LT3751 LINER [Linear Technology], LT3751 Datasheet
LT3751
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LT3751 Summary of contents
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... The FAULT pin indicates when the LT3751 has shut down due to either V voltage exceeding the user-programmed supply tolerances. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and ThinSOT is a trademark of Linear Technology Corporation ...
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... LT3751IFE LT3751IFE#TR LT3751EUFD LT3751EUFD#TR LT3751IUFD LT3751IUFD#TR Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: For more information on tape and reel specifications, go to: ...
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... Current Sourced from FB Pin, Measured at FB Pin Voltage (Note 6) (Note 7) 100kΩ 100kΩ DONE = 5V 100kΩ 100kΩ FAULT = 5V UVLO1 Pin Voltage = 1.24V UVLO2 Pin Voltage = 1.24V OVLO1 Pin Voltage = 1.24V OVLO2 Pin Voltage = 1.24V LT3751 MIN TYP MAX ...
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... Specifications over the –40°C to 125°C operating junction temperature range are assured by design characterization and correlation with statistical process controls. The LT3751I is guaranteed over the full –40°C to 125°C operating junction temperature range. Note 3: A 60V internal clamp is connected to RV UVLO1, UVLO2, OVLO1 and OVLO2 ...
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... UVLO1 Trip Voltage 1.236 1.234 1.232 1.230 1.228 V 1.226 1.224 –40 – 100 TEMPERATURE (°C) LT3751 CHARGE Pin Current 450 400 350 300 250 200 150 100 –40°C 50 25°C 125° PIN VOLTAGE (V) ...
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... LT3751 Typical perForMance characTerisTics Current Comparator Trip Voltage (Charge Mode) 109 – CSP CSN 108.5 108.0 107 12V 24V CC 107.0 –40 – 100 120 TEMPERATURE (°C) 3751 G10 FB Pin Bias Current 100 MEASURED AT FB PIN VOLTAGE ...
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... FAULT (Pin 6/Pin 4): Open Collector Indication Pin. When either V TRANS range internal UVLO condition occurs, a transistor turns on. The part will stop switching. This pin needs a proper pull-up resistor or current source. LT3751 DCM Trip Voltage (V DRAIN RV = RDCM = 25kΩ TRANS 0.64 ...
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... Turn-on ramp rates should be between 10ns to 10ms. CHARGE pin should not be directly ramped with V LT3751 may not properly initialize. CLAMP (Pin 9/Pin 7): Internal Clamp Voltage Selection Pin. Tie this pin activate the internal 5.6V gate CC driver clamp ...
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... ONE-SHOT CLOCK TIMING AND PEAK CURRENT CONTROL TO CHARGE ONE-SHOT 26kHz ONE-SHOT CLOCK DIE TO V 160ºC OUT MODE TEMP COMPARATOR CONTROL GND RBG R BG 1.33k LT3751 T1 D1 1:10 • RV TRANS 10µF 40.2k • RV TRANS 60V RV OUT RV OUT 40.2k DIFF . AMP COMPARATOR 60V WITH R ...
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... MODE 0.0V 3751 F01 Figure 1. FB Pin Modes CHARGE MODE When the FB pin voltage is below 1.16V, the LT3751 acts as a rapid capacitor charger. The charging operation has four basic states for charge mode steady-state operation (see Figure 2). 1. Start-Up The first switching cycle is initiated approximately 2µs after the CHARGE pin is raised high ...
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... Steps 2-4 continue until the target output voltage is reached. Start-Up Protection – The LT3751 at start-up, when the output voltage is very TRANS DS(ON) low (or shorted), usually does not have enough V node voltage to trip the DCM comparator. The part in start- up mode uses the internal 26kHz clock and an auxiliary current comparator ...
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... LOW NOISE REGULATION Low noise voltage regulation can be achieved by adding a resistive divider from the output node to the LT3751 FB pin. At start-up (FB pin below 1.16V), the LT3751 enters the charge mode to rapidly charge the output capacitor. Once the FB pin is within the threshold range of 1.16V to 1 ...
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... PRI t Figure 5. Modes of Operation (Steady State) ) NO-LOAD OPERATION 0 LIGHT LOAD MODERATE HEAVY LOAD LOAD Figure 6. Regulation Technique LT3751 LIGHT LOAD OPERATION DUTY CYCLE DUTY CYCLE CONTROL CONTROL FORCED BLANKING t ≈ 38µs PER NO-LOAD OPERATION LOAD CURRENT CHARGE MODE 3751 F06 ...
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... Figure 5 shows the use of duty-cycle control. No-Load Operation The LT3751 can remain in low noise regulation at very low loading conditions. Below a certain load current threshold (Light Load Operation), the output voltage would continue to increase and a runaway condition could occur. This is due to the periodic one-shot forced by the periodic refresh circuitry ...
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... Selecting Operating Mode Tie the FB pin to GND to operate the LT3751 as a capacitor charger. In this mode, the LT3751 charges the output at peak primary current in boundary mode operation. This constitutes maximum power delivery and yields the fast- est charge times ...
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... I • PK Efficiency V TRANS Note that the LT3751 regulation scheme varies the peak current based on the output load current. The maximum I is only reached during charge mode or during heavy PK load conditions where output power is maximized. 16 Transformer Design The transformer’s primary inductance the desired V parameters ...
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... V ΔV (V DRAIN The RV TRANS source. Pin current increases as the pin voltage is taken higher than the internal 60V Zener clamp. The LT3751 can operate from V 100 clamps by limiting the RV 3751 F09 Operating V tor dividers. Two applications are presented that operate ...
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... LT3751 applicaTions inForMaTion with V between 100V and 400V (refer to Typical TRANS Applications section). Consult applications engineering for applications with V operating above 400V. TRANS RV is required for capacitor charger applications but OUT may be removed for regulator applications. Note that the V comparator can be used as secondary protection OUT for regulator applications ...
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... FETs. The typical gate driver overshoot voltage is 0.5V above the clamp voltage. The LT3751’s gate driver also incorporates a PMOS pull- up device via the LVGATE pin. The PMOS pull-up driver should only be used for V applications below. ...
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... OS SENSE Disable the overvoltage lockouts by directly connecting the OVLO1 and OVLO2 pins to ground. The LT3751 provides internal Zener clamping diodes to protect itself in shutdown when V 55V. Supply voltages should only be applied to UVLO1, UVLO2, OVLO1 and OVLO2 with series resistance such that the Absolute Maximum pin currents are not exceeded. ...
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... I PRI Figure 11. Effects of RC Snubber LOW NOISE REGULATION The LT3751 has the option to provide a low noise regu- lated output voltage when using a resistive voltage divider from the output node to the FB pin. Refer to the Selecting Component Parameters section to design the transformer, NMOS power switch, output diode, and sense resistor. ...
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... DCM underneath the R Parasitic capacitance can cause unwanted behavior on these pins. 5. Thermal vias should be added underneath the Exposed Pad, Pin 21, to enhance the LT3751’s thermal perfor- mance. These vias should go directly to a large area of 150 200 ground plane. 3751 F14 6 ...
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... SECONDARY PRIMARY LT3751 3751fc 23 ...
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... LT3751 applicaTions inForMaTion 24 SECONDARY PRIMARY 3751fc ...
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... TRANS V = 100V, OUT V = 12V TRANS 400 0 200 400 600 800 1000 OUTPUT CAPACITANCE (µF) LT3751 V * M1, M2 REQUIRES PROPER OUT 500V HEATSINK/THERMAL DISSIPATION TO MEET MANUFACTURER’S SPECIFICATIONS + C4 ** THERMAL DISSIPATION OF T1 WILL LIMIT 1200µF THE CHARGE/DISCHARGE DUTY CYCLE OF C4 *** D2 MAY BE OMITTED FOR OUTPUT ...
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... LT3751 Typical applicaTions DANGER HIGH VOLTAGE! OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY V TRANS + 5V TO 24V C3 R6 680µF 40.2k RV TRANS OFF ON CHARGE RDCM CLAMP LT3751 24V C1 DONE TO 10µF HVGATE MICRO FAULT LVGATE R1, 69.8k UVLO1 V TRANS R2, 475k OVLO1 R3, 69.8k UVLO2 V CC ...
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... 550 70 400 65 50 150 250 350 OUTPUT VOLTAGE (V) LT3751 V OUT * T1 REQUIRES PROPER THERMAL MANAGEMENT 50V TO 500V TO ACHIEVE DESIRED OUTPUT POWER LEVELS REQUIRES PROPER HEAT SINK/THERMAL 220µF DISSIPATION TO MEET MANUFACTURER’S SPECIFICATIONS FOR ANY OUTPUT VOLTAGE BETWEEN 50V TO 500V, SET R12 GIVEN BY: ...
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... LT3751 Typical applicaTions DANGER HIGH VOLTAGE! OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY V F1, 1A TRANS 100V TO + 400VDC C3 R6, 625k 47µF R7, 97.6k RV TRANS OFF ON CHARGE RDCM CLAMP V LT3751 CC 10V 24V C1 DONE 10µF TO HVGATE MICRO FAULT LVGATE R1, 1.5M CSP UVLO1 V TRANS R2, 9M OVLO1 ...
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... R7 CC GND RBG 475 3751 TA06a R8 2.49k Efficiency 100 63W OUTPUT 48W OUTPUT 25W OUTPUT 100 120 140 160 180 250 INPUT VOLTAGE (V) LT3751 T1 • Npb D5 • 0.1µF 400µF • D4 Nsb R15 U2 • COMP C8 IN 0.01µ ...
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... VOUT2 VOUT3 3751 TA07b **SOURCE/SINK IDENTICAL CURRENTS FROM BOTH 1000µF 25.5k 10µF ×2 RV TRANS OFF ON CHARGE R6 CLAMP 11.5k V RDCM LT3751 10µF R1, 100k 25.5k DONE RV OUT R2, 100k FAULT R3, 66.5k HVGATE UVLO1 LVGATE V CC CSP R4, 464k OVLO1 25m CSN UVLO2 OVLO2 FB GND RBG R8 2 ...
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... BSC 0.195 – 0.30 (.0077 – .0118) 4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT MILLIMETERS (INCHES) *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE LT3751 6.40 – 6.60* (.252 – .260) 3.86 (.152 6.40 2.74 (.252) ( ...
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... LT3751 package DescripTion Please refer to http://www.linear.com/designtools/packaging/ 2.65 ± 0.05 4.50 ± 0.05 1.50 REF 3.10 ± 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). ...
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... Updated FE package drawing 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. LT3751 PAGE NUMBER 7 8 ...
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... RDCM CLAMP RV OUT DONE HVGATE V LVGATE CC FAULT CSP R5 UVLO1 6mΩ LT3751 CSN OVLO1 UVLO2 FB R9 OVLO2 1.13k GND RBG 3751 TA08 M1: FAIRCHILD FQP34N20L R1 THROUGH R4: USE 1% 0805 RESISTORS R5: IRC LR SERIES 2512 RESISTOR T1: SUMIDA PS07-299, 20A TRANSFORMER COMMENTS V : 2.75V to 5.5V, Charges Two Supercapacitors in Series to 4.8V or 5.3V IN Charges 220µ ...