LTC3418EUHF#PBF

LTC3418 8A, 4MHz, Monolithic Synchronous Step-Down Regulator Description Features n n n n n n n n n n n n n n High Efficiency: Up to 95% 8A Output Current 2.25V to 5.5V Input Voltage Range Low RDS(ON) Internal Switch: 35mΩ Tracking Input to Provide Easy Supply Sequencing Programmable Frequency: 300kHz to 4MHz 0.8V ±1% Reference Allows Low Output Voltage Quiescent Current: 380µA Selectable Forced Continuous/Burst Mode® Operation with Adjustable Burst Clamp Synchronizable Switching Frequency Low Dropout Operation: 100% Duty Cycle Power Good Output Voltage Monitor Overtemperature Protected 38-Lead Low Profile (0.75mm) Thermally Enhanced QFN (5mm × 7mm) Package Applications n n n n n Microprocessor, DSP and Memory Supplies Distributed 2.5V, 3.3V and 5V Power Systems Automotive Applications Point of Load Regulation Notebook Computers The LTC®3418 is a high efficiency, monolithic synchronous step-down DC/DC converter utilizing a constant frequency, current mode architecture. It operates from an input voltage range of 2.25V to 5.5V and provides a regulated output voltage from 0.8V to 5V while delivering up to 8A of output current. The internal synchronous power switch increases efficiency and eliminates the need for an external Schottky diode. Switching frequency is set by an external resistor or can be synchronized to an external clock. OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of loads and output capacitors. The LTC3418 can be configured for either Burst Mode operation or forced continuous operation. Forced continuous operation reduces noise and RF interference while Burst Mode operation provides high efficiency by reducing gate charge losses at light loads. In Burst Mode operation, external control of the burst clamp level allows the output voltage ripple to be adjusted according to the requirements of the application. A tracking input in the LTC3418 allows for proper sequencing with respect to another power supply. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131, 6724174. Typical Application 2.5V/8A Step-Down Regulator Efficiency and Power Loss vs Load Current 100 CIN 47µF ×4 SVIN TRACK PVIN 2.2M 30.1k 1000pF 0.2µH SW COUT 100µF ×2 LTC3418 PGOOD PGND RUN/SS SGND ITH 4.99k 820pF SYNC/MODE VFB 332Ω EFFICIENCY 10000 80 70 60 1000 POWER LOSS 100 50 40 4.32k 3418 TA01a 1.69k VOUT 2.5V 8A 100000 10 30 20 0.01 VIN = 3.3V VOUT = 2.5V 0.1 1 LOAD CURRENT (A) 10 3418 TA01b For more information www.linear.com/LTC3418 POWER LOSS (mW) RT 90 EFFICIENCY (%) VIN 2.8V TO 5.5V 1 3418fc 1 LTC3418 Absolute Maximum Ratings Pin Configuration (Note 1) PGND PGND PGND TRACK PGND PGND TOP VIEW PGND Input Supply Voltage.................................... –0.3V to 6V ITH, RUN/SS, VFB Voltages.......................... –0.3V to VIN SYNC/MODE Voltages................................. –0.3V to VIN TRACK Voltage........................................... –0.3V to VIN SW Voltage................................... –0.3V to (VIN + 0.3V) Operating Temperature Range (Note 2)................................................–40°C to 85°C Junction Temperature (Note 5).............................. 125°C Storage Temperature Range.................. –65°C to 125°C 38 37 36 35 34 33 32 SW 1 31 SW SW 2 30 SW PVIN 3 29 PVIN PVIN 4 28 PVIN PGOOD 5 27 SYNC/MODE RT 6 26 ITH 39 RUN/SS 7 25 VFB SGND 8 24 SVIN PVIN 9 23 PVIN PVIN 10 22 PVIN SW 11 21 SW 20 SW SW 12 PGND PGND PGND VREF PGND PGND PGND 13 14 15 16 17 18 19 UHF PACKAGE 38-LEAD (7mm × 5mm) PLASTIC QFN TJMAX = 125°C, θJA = 34°C/W, θJC = 1°C/W EXPOSED PAD (PIN 39) IS PGND, MUST BE SOLDERED TO PCB order information http://www.linear.com/product/LTC3418#orderinfo LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3418EUHF#PBF LTC3418EUHF#TRPBF 3418 38-Lead (7mm × 5mm) Plastic QFN –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. 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/. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix. 2 3418fc For more information www.linear.com/LTC3418 LTC3418 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 3.3V. (Note 2) SYMBOL PARAMETER VIN Input Voltage Range VFB Regulated Feedback Voltage CONDITIONS MIN TYP 2.25 0°C ≤ TA ≤ 85°C (Note 3) IFB Feedback Input Current ∆VFB Reference Voltage Line Regulation VIN = 2.5V to 5.5V (Note 3) VLOADREG Output Voltage Load Regulation Measured in Servo Loop, VITH = 0.36V Measured in Servo Loop, VITH = 0.84V VTRACK Tracking Voltage Offset VTRACK = 0.4V Tracking Voltage Range l 0.792 0.784 l l MAX UNITS 5.5 V 0.800 0.800 0.808 0.816 V V 100 200 nA 0.04 0.2 %/V 0.02 –0.02 0.2 –0.2 % % 15 mV 0.8 V 200 nA 0 ITRACK TRACK Input Current 100 ∆VPGOOD Power Good Range ±7.5 ±9 % RPGOOD Power Good Resistance 100 150 Ω IQ Input DC Bias Current Active Current Shutdown (Note 4) VFB = 0.7V, VITH = 1V VRUN = 0V 380 0.03 450 1.5 µA µA fOSC Switching Frequency Switching Frequency Range ROSC = 69.8kΩ (Note 6) 0.88 0.3 1 1.12 4 MHz MHz fSYNC SYNC Capture Range (Note 6) 0.3 4 MHz RPFET RDS(ON) of P-Channel FET ISW = 600mA 35 50 mΩ RNFET RDS(ON) of N-Channel FET ISW = – 600mA 25 35 mΩ ILIMIT Peak Current Limit VUVLO 12 17 Undervoltage Lockout Threshold 1.75 2 2.25 V VREF Reference Output 1.219 1.250 1.281 V ILSW SW Leakage Current 0.1 1 µA VRUN RUN Threshold 0.5 0.65 0.8 V VRUN = 0V, VIN = 5.5V Note 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 lifetime. Note 2: The LTC3418 is guaranteed to meet performance specifications from 0°C to 85°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. A Note 3: The LTC3418 is tested in a feedback loop that adjusts V FB to achieve a specified error amplifier output voltage (ITH). Note 4: Dynamic supply current is higher due to the internal gate charge being delivered at the switching frequency. Note 5: TJ is calculated from the ambient temperature TA and power dissipation PD as follows: LTC3418: TJ = TA + (PD)(34°C/W) Note 6: This parameter is guaranteed by design and characterization. 3418fc For more information www.linear.com/LTC3418 3 LTC3418 Typical Performance Characteristics Internal Reference Voltage vs Temperature Switch On-Resistance vs Input Voltage VIN = 3.3V 50 40 45 0.7985 0.7980 0.7975 0.7970 VIN = 3.3V 40 35 0.7990 ON-RESISTANCE (mΩ) REFERENCE VOLTAGE (V) 0.7995 On-Resistance vs Temperature 45 PFET 30 ON-RESISTANCE (mΩ) 0.8000 TA = 25°C unless otherwise noted. NFET 25 20 15 10 PFET 35 NFET 30 25 20 15 10 0.7965 5 5 0.7960 –40 –20 0 2.25 0 –40 –20 0 20 40 60 80 TEMPERATURE (°C) 100 120 2.75 3.25 3.75 4.25 4.75 INPUT VOLTAGE (V) 5.25 3418 G01 Quiescent Current vs Input Voltage 4500 4.5 450 4000 4.0 400 3.5 3.0 2.5 NFET PFET 0.5 0 2.25 3.25 3.75 4.25 4.75 INPUT VOLTAGE (V) 2.75 300 250 200 150 3 2.5 4 4.5 3.5 INPUT VOLTAGE (V) 960 940 100 1080 90 1040 1020 1000 980 960 920 920 900 –40 –20 900 2.25 100 120 3418 G07 4 100000 EFFICIENCY 10000 70 60 1000 POWER LOSS 100 50 40 10 30 2.75 3.25 3.75 4.25 4.75 INPUT VOLTAGE (V) 250 210 80 940 20 40 60 80 TEMPERATURE (°C) 130 170 ROSC (kΩ) 3418 G06 1100 EFFICIENCY (%) FREQUENCY (kHz) 980 90 Efficiency and Power Loss vs Load Current 1060 1000 50 5.25 3418 G08 20 0.01 POWER LOSS (mW) FREQUENCY (kHz) 1060 1020 10 3418 G05 VIN = 3.3V 0 0 5.5 5 Frequency vs Input Voltage 1040 1500 500 Frequency vs Temperature 1080 2000 50 3418 G04 1100 2500 1000 5.25 VIN = 3.3V 3000 100 0 Frequency vs ROSC 3500 350 FREQUENCY (kHz) QUIESCENT CURRENT (µA) LEAKAGE CURRENT (nA) 500 1.0 100 120 3418 G03 5.0 1.5 20 40 60 80 TEMPERATURE (°C) 3418 G02 Switch Leakage vs Input Voltage 2.0 0 VIN = 3.3V VOUT = 2.5V 0.1 1 LOAD CURRENT (A) 10 1 3418 G09 3418fc For more information www.linear.com/LTC3418 LTC3418 Typical Performance Characteristics Efficiency vs Load Current 100 Efficiency vs Load Current 50 40 30 20 70 60 50 40 30 20 VIN = 3.3V VOUT = 2.5V 10 0 0.01 FORCED CONTINUOUS VOUT = 2.5V 0 0.01 10 0.1 1 LOAD CURRENT (A) 3418 G10 10 –0.05 8 –0.10 ΔVOUT/VOUT (%) PEAK INDUCTOR CURRENT (A) 0 6 4 5V 0.1 0.2 0.3 0.4 0.5 VBCLAMP (V) 30 10 10 0.6 0.7 0.8 0 0.01 INDUCTOR CURRENT 5A/DIV –0.20 –0.30 VIN = 3.3V 20µs/DIV VOUT = 2.5V LOAD STEP: 800mA TO 8A 0 1 2 6 5 4 3 LOAD CURRENT (A) 7 3418 G15 8 3418 G14 Start-Up Transient OUTPUT VOLTAGE 100mV/DIV OUTPUT VOLTAGE 500mV/DIV INDUCTOR CURRENT 1A/DIV 3418 G16 10 3418 G12 Burst Mode Operation INDUCTOR CURRENT 5A/DIV 0.1 1 LOAD CURRENT (A) OUTPUT VOLTAGE 100mV/DIV –0.15 Load Step Transient OUTPUT VOLTAGE 100mV/DIV Burst Mode OPERATION VOUT = 2.5V Load Step Transient VIN = 3.3V VOUT = 1.8V f = 1MHz 3418 G13 VIN = 3.3V 40µs/DIV VOUT = 2.5V LOAD STEP: 3A TO 8A 40 –0.25 3.3V 0 50 Load Regulation 12 0 60 3418 G11 Peak Inductor Current vs Burst Clamp Voltage 2 70 20 10 0.1 1 LOAD CURRENT (A) 5V 80 5V EFFICIENCY (%) FORCED CONTINUOUS 60 3.3V 90 3.3V 80 EFFICIENCY (%) EFFICIENCY (%) 100 90 80 70 Efficiency vs Load Current 100 Burst Mode OPERATION 90 TA = 25°C unless otherwise noted. INDUCTOR CURRENT 2A/DIV VIN = 3.3V VOUT = 2.5V LOAD: 200mA 20µs/DIV 3418 G17 VIN = 3.3V VOUT = 2.5V LOAD: 8A 1ms/DIV 3418 G18 3418fc For more information www.linear.com/LTC3418 5 LTC3418 Pin Functions SW (Pins 1, 2, 11, 12, 20, 21, 30, 31): Switch Node Connection to Inductor. This pin connects to the drains of the internal main and synchronous power MOSFET switches. PVIN (Pins 3, 4, 9, 10, 22, 23, 28, 29): Power Input Supply. Decouple these pins to PGND with capacitors on all four corners of the package. PGOOD (Pin 5): Power Good Output. Open-drain logic output that is pulled to ground when the output voltage is not within ±7.5% of regulation point. VREF (Pin 16): Reference Output. Decouple this pin with a 2.2µF capacitor. SVIN (Pin 24): Signal Input Supply. Decouple this pin to SGND with a capacitor. VFB (Pin 25): Feedback Pin. Receives the feedback voltage from a resistive divider connected across the output. RT (Pin 6): Oscillator Resistor Input. Connecting a resistor to ground from this pin sets the switching frequency. ITH (Pin 26): Error Amplifier Compensation Point. The current comparator threshold increases with this control voltage. Nominal voltage range for this pin is from 0.2V to 1.4V with 0.4V corresponding to the zero-sense voltage (zero current). RUN/SS (Pin 7): Run Control and Soft-Start Input. Forcing this pin below 0.5V shuts down the LTC3418. In shutdown all functions are disabled drawing