LT4351 MOSFET Diode-OR Controller FEATURES DESCRIPTION n Low Loss Replacement for ORing Diode in Multiple The LT®4351 creates a near ideal diode using external Sourced Power Supplies single or back-to-back N-channel MOSFETs. This ideal n External N-Channel MOSFETs for High Current diode function permits low loss ORing of multiple power Capability sources. Power sources can easily be ORed together to n Internal Boost Regulator Supply for MOSFET increase total system power and reliability with minimal Gate Drive effect on supply voltage or efficiency. Disparate power n Wide Input Range: 1.2V to 18V supplies can be efficiently ORed together. n Fast Switching MOSFET Gate Control The IC monitors the input supply with respect to the load n Input Under and Overvoltage Detection and turns on the MOSFET(s) when the input supply is n STATUS and FAULT Outputs for Monitoring higher. If the MOSFET’s R is sufficiently small, the n Internal MOSFET Gate Clamp DS(ON) LT4351 will regulate the voltage across the MOSFET(s) n Available in a 10-pin MSOP Package to 15mV. A STATUS pin indicates the MOSFET on-state. APPLICATIONS An internal boost regulator generates the MOSFET gate n Paralleled Power Supplies drive voltage. Low operating voltage allows for ORing of n Uninterrupted Supplies supplies as low as 1.2V. n High Availability Systems The LT4351 will disable power passage during undervolt- n N + 1 Redundant Power Supplies age or overvoltage conditions. These voltages are set by L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks resistive dividers on the UV and OV pins. The undervoltage and PowerPath and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. threshold has user programmable hysteresis. Overvoltage detection is filtered to reduce false triggering. The LT4351 is available in a 10-pin MSOP package. TYPICAL APPLICATION Dual 5V Redundant Supply Si4862DY Si4862DY POWER 5V 5V COMMON 5V POWER SUPPLY SUPPLY 1 10µF 10µF 2 1× 1× 4.7µH CLOAD LOAD 1µF 1µF 4.7µH VIN GATE OUT OUT GATE VIN MBR0530 MBR0530 VDD VDD MBR0530 LT4351 LT4351 MBR0530 SW STATUS STATUS SW 24.9k 24.9k 1% UV 1% UV FAULT FAULT 232Ω 232Ω 1% 1% OV GND GND OV 1.47k 1.47k 4351 TA01 1% 1% 4351fd 1 LT4351 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) VIN Voltage ................................................ –0.3V to 19V TOP VIEW OUT Voltage ............................................. –0.3V to 19V GATE 1 10 OUT VDD 2 9 STATUS V Voltage .............................................. –0.3V to 30V VIN 3 8 FAULT DD SW 4 7 UV FAULT, STATUS Voltages .......................... –0.3V to 30V GND 5 6 OV FAULT, STATUS Current .......................................... 8mA MS PACKAGE 10-LEAD PLASTIC MSOP UV, OV Voltages ......................................... –0.3V to 9V TJMAX = 125°C, θJA = 120°C/W SW Voltage .............................................. –0.3V to 32V Operating Temperature Range LT4351C .................................................. 0°C to 70°C LT4351I ............................................... –40°C to 85°C Junction Temperature (Note 2) ............................ 125°C Storage Temperature Range .................. –65°C to 150°C Lead Temperature (Soldering, 10 sec) .................. 300°C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LT4351CMS#PBF LT4351CMS#TRPBF LTZZ 10-Lead Plastic MSOP 0°C to 70°C LT4351IMS#PBF LT4351IMS#TRPBF LTA1 10-Lead Plastic MSOP –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = VOUT = 5V, VDD = 16.1V, VUV = 0.4V, VOV = 0.2V, GATE Open, unless otherwise specified. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Supply and Protection l VIN Operating Range 1.2 18 V l IVIN VIN Supply Current VIN = 1.2V, VOUT = 1.1V, VDD = 12.3V 1.41 2 mA l VIN = 18V, VOUT = 17.9V, VDD = 29.1V 1.71 2.1 mA l VUV(TH) Undervoltage Turn-Off Voltage UV Falling 290 300 310 mV Threshold l IUV(HYST) IUV Hysteresis Difference Between IUV at VUV(TH) + 10mV and 7 10 13 µA VUV(TH) – 10mV l IUV UV Input Bias Current VUV = VUV(TH) + 10mV –100 –400 nA l VOV(TH) Overvoltage Threshold OV Rising 290 300 310 mV 4351fd 2 LT4351 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = VOUT = 5V, VDD = 16.1V, VUV = 0.4V, VOV = 0.2V, GATE Open, unless otherwise specified. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS l IOV OV Input Bias Current VOV = VOV(TH) – 10mV –100 –400 V l VF(ON) FAULT Pin On-Voltage IF = 5mA in Fault Condition 0.14 0.25 V l IF(OFF) FAULT Pin Leakage Current VF = 30V, VIN = 4.9V 0.04 1 µA Boost Supply l VBR Boost Regulation Trip Voltage Measured as VDD to VIN, Rising Edge 10.2 10.7 11.4 V tOFF Boost Supply Off-Time 600 ns l ISWLIM Boost Supply Switch Current Limit 350 450 650 mA Gate Drive l VIOR Input-to-Output Regulated Voltage 4 15 25 mV l ∆VGL Gate Voltage Limit VIN = 5V, VOUT = 4.9V, VDD = 13V Measured with –2.3 –3 V Respect to VDD l ∆VG(MAX) Maximum Gate Voltage VIN = 5V, VOUT = 4.9V, VDD = 16.1V Measured with 7 7.4 7.8 V Respect to VOUT l VG(OFF) Gate Off-Voltage VOUT = 5.1V 0.16 0.30 V IGSO Gate Source Current VOUT = 4.9V, VGATE = 9V 0.670 A IGSK Gate Sink Current VOUT = 5.1V, VGATE = 9V 0.670 A l VDD Operating Range 30 V l IVDD VDD Supply Current VIN = 1.2V, VOUT = 1.1V, VDD = 12.3V, GATE Open 3 4 mA l VIN = 18V, VOUT = 17.9V, VDD = 29.1V, GATE Open 3.6 5.6 mA Status Functions l ∆VGIS Minimum Gate Voltage for Turning VOUT = 4.9V, ISTATUS = 1mA 0.75 1 V On Status VIOGF VIN to VOUT Fault Voltage with VOUT Falling, Measured with Respect to VIN 185 210 230 mV Open Gate l VST(ON) Status Pin On-Voltage IST = 5mA, VOUT = 4.9V, Status On 0.13 0.25 V l IST(OFF) Status Pin Leakage Current VST = 30V, Status Off, VIN = 4.9V 0.04 1 µA Note 1: Stresses beyond those listed under Absolute Maximum Ratings Note 2: TJ is calculated from the ambient temperature TA and power may cause permanent damage to the device. Exposure to any Absolute dissipation PD according to the following formula: Maximum Rating condition for extended periods may affect device TJ = TA + (PD • 120°C/W) reliability and lifetime. 4351fd 3 LT4351 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. Undervoltage Threshold Overvoltage Threshold vs Temperature vs Temperature Undervoltage Threshold vs VIN 310 305 310 VIN = 1.2V VIN = 1.2V 308 VIN = 5V VIN = 5V 308 VIN = 12V 303 VIN = 12V 306 306 VIN = 20V VIN = 20V 304 304 301 302 302 (mV) (mV) (mV) 300 299 300 UV(TH) OV(TH) 298 UV(TH) 298 V V V 297 296 296 294 294 295 292 292 290 293 290 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 0 2 4 6 8 10 12 1416 18 20 TEMPERATURE (°C) TEMPERATURE (°C) VIN (V) 4351 G01 4351 G02 4351 G03 Overvoltage Hysteresis Overvoltage Turn-Off Delay Overvoltage Threshold vs VIN vs Temperature vs Overvoltage Overdrive 310 25 20 VIN = 5V VIN = 5V 308 18 306 20 16 304 14 302 15 12 (mV) 300 10 UV(TH) 298 10 8 V 6 296 OV HYSTERESIS (mV) TURN-OFF DELAY (µs) 294 5 4 292 2 290 0 0 0 2 4 6 8 10 12 1416 18 20 –50 –25 0 25 50 75 100 125 0 5 10 15 20 25 30 35 VIN (V) TEMPERATURE (°C) OV VOLTAGE ABOVE THRESHOLD (mV) 4351 G04 4351 G05 3451 G06 IVIN vs Temperature IVDD vs Temperature Gate Off-Voltage vs Temperature 2.0 4.5 0.50 VIN = 1.2V VIN = 1.2V 1.9 VIN = 5V VIN = 5V 0.45 VIN = 12V VIN = 12V 1.8 4.0 0.40 VIN = 5V VIN = 20V VIN = 20V VOUT = 5V 1.7 0.35 1.6 3.5 0.30 (V) (mA) (mA) 1.5 0.25 GOFF VIN VDD I V 1.4 I 3.0 0.20 VIN = 5V VOUT = 5.1V 1.3 0.15 1.2 2.5 0.10 1.1 0.05 1.0 2.0 0 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 4351 G07 4351 G08 4351 G09 4351fd 4 LT4351 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. GATE Pin Turn On and Off Waveform with 10nF Capacitor Load Typical SW Pin Waveform TURN ON VGATE VSW 2V/DIV 5V/DIV TURN OFF 4351 G10 4351 G11 50ns/DIV 500ns/DIV VIN = 5V VIN = 5V VOUT = 4.9V TO 5.1V SQUARE WAVE L = 4.7µH SW Pin Waveform at Maximum Typical SW Pin Waveform Boost Regulator Output VSW VSW 5V/DIV 5V/DIV 4351 G12 4351 G13 10µs/DIV 10µs/DIV VIN = 5V VIN = 5V 4.7µH INDUCTOR 4.7µH INDUCTOR 4351fd 5 LT4351 PIN FUNCTIONS GATE (Pin 1): MOSFET Gate Drive Pin.