LT3756/LT3756-1/LT3756-2 - 100VIN, 100VOUT LED …

1 LT3756/LT3756-1/LT3756-2 375612fbTypical applicaTionFeaTuresapplicaTionsDescripTi on100 VIN, 100 VOUT LED ControllerThe LT 3756, LT3756-1 and LT3756-2 are DC/DC control-lers designed to operate as a constant-current source for driving high current LEDs. They drive a low side external N-channel power MOSFET from an internal regulated supply. The fixed frequency, current-mode architecture results in stable operation over a wide range of supply and output voltages. A ground referenced voltage FB pin serves as the input for several LED protection features, and also makes it possible for the converter to operate as a constant-voltage source. A frequency adjust pin allows the user to program the frequency from 100kHz to 1 MHz to optimize efficiency, performance or external component size. The LT3756/LT3756-1/LT3756-2 sense output current at the high side of the LED string. High side current sensing is the most flexible scheme for driving LEDs, allowing boost, buck mode or buck-boost mode configuration.

2 The PWM input provides LED dimming ratios of up to 3000:1, and the CTRL input provides additional analog dimming Efficient 30W White LED Headlamp Drivern 3000:1 True Color PWM Dimmingn Wide Input Voltage Range: 6V to 100Vn Output Voltage Up to 100Vn Constant-Current and Constant-Voltage Regulationn 100mV High Side Current Sensen Drives LEDs in Boost, Buck Mode, Buck-Boost Mode, SEPIC or Flyback Topologyn Adjustable Frequency: 100kHz to 1 MHzn Open LED Protectionn Programmable Undervoltage Lockout with Hysteresisn Improved Open LED Status Pin (LT3756-2)n Frequency Synchronization (LT3756-1)n PWM Disconnect Switch Drivern CTRL Pin Provides Analog Dimmingn Low Shutdown Current: <1 An Programmable Soft-Startn Thermally Enhanced 16-Lead QFN (3mm 3mm) and MSOP Packagesn High Power LED Applicationsn Current Limited Constant Voltage Applicationsn Battery ChargingVINLT3756-222 FVIN8V TO 60V(100V TRANSIENT) F30 WLEDSTRING375612 TA01aOPENLEDPWMSSRTISNGATESENSEPWMOUTE fficiency vs VINVIN (V)02080 EFFICIENCY (%)84889296100406080375612 TA01bL, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation.

3 True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by Patents, including 7199560 and 375612fbabsoluTe MaxiMuM raTingsVIN ..100 VSHDN/UVLO ..100 VISP, ISN ..100 VINTVCC .. VIN + , 8 VGATE, PWMOUT (Note 4) ..INTVCC + , PWM, OPENLED ..12 VVC, VREF , SS, FB ..3 VSYNC ..8V(Note 1)orDer inForMaTionLEAD FREE FINISHTAPE AND REELPART MARKING*PACKAGE DESCRIPTIONTEMPERATURE RANGELT3756 EMSE#PBFLT3756 EMSE#TRPBF375616-Lead Plastic MSOP 40 C to 125 CLT3756 IMSE#PBFLT3756 IMSE#TRPBF375616-Lead Plastic MSOP 40 C to 125 CLT3756 EMSE-1#PBFLT3756 EMSE-1#TRPBF3756116-Lead Plastic MSOP 40 C to 125 CLT3756 IMSE-1#PBFLT3756 IMSE-1#TRPBF3756116-Lead Plastic MSOP 40 C to 125 CLT3756 EMSE-2#PBFLT3756 EMSE-2#TRPBF3756216-Lead Plastic MSOP 40 C to 125 CLT3756 IMSE-2#PBFLT3756 IMSE-2#TRPBF3756216-Lead Plastic MSOP 40 C to 125 CLT3756 HMSE-2#PBFLT3756 HMSE-2#TRPBF3756216-Lead Plastic MSOP 40 C to 150 CLT3756 EUD#PBFLT3756 EUD#TRPBFLDMQ16-Lead (3mm 3mm) Plastic QFN 40 C to 125 CLT3756 IUD#PBFLT3756 IUD#TRPBFLDMQ16-Lead (3mm 3mm) Plastic QFN 40 C to 125 CLT3756 EUD-1#PBFLT3756 EUD-1#TRPBFLDMR16-Lead (3mm 3mm) Plastic QFN 40 C to 125 CLT3756 IUD-1#PBFLT3756 IUD-1#TRPBFLDMR16-Lead (3mm 3mm)

4 Plastic QFN 40 C to 125 CLT3756 EUD-2#PBFLT3756 EUD-2#TRPBFLFKB16-Lead (3mm 3mm) Plastic QFN 40 C to 125 CLT3756 IUD-2#PBFLT3756 IUD-2#TRPBFLFKB16-Lead (3mm 3mm) Plastic QFN 40 C to 125 CConsult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping more information on lead free part marking, go to: This product is only offered in trays. For more information go to: OR OPENLEDTOP VIEW17 GNDMSE PACKAGE16-LEAD PLASTIC MSOP TJMAX = 125 C (E-,I-GRADES), TJMAX = 150 C (H-GRADE), JA = 43 C/W, JC = 4 C/WEXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB161514135678 TOP VIEW17 GNDUD PACKAGE16-LEAD (3mm s 3mm) PLASTIC QFN91011124321 VREFPWMSYNC OR OPENLEDSSFBPWMOUTGATESENSECTRLVCISPISNRT SHDN/UVLOINTVCCVIN TJMAX = 125 C, JA = 68 C/W, JC = C/WEXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCBpin conFiguraTionRT .. Junction Temperature Range (Notes 2, 3) LT3756E, LT3756I.

5 40 C to 125 C LT3756H .. 40 C to 150 CStorage Temperature Range .. 65 C to 150 CLead Temperature (Soldering, 10 sec) MSE .. 300 CLT3756/LT3756-1/LT3756-2 375612fbelecTrical characTerisTics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25 C. VIN = 24V, SHDN/UVLO = 24V, CTRL = 2V, PWM = 5V, unless otherwise Minimum Operating VoltageVIN Tied to INTVCCl6 VVIN Shutdown IQSHDN/UVLO = 0V, PWM = 0V SHDN/UVLO = , PWM = 5 A AVIN Operating IQ (Not Switching)PWM = Voltage100 A IVREF 0 Line Regulation6V VIN Current Limit Thresholdl98108118mVSENSE Input Bias CurrentCurrent Out of Pin40 ASS Pull-Up CurrentCurrent Out of Pin81013 AError AmplifierISP/ISN Full-Scale Current Sense ThresholdFB = 0V, ISP = 48Vl96100103mVISP/ISN Current Sense Threshold at CTRL = 0 VCTRL = 0V, FB = 0V, ISP = 48V 12 7mVCTRL Pin Range for Current Sense Threshold Input Bias CurrentCurrent Out of Pin50100nALED Current Sense Amplifier Input Common Mode Range (VISN) Short-Circuit ThresholdISN = 0V115150200mVISP/ISN Short-Circuit Fault Sensing Common Mode Range (VISN)l03 VISP/ISN Input Bias Current (Combined)PWM = 5V (Active), ISP = ISN = 48V PWM = 0V (Standby)

6 , ISP = ISN = 48V55 0 A ALED Current Sense Amplifier gmV(ISP ISN) = 100mV120 SVC Output Impedance1V < VC < 2V15000k VC Standby Input Bias CurrentPWM = 0V 2020nAFB Regulation Voltage (VFB) ISP = ISNl VFB Amplifier gmFB = VFB, ISP = ISN480 SFB Pin Input Bias CurrentCurrent Out of Pin40100nAFB Open LED ThresholdOPENLED Falling (LT3756 and LT3756-2)VFB 65mVVFB 50mVVFB 40mVVFB Overvoltage ThresholdPWMOUT Falling VFB + 50mVVFB + 60mV VFB + 75mVVVC Current Mode Gain ( VVC/ VSENSE)4V/VOscillatorSwitching FrequencyRT = 100k RT = 10kl90 925100 1000125 1050kHz kHzMinimum Off-Time170nsLinear RegulatorINTVCC Regulation (VIN INTVCC)IINTVCC = 10mA, VIN = 7V1 VINTVCC Undervoltage Current Limit141723mAINTVCC Current in ShutdownSHDN/UVLO = 0V, INTVCC = 7V812 ALT3756/LT3756-1/LT3756-2 375612fbelecTrical characTerisTics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25 C.

7 VIN = 24V, SHDN/UVLO = 24V, CTRL = 2V, PWM = 5V, unless otherwise Inputs/OutputsPWM Input High Input Low Pin Resistance to GND4560k PWMOUT Output Low (VOL)050mVPWMOUT Output High (VOH)INTVCC Threshold Voltage Falling E-, I-Grades H Gradel VSHDN/UVLO Rising Hysteresis20mVSHDN/UVLO Input Low VoltageIVIN Drops Below 1 Pin Bias Current LowSHDN/UVLO = ASHDN/UVLO Pin Bias Current HighSHDN/UVLO = Output Low (VOL)IOPENLED = (LT3756 and LT3756-2)200mVSYNC Pin Resistance to GNDLT3756-1 Only30k SYNC Input HighLT3756-1 Input LowLT3756-1 Drivertr GATE Driver Output Rise TimeCL = 3300pF35nstf GATE Driver Output Fall TimeCL = 3300pF35nsGATE Output Low (VOL) Output High (VOH)INTVCC 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and 2: The LT3756E, LT3756E-1 and LT3756E-2 are guaranteed to meet performance specifications from 0 C to 125 C junction temperature.

8 Specifications over the 40 C to 125 C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LT3756I, LT3756I-1 and LT3756I-2 are guaranteed to meet performance specifications over the 40 C to 125 C operating junction temperature range. The LT3756H-2 is guaranteed to meet performance specifications over the full 40 C to 150 C operating junction temperature range. High junction temperatures degrade operating lifetimes. Operating lifetime is derated at junction temperatures greater than 125 3: The LT3756 includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed the maximum operating junction temperature when overtemperature protection is active. Continuous operating above the specified maximum operating junction temperature may impair device 4: GATE and PWMOUT pins are driven either to GND or INTVCC by internal switches.

9 Do not connect these pins externally to a power 375612fbTypical per ForMance characTerisTicsFB Regulation Voltage vs Temperature VREF Voltage vs Temperature VREF Voltage vs VIN Switching Frequency vs RTSwitching Frequency vs TemperatureSHDN/UVLO Hysteresis Current vs Temperature V(ISP ISN) Threshold vs VCTRL V(ISP ISN) Threshold vs VISPV(ISP ISN) Threshold vs TemperatureTA = 25 C, unless otherwise (k)SWITCHING FREQUENCY (kHz)375612 G071000010001001010100 VCTRL (V)0 20V(ISP ISN) THRESHOLD (mV) G01 ISP VOLTAGE (V)097V(ISP ISN) THRESHOLD (mV)991012040806010398100102100375612 G02 VCTRL = 2V979910110398100102375612 G03V(ISP ISN) THRESHOLD (mV)TEMPERATURE ( C) 5005075 2525100150125 VCTRL = 2V375612 G04 VFB (V)TEMPERATURE ( C) 5005075 G05 VREF (V)TEMPERATURE ( C) 5005075 (V) (V) G06375612 G08 SWITCHING FREQUENCY (kHz)TEMPERATURE ( C) 5005075 2525100150125300350400450500RT = G09 TEMPERATURE ( C) 5005075 ( A) 375612fbTypical per ForMance characTerisTics INTVCC Voltage vs VININTVCC Current Limit vs Temperature INTVCC Voltage vs Temperature Quiescent Current vs VINSENSE Current Limit Threshold vs TemperatureSHDN/UVLO Threshold vs TemperatureTA = 25 C, unless otherwise G11 SENSE THRESHOLD (mV)TEMPERATURE ( C)9010011095105 5005075 2525100150125375612 G12 SHDN/UVLO VOLTAGE (V)TEMPERATURE ( C) RISINGSHDN/UVLO FALLING 5005075 2525100150125 Gate Rise/Fall Time vs CapacitanceSENSE Current Limit Threshold vs Duty Cycle V(ISP-ISN) Threshold vs FB VoltageVIN (V)0 VIN CURRENT (mA) G10020408060100 PWM = 0 VVIN (V)VINTVCC (V)375612 G1304826020408060100375612 G14 INTVCC CURRENT LIMIT (mA)TEMPERATURE ( C)101420121618 5005075 2525100150125375612 G15 INTVCC (V)TEMPERATURE ( C) 5005075 CYCLE (%)90 SENSE THRESHOLD (mV)10011095105375612 G160255075100FB VOLTAGE (V)375612 (ISP ISN) THRESHOLD (mV)VCTRL = 2 VCAPACITANCE (nF)

10 375612 G180246108040100206080 TIME (ns)GATE RISETIMEGATEFALL TIME10% TO 90% LT3756/LT3756-1/LT3756-2 375612fbpin FuncTionsPWMOUT (Pin 1/Pin 11): Buffered Version of PWM Signal for Driving LED Load Disconnect NMOS or Level Shift. This pin also serves in a protection function for the FB overvoltage condition will toggle if the FB input is greater than the FB regulation voltage (VFB) plus 60mV (typical). The PWMOUT pin is driven from INTVCC. Use of a FET with gate cut-off voltage higher than 1V is (Pin 2/Pin 12): Voltage Loop Feedback Pin. FB is intended for constant-voltage regulation or for LED protec-tion/open LED detection. The internal transconductance amplifier with output VC will regulate FB to (nominal) through the DC/DC converter. If the FB input is regulating the loop, the OPENLED pull-down is asserted. This ac-tion may signal an open LED fault. If FB is driven above the FB threshold (by an external power supply spike, for example), the OPENLED pull-down will be de-asserted and the PWMOUT pin will be driven low to protect the LEDs from an overcurrent event.