lt3743 Linear Technology Corporation, lt3743 Datasheet
lt3743
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lt3743 Summary of contents
Page 1
... CTRL_L, CTRL_H and CTRL_T pins and with PWM dimming on the PWM and CTRL_SEL pins. Through the use of externally switched load capacitors, the LT3743 is capable of changing regulated LED current levels within several μs, providing accurate, high speed PWM dimming between two current levels. The switching frequency is programmable from 200kHz to 1MHz through an external resistor on the RT pin ...
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... 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. Consult LTC Marketing for information on non-standard lead based fi nish parts. For more information on lead free part marking, go to: For more information on tape and reel specifi ...
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... EN/UVLO = 1.45V IN With a 67kΩ Resistor from V to GND REF 1.5V CTRL_H CTRL_L With OUT (Note 4) (Note 4) (Note 4) V – CBOOT CC_INT R = 40kΩ 200kΩ T LT3743 MIN TYP MAX UNITS 6 36 1.8 2 0.1 1 1.49 1.55 1.61 130 mV 5.5 1.0 1.0 1.0 0 1.5 100 l 1.96 2 2.04 l ...
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... Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT3743 will function with a supply voltage as low as 4.5V, but to keep the gate drive voltages above 4V, the V V for operation below 6.0V ...
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... IN 1. 1.98 1.97 –50 – TEMPERATURE (°C) RT Pin Current Limit 125 –50 – TEMPERATURE (°C) LT3743 I in Shutdown Q 0.5 0.4 0.3 130°C 0.2 0.1 25°C 130°C 25°C –50° (V) IN 3743 G02 V Current Limit REF 1.6 1 25° ...
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... 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) LOAD 3743 G13 Open-LED Timeout –50 – TEMPERATURE (°C) 3743 G16 6 CBOOT-SW UVLO Voltage 3.00 2.75 2.50 2.25 2.00 1.75 1.50 –50 –15 ...
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... TEMPERATURE (°C) Regulation Accuracy CTRL_H = 1.5V 12V –1 –2 –3 125 0 2.5 5.0 7.5 OUTPUT VOLTAGE (V) LT3743 LG Driver R DS(ON PMOS 2 NMOS 1 0 125 –50 – TEMPERATURE (°C) 3743 G20 Minimum On-Time 150 120 125 – ...
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... 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 with 10A Regulated Inductor Current V OUT 2V/DIV I L 5A/DIV 3743 G34 100μ ...
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... PWMGH (Pin 19/Pin 21): The PWMGH output pin drives . The S the gate of an external FET to connect one of the switch- – referenced to ing regulator output capacitors to the load. The output impedance is approximately 2.5Ω. LT3743 – is the noninverting input . S resistor should be chosen to T 3743f ...
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... 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 switch- ing regulator output capacitors to the load. The output impedance is approximately 2.5Ω. HG (Pin 23/Pin 24 the top FET gate drive signal that controls the state of the high side external power FET. The driver impedance is 2.5Ω ...
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... MIRROR 5.5μ 40μA OUT – 90k + VOLTAGE REGULATOR AMP + – OPEN-LED COMPARATOR 2.5Ω 2.5Ω Figure 1. Block Diagram LT3743 40μF V CC_INT 27 AND HIGH SIDE CBOOT DRIVER 25 HG 0.1μ 2.2μH LOW SIDE DRIVER + ...
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... CTRL_SEL pins are both high, the regulated current in the inductor is determined by the analog voltage at the CTRL_H pin. The LT3743 uses a unique switched output capacitor topology and two independent compensation networks to transition between the two regulated current states in less than 2μs. When the CTRL_SEL pin is low and the PWM pin is high, the PWMGL output pin is high, switch- ing in the output capacitor for the CTRL_L current level ...
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... S frequency. Using this equation, the inductor will have ap- proximately 15% ripple at maximum regulated current. POWER DISSIPATION (W) Table 2. Recommended Inductor Manufacturers 0.05 0.25 0.5 1.25 Würth Electronics 3743 F02 LT3743 – pins. The saturation current for the inductor ( ) ( ) ⎞ 2 • V – ⎟ ⎟ . • • • ...
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... Another power loss related to switching MOSFET selection is the power lost to driving the gates. The total gate charge must be charged and discharged each switching cycle. G The power is lost to the internal LDO within the LT3743. The power lost to the charging of the gates is Power loss to the GS ...
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... POSCAP capacitors that have a voltage rating that is at least 50% higher than the regulated voltage C Capacitor Selection BOOT The C BOOT more than 50nF to ensure proper operation of the LT3743. Use 220nF for high current switching MOSFETs with high gate charge. LT3743 2.5 2.0 1.5 TOTAL 1 ...
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... LED Current Dimming The LT3743 provides the capability of traditional zero to full current PWM dimming as well as PWM dimming between two regulated LED current states. When the PWM signal is low, no switching occurs and the output capacitors are disconnected from ground ...
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... When measuring the LED current do not use a current probe. The core material used in most probes adds inductance and slows the rise time of the LED current. Instead, when measuring the current, use a sense resistor. LT3743 . CTRL_L ...
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... 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 current LEDs. The regulated output voltage is programmed using a resistor divider from the output and ground (Figure 12) ...
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... R2 greater than 375k. LED Current Derating Using the CTRL_T Pin The LT3743 is designed specifi cally for driving high cur- rent LEDs. Most high current LEDs require derating the maximum current based on operating temperature to prevent damage to the LED ...
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... Since the closed-loop gain at the switching frequency produces the error signal slope, the output impedance of V • 11μA/V CTRL L MODULATOR + g m ERROR AMP – Figure 16. LT3743 Average Current Mode Control Scheme Table 6. Recommended Compensation Values V ( ...
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... M2: RJK0346DPA M3, M4: Si7236DP Effi ciency (Stepping from 2A to 20A 12V IN GREEN LED CTRL_SEL DIMMING DUTY CYCLE (%) 3743 TA02b LT3743 V IN 12V V OUT 20A MAXIMUM 1μF D1 1mF 1mF M3 M4 40.2k 1mF 10k 3743 TA02 100 3743f 21 ...
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... VCH 34k 34k 4.7nF 4.7nF 6V to 36V, 2A LED Driver With Current Limited Shunted Output V EN/UVLO EN/UVLO IN INTV PWM CC CTRL_SEL CTRL_SEL RT HG SYNC 82.5k CBOOT V SW LT3743 REF 2nF CONTROL CTRL_H INPUT V CC_INT R LG HOT CTRL_L 45.3k GND + CTRL_T SENSE – SENSE R NTC PWMGH ...
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... CTRL_H GND + CTRL_T SENSE – SENSE PWMGL SS PWMGH FB VCL VCH D1: LUMINUS PT121 L1: MVR1261C-112ML 34k M1: RJK0365DPA M2: RJK0328DPB 4.7nF M3: SiR496DP 3743 TA05b LT3743 30V 80μF V OUT 20A MAXIMUM 2.5mΩ 1mF D1 M3 60.4k 10k 3743 TA05 0A to 20A Effi ciency 100 ...
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... LT3743 TYPICAL APPLICATIONS μCONTROLLER 82.5k R HOT 45.3k R NTC 680k 10nF 24 12V, 5A Lithium-Ion Battery Charger EN/UVLO V IN PWM 1μF CTRL_SEL CTRL_H HG CTRL_L 100nF RT CBOOT 3.6μH SYNC LT3743 REF CC_INT 20μF 2nF LG GND + CTRL_T SENSE – SENSE PWMGH SS PWMGL FB VCL VCH 56.2k 56.2k 9nF 9nF V IN 12V 20μ ...
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... PWMGL SS FB VCL VCH 24.3k 4.7nF Effi ciency 100 24V IN 3 RED LEDs DUTY CYCLE (%) 3743 TA07b LT3743 V IN 24V 80μF V OUT 2.5mΩ 20A MAXIMUM 500μF RED LEDs 316k 20k 3743 TA07 100 3743f 25 ...
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... LT3743 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: 1. DRAWING PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220 VARIATION (WXXX-X). 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4 ...
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... BSC 0.195 – 0.30 (.0077 – .0118) 4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE LT3743 9.60 – 9.80* (.378 – .386) 4.75 (.187 ...
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... LT3743 TYPICAL APPLICATION 24V, 40A Pulsed LED Driver V EN/UVLO EN/UVLO IN PWM PWM CTRL_SEL CTRL_SEL RT HG SYNC 150k CBOOT V LT3743 SW REF 1μF CTRL_L 40k V CC_INT 1μ HOT 45.2k CTRL_H 40k GND 1μF + SENSE CTRL_T – SENSE R NTC PWMGH 680k SS PWMGL 1μF FB VCL ...