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LT3641 Dataheets PDF



Part Number LT3641
Manufacturers Linear
Logo Linear
Description Dual Monolithic Buck Regulator
Datasheet LT3641 DatasheetLT3641 Datasheet (PDF)

LT3641 Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer FEATURES DESCRIPTION n High Voltage Buck Regulator: 4V to 42V Operating Range 1.3A Output Current n Input Transient Protection to 55V n Low Voltage Synchronous Buck Regulator: 2.5V to 5.5V Input Voltage Range 1.1A Output Current n Synchronizable, Adjustable 350kHz to 2.5MHz Switching Frequency n Programmable Power-On Reset Timer n Programmable Window Mode Watchdog Timer n Typical Quiescent Current: 290μA n Short-Cir.

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LT3641 Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer FEATURES DESCRIPTION n High Voltage Buck Regulator: 4V to 42V Operating Range 1.3A Output Current n Input Transient Protection to 55V n Low Voltage Synchronous Buck Regulator: 2.5V to 5.5V Input Voltage Range 1.1A Output Current n Synchronizable, Adjustable 350kHz to 2.5MHz Switching Frequency n Programmable Power-On Reset Timer n Programmable Window Mode Watchdog Timer n Typical Quiescent Current: 290μA n Short-Circuit Robust n Programmable Soft-Start n Low Shutdown Current: IQ < 1μA n Thermal Shutdown n Available in Thermally Enhanced 28-Lead (4mm × 5mm) QFN and 28-Lead TSSOP Packages APPLICATIONS n Industrial Power Supplies n Automotive Electronic Control Units L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. The LT®3641 is a dual channel, current mode monolithic buck switching regulator with a power-on reset and a watchdog timer. Both regulators are synchronized to a single oscillator with an adjustable frequency (350kHz to 2.5MHz). At light loads, both regulators operate in low ripple Burst Mode® to maintain high efficiency and low output ripple. The high voltage channel is a nonsynchronous buck with an internal 2.4A top switch that operates from an input of 4V to 42V and input transient protection to 55V. The low voltage channel operates from an input of 2.5V to 5.5V. Internal synchronous power switches provide high efficiency without the need of external Schottky diode. Both channels have cycle-by-cycle current limit, providing protection against shorted outputs. The power-on reset and watchdog timeout periods are both adjustable using external capacitors. The window mode watchdog timer flags when the μP pulses group too close together or too far apart. The LT3641 is available in a 28-pin 4mm × 5mm QFN package and 28-pin TSSOP package. Both packages have an exposed pad for low thermal resistance. TYPICAL APPLICATION 2MHz 5V/0.8A and 3.3V/0.5A Step Down Regulators VIN 7V TO 42V* VOUT1 100k μP 0.22μF 10μF EN/UVLO VIN SW SYNC WDE PGOOD2 BST SW1 DA FB1 100k RST1 RST2 WDO WDI LT3641 VIN2 EN2 SW2 1.5nF CWDT FB2 CPOR RT GND SS2 SS1 1.5nF 32.4k 1nF 1nF 4.7μH 301k 100k 2.2μH 226k 49.9k 3641 TA01a VOUT1 5V/0.8A 22μF VOUT2 3.3V/0.5A 22μF * FOR INPUT VOLTAGES ABOVE 42V RESTRICTIONS APPLY EFFICIENCY (%) EFFICIENCY (%) HV Channel Efficiency, 2MHz, VOUT1 = 5V 90 VIN = 12V 85 80 75 70 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 VOUT1 CURRENT (A) 3641 TA01b LV Channel Efficiency, 2MHz, VOUT2 = 3.3V 95 90 VIN2 = 5V 85 80 75 70 0 0.2 0.4 0.6 0.8 1.0 1.2 VOUT2 CURRENT (A) 3641 TA01c 3641fa 1 LT3641 ABSOLUTE MAXIMUM RATINGS (Note 1) VIN, EN/UVLO Voltage (Note 7) .................................55V WDE Voltage .............................................................30V BST Above SW, SW1 Voltage ....................... –0.3V to 6V SW1 Above SW Voltage............................... –0.3V to 6V VIN2, SYNC, EN2, PGOOD2, WDI, WDO, RST1, RST2, Voltages ....................... –0.3V to 6V SS1, SS2, FB1, FB2, RT, CWDT, CPOR Voltages……….............................. –0.3V to 2.5V SW2 Voltage ................................ –0.3V to (VIN2 + 0.3V) Operating Junction Temperature Range (Note 2) LT3641E ................................................. –40°C to 125°C LT3641I.................................................. –40°C to 125°C LT3641H................................................. –40°C to 150°C Storage Temperature Range................... –65°C to 150°C Lead Temperature, FE Only (Soldering, 10 sec) .... 300°C PIN CONFIGURATION TOP VIEW FB2 1 PGOOD2 2 28 SS2 27 EN2 EN/UVLO 3 26 GND SYNC 4 25 SW2 SS1 5 FB1 6 24 VIN2 23 GND RT 7 29 22 VIN RST2 8 GND 21 BST RST1 9 20 SW WDO 10 19 SW1 CWDT 11 18 DA CPOR 12 WDE 13 17 NC 16 GND WDI 14 15 GND FE PACKAGE 28-LEAD PLASTIC TSSOP θJA = 30°C/W, θJC = 8°C/W EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB TOP VIEW EN/UVLO PGOOD2 FB2 SS2 EN2 GND 28 27 26 25 24 23 SYNC 1 22 SW2 SS1 2 21 VIN2 FB1 3 20 GND RT 4 RST2 5 RST1 6 WDO 7 29 19 VIN GND 18 BST 17 SW 16 SW1 CWDT 8 15 DA 9 10 11 12 13 14 CPOR WDE WDI GND GND NC UFD PACKAGE 28-LEAD (4mm × 5mm) PLASTIC QFN θJA = 43°C/W, θJC = 3.4°C/W EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3641EFE#PBF LT3641EFE#TRPBF LT3641FE 28-Lead Plastic TSSOP –40°C to 125°C LT3641IFE#PBF LT3641IFE#TRPBF LT3641FE 28-Lead Plastic TSSOP –40°C to 125°C LT3641HFE#PBF LT3641HFE#TRPBF LT3641FE 28-Lead Plastic TSSOP –40°C to 150°C LT3641EUFD#PBF LT3641EUFD#TRPBF 3641 28-Lead (4mm × 5mm) Plastic QFN –40°C to 125°C LT3641IUFD#PBF LT3641IUFD#TRPBF 3641 28-Lead (4mm × 5mm) Plastic QFN –40°C to 125°C Consult LTC Mar.


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