APPLICATIONS INFORMATION Switching MOSFET Selection When selecting switching MOSFETs, the following pa- rameters are critical in determining the best devices for a given application: total gate charge ( gate to drain charge (Q DS(ON) charge (Q ), ...
Page 15
APPLICATIONS INFORMATION TOTAL 4 TRANSITIONAL OHMIC INPUT VOLTAGE (V) Figure 4a. Power Loss Example for M1 Whenever possible, utilize a switching MOSFET that minimizes the total gate charge to limit ...
Page 16
LT3743 APPLICATIONS INFORMATION V Capacitor Selection CC_INT The bypass capacitor for the V CC_INT than 5μF for stability and has no ESR requirement recommended that the ESR be lower than 50mΩ to reduce noise within the LT3743. For ...
Page 17
APPLICATIONS INFORMATION MOSFET Selection for the Switched Output Capacitors The MOSFETs used for the switched-output capacitor need to also handle the maximum regulated current while the capacitor is charged. The output drivers on the PWMGH and PWMGL pins have a ...
Page 18
LT3743 APPLICATIONS INFORMATION Voltage Regulation and Overvoltage Protection The LT3743 uses the FB pin to regulate the output to a maximum voltage and to provide a high speed overvoltage lockout to avoid high voltage conditions that may damage expensive high ...
Page 19
APPLICATIONS INFORMATION Thermal Shutdown The internal thermal shutdown within the LT3743 engages at 163°C and terminates switching, resets soft-start and shuts down the PWMGL and PWMGH drivers. When the part has cooled to 155°C, the internal reset is cleared and ...
Page 20
LT3743 APPLICATIONS INFORMATION Average Current Mode Control Compensation The use of average current mode control allows for precise regulation of the inductor and LED currents. Figure 16 shows the average current mode control loop used in the LT3743, where the ...
Page 21
TYPICAL APPLICATIONS EN/UVLO PWM CTRL_SEL 82.5k 2.2nF 50k R HOT 50k 499Ω R NTC 10k 10nF 4.7nF 12V, 20A LED Driver V EN/UVLO IN PWM 1μF 220μF CTRL_SEL 100nF SYNC L1 CBOOT 1.0μH 2.5mΩ V LT3743 SW ...
Page 22
LT3743 TYPICAL APPLICATIONS 6V to 36V, 2A LED Driver With Shunted Output EN/UVLO EN/UVLO V IN INTV PWM CC CTRL_SEL CTRL_SEL RT HG SYNC 82.5k CBOOT V SW LT3743 REF 2.2nF CTRL_L V CC_INT CONTROL R LG HOT CTRL_H INPUT ...
Page 23
TYPICAL APPLICATIONS EN/UVLO V 82.5k 2.2nF R CONTROL HOT 499Ω R NTC 10k 10nF Switched Cathode PWM Dimming (100: 20A PWM 5V/DIV I LED 10A/DIV SW 10V/DIV 10μs/DIV 6V to 30V, 20A LED Driver with Switched Cathode V ...
Page 24
LT3743 TYPICAL APPLICATIONS 24V, 20A 3-LED Driver V EN/UVLO EN/UVLO PWM PWM V CTRL_SEL CC_INT RT HG SYNC 82.5k CBOOT V LT3743 SW REF 2.2nF 20k V CC_INT CTRL_H LG 60.4k R HOT GND 499Ω CTRL_L SENSE SENSE PWMGH CTRL_T ...
Page 25
PACKAGE DESCRIPTION 4.50 0.05 3.10 0.05 2.50 REF 2.65 0.05 0.25 0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED PIN 1 TOP MARK (NOTE 6) 5.00 0.10 (2 SIDES) NOTE: ...
Page 26
LT3743 PACKAGE DESCRIPTION 4.75 (.187) 2.74 6.60 0.10 (.108) 4.50 0.10 SEE NOTE 4 RECOMMENDED SOLDER PAD LAYOUT 4.30 – 4.50* (.169 – .177) 0.09 – 0.20 0.50 – 0.75 (.0035 – .0079) (.020 – .030) NOTE: 1. CONTROLLING DIMENSION: ...
Page 27
... Corrected M2 and M3 part numbers on Typical Applications drawings Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...
Page 28
... Dimming = 400:1 True Color PWM, OUT(MAX) = 13.5V, Dimming = 3000:1 True Color PWM, OUT(MAX) = 36V, Dimming = 1000:1 True Color PWM, OUT(MAX) = 40V, Dimming = 1000:1 True Color PWM, OUT(MAX) LT 0810 REV B • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2009 3743 TA08b 3743fb ...