LTC3412AEFE#TRPBF

LTC3412A 3A, 4MHz, Monolithic Synchronous Step-Down Regulator DESCRIPTION FEATURES High Efficiency: Up to 95% 3A Output Current n Low Quiescent Current: 64µA n Low R DS(ON) Internal Switch: 77mΩ n 2.25V to 5.5V Input Voltage Range n Programmable Frequency: 300kHz to 4MHz n ±2% Output Voltage Accuracy n 0.8V Reference Allows Low Output Voltage n Selectable Forced Continuous/Burst Mode® Operation with Adjustable Burst Clamp n Synchronizable Switching Frequency n Low Dropout Operation: 100% Duty Cycle n Power Good Output Voltage Monitor n Overtemperature Protected n Available in 16-Lead Exposed Pad TSSOP and QFN Packages n n APPLICATIONS Point-of-Load Regulation Notebook Computers n Portable Instruments n Distributed Power Systems n n The LTC®3412A 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 3A of output current. The internal synchronous power switch with 77mΩ on-resistance 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. 100% duty cycle provides low dropout operation extending battery life in portable systems. OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of loads and output capacitors. The LTC3412A 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 application requirements. L, LT, LTC, LTM, Burst Mode, OPTI-LOOP, Linear Technology and the Linear logo are registered trademarks and ThinSOT is a trademark of Analog Devices, Inc. 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 22µF VIN 3.3V Efficiency and Power Loss 100 PVIN SVIN PGND ITH SGND VFB SYNC/MODE VOUT 2.5V AT 3A COUT 100µF ×2 820pF 115k 69.8k 10000 90 0.47µH SW RUN/SS 100000 EFFICIENCY 85 75 100 70 65 60 392k 1000 80 POWER LOSS POWER LOSS (mW) 12.1k 1000pF PGOOD LTC3412A 294k EFFICIENCY (%) RT 2.2M 95 10 55 3412A F01a 50 0.01 Figure 1. 2.5V/3A Step-Down Regulator 0.1 1 LOAD CURRENT (A) 1 10 3412A F01b 3412aff For more information www.linear.com/LTC3412A 1 LTC3412A ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage..................................... –0.3V to 6V ITH, RUN/SS, VFB, PGOOD, SYNC/MODE Voltages.....................................–0.3 to VIN SW Voltages...................................–0.3V to (VIN + 0.3V) Operating Junction Temperature Range (Notes 2, 5) E-, I-Grades........................................– 40°C to 125°C MP-Grade...........................................– 55°C to 125°C Storage Temperature Range.....................–65°C to150°C Lead Temperature (Soldering, 10 sec)................... 300°C PIN CONFIGURATION 13 PGND 12 PGND SGND 2 4 RT 5 SYNC/MODE 6 RUN/SS 7 10 SW SGND 8 9 17 PVIN TAPE AND REEL 11 SVIN 17 10 PVIN SW 4 FE PACKAGE 16-LEAD PLASTIC TSSOP TJMAX = 125°C, θJA = 38°C/W, θJC = 10°C/W EXPOSED PAD (PIN 17) IS SGND, MUST BE SOLDERED TO PCB LEAD FREE FINISH 12 PGOOD PVIN 3 11 SW ORDER INFORMATION ITH 16 15 14 13 RUN/SS 1 VFB VFB 14 SW 9 5 6 7 8 SW 3 PGND 15 SW ITH SYNC/MODE 16 PVIN 2 SW 1 PGND SVIN PGOOD RT TOP VIEW TOP VIEW SW UF PACKAGE 16-LEAD (4mm × 4mm) PLASTIC QFN TJMAX = 125°C, θJA = 37°C/W, θJC = 5°C/W EXPOSED PAD (PIN 17) IS GND, MUST BE CONNECTED TO PCB http://www.linear.com/product/LTC3412A#orderinfo PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3412AEFE#PBF LTC3412AEFE#TRPBF 3412AEFE 16-Lead Plastic TSSOP –40°C to 125°C LTC3412AIFE#PBF LTC3412AIFE#TRPBF 3412AIFE 16-Lead Plastic TSSOP –40°C to 125°C LTC3412AEUF#PBF LTC3412AEUF#TRPBF 3412A 16-Lead (4mm × 4mm) Plastic QFN –40°C to 125°C LTC3412AIUF#PBF LTC3412AIUF#TRPBF 3412A 16-Lead (4mm × 4mm) Plastic QFN –40°C to 125°C LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3412AEFE LTC3412AEFE#TR 3412AEFE 16-Lead Plastic TSSOP –40°C to 125°C LTC3412AIFE LTC3412AIFE#TR 3412AIFE 16-Lead Plastic TSSOP –40°C to 125°C LTC3412AMPFE LTC3412AMPFE#TR 3412AMPFE 16-Lead Plastic TSSOP –55°C to 125°C LTC3412AEUF LTC3412AEUF#TR 3412A 16-Lead (4mm × 4mm) Plastic QFN –40°C to 125°C LTC3412AIUF LTC3412AIUF#TR 3412A 16-Lead (4mm × 4mm) Plastic QFN –40°C to 125°C 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: 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 3412aff For more information www.linear.com/LTC3412A LTC3412A ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at TA ≈ TJ = 25°C. VIN = 3.3V unless otherwise specified. SYMBOL PARAMETER SVIN Signal Input Voltage Range VFB Regulated Feedback Voltage CONDITIONS MIN TYP 2.25 (Note 3) E-, I-Grades MP-Grade l l 0.784 0.780 MAX UNITS 5.5 V 0.800 0.800 0.816 0.816 V V 0.1 0.2 µA IFB Voltage Feedback Leakage Current ∆VFB Reference Voltage Line Regulation VIN = 2.7V to 5.5V (Note 3) l 0.04 0.2 %V VLOADREG Output Voltage Load Regulation Measured in Servo Loop, VITH = 0.36V Measured in Servo Loop, VITH = 0.84V l l 0.02 –0.02 0.2 –0.2 % % ∆VPGOOD Power Good Range ±7.5 ±9 % RPGOOD Power Good Pull-Down Resistance 120 200 Ω IQ Input DC Bias Current Active Current Sleep Shutdown (Note 4) VFB = 0.78V, VITH = 1V VFB = 1V, VITH = 0V VRUN = 0V, VMODE = 0V 250 64 0.02 330 80 1 µA µA µA fOSC Switching Frequency Switching Frequency Range ROSC = 294kΩ (Note 6) 0.88 0.3 1 1.1 4 MHz MHz fSYNC SYNC Capture Range (Note 6) 0.3 4 MHz RPFET RDS(ON) of P-Channel FET ISW = 1A (Note 7) 77 110 mΩ RNFET RDS(ON) of N-Channel FET ISW = –1A (Note 7) 65 90 mΩ ILIMIT Peak Current Limit VUVLO Undervoltage Lockout Threshold ILSW SW Leakage Current VRUN RUN Threshold IRUN RUN/SS Leakage Current 4.5 1.75 VRUN = 0V, VIN = 5.5V 0.5 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 LTC3412AE is guaranteed to meet performance specifications from 0°C to 85°C. Specifications over the – 40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LTC3412AI is guaranteed to meet performance specifications over the –40°C to 125°C operating junction temperature range. The LTC3412AMP is guaranteed and tested to meet performance specifications over the full –55°C to 125°C operating junction temperature range. Note that the maximum ambient temperature consistent with these specifications is determined by specific operating conditions in conjunction with board layout, the rated package thermal resistance and other environmental factors. 6 A 2 2.25 V 0.1 1 µA 0.65 0.8 V 1 µA Note 3: The LTC3412A is tested in a feedback loop that adjusts VFB 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 as follows: LTC3412AFE: TJ = TA + PD (38°C/W) LTC3412AUF: TJ = TA + PD (34°C/W) Note 6: 4MHz operation is guaranteed by design and not production tested. Note 7: Switch on resistance is guaranteed by design and test condition in the UF package and by final test correlation in the FE package. 3412aff For more information www.linear.com/LTC3412A 3 LTC3412A TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs Load Current, Burst Mode Operation Efficiency vs Load Current 100 90 Burst Mode 80 OPERATION 95 70 85 50 40 30 0 0.01 75 70 65 50 0.01 FIGURE 4 CIRCUIT 95 1A EFFICIENCY (%) EFFICIENCY (%) 0.1A 86 3A 3.5 4.0 INPUT VOLTAGE (V) 4.5 5.0 93 0.47µH 91 90 10 3412A GO3 0 FIGURE 4 CIRCUIT VIN = 3.3V –0.1 –0.2 –0.3 –0.4 –0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 FREQUENCY (MHz) 3.5 4.0 –0.6 0 0.5 1.0 1.5 2.0 LOAD CURRENT (A) 3412A GO5 Burst Mode Operation 2.5 3.0 3412A GO6 Load Step Transient Burst Mode Operation Output Voltage Ripple BURST MODE 20mV/DIV VOUT 20mV/DIV 0.1 1 LOAD CURRENT (A) Load Regulation 92 87 VOUT = 2.5V FIGURE 4 CIRCUIT 0.22µH 3412A GO4 VOUT 100mV/DIV PULSE SKIPPING 20mV/DIV INDUCTOR CURRENT 1A/DIV FORCED CONTINUOUS 20mV/DIV FIGURE 4 CIRCUIT 5µs/DIV 3412A GO7 4 30 3412A GO2 88 3.0 40 0 0.01 10 89 82 80 2.5 50 10 FIGURE 4 CIRCUIT VIN = 3.3V 1µH 94 90 84 60 Efficiency vs Frequency 96 92 88 0.1 1 LOAD CURRENT (A) 3412A GO1 Efficiency vs Input Voltage 94 VIN = 5V 70 20 VOUT = 2.5V FIGURE 4 CIRCUIT 55 10 0.1 1 LOAD CURRENT (A) 80 60 VIN = 3.3V VOUT = 2.5V FIGURE 4 CIRCUIT 10 80 VIN = 5V ∆VOUT/VOUT (%) 20 VIN = 3.3V 90 EFFICIENCY (%) FORCED CONTINUOUS 60 100 VIN = 3.3V 90 EFFICIENCY (%) EFFICIENCY (%) 100 Efficiency vs Load Current, Forced Continuous Operation INDUCTOR CURRENT 2A/DIV VIN = 3.3V 5µs/DIV VOUT = 2.5V FIGURE 4 CIRCUIT 3412A GO8 VIN = 3.3V 40µs/DIV VOUT = 2.5V F = 1MHz LOAD STEP = 50mA TO 2A FIGURE 4 CIRCUIT 3412A GO9 3412aff For more information www.linear.com/LTC3412A LTC3412A TYPICAL PERFORMANCE CHARACTERISTICS Load Step Transient Forced Continuous Start-Up Transient VREF vs Temperature 0.7975 VOUT 100mV/DIV VIN = 3.3V 0.7970 VOUT 2V/DIV 0.7965 VREF (V) 0.7960 RUN/SS 2V/DIV INDUCTOR CURRENT 2A/DIV 0.7955 0.7950 0.7945 INDUCTOR CURRENT 2A/DIV 0.7940 0.7935 40µs/DIV VIN = 3.3V VOUT =2.5V f = 1MHz LOAD STEP = 0A TO 3A FIGURE 4 CIRCUIT 3412A G10 Switch On-Resistance vs Input Voltage 120 PFET 80 75 70 NFET 65 60 80 NFET 40 20 55 50 2.5 3.0 4.0 4.5 3.5 INPUT VOLTAGE (V) 0 20 40 60 80 TEMPERATURE (°C) Frequency vs ROSC VIN = 3.3V 3500 3000 2500 2000 1500 1000 15 10 40 140 240 340 440 540 640 740 840 940 ROSC (kΩ) 3412A G16 NFET 2.5 3.0 4.0 4.5 3.5 INPUT VOLTAGE (V) 5.5 Frequency vs Temperature VIN = 3.3V 1015 ROSC = 294k ROSC = 294k 1010 1040 1030 1020 1010 990 2.5 5.0 1020 1005 1000 995 990 985 980 1000 500 PFET 20 3412A G15 1050 FREQUENCY (kHz) FREQUENCY (kHz) 25 Frequency vs Input Voltage 1060 4000 0 30 3412A G14 FREQUENCY (kHz) 4500 35 0 100 120 3412A G13 5000 40 5 0 –40 –20 5.0 115 45 PFET 60 95 50 SWITCH LEAKAGE CURRENT (nA) ON-RESISTANCE (mΩ) 85 15 35 55 75 TEMPERATURE (°C) Switch Leakage Current vs Input Voltage 100 90 –5 3412A G12 VIN = 3.3V 95 –45 –25 3412A G11 Switch On-Resistance vs Temperature 100 ON-RESISTANCE (mΩ) 0.7930 1ms/DIV VIN = 3.3V VOUT =2.5V LOAD STEP = 2A FIGURE 4 CIRCUIT 975 3.0 4.0 4.5 3.5 INPUT VOLTAGE (V) 5.0 5.5 3412A G17 970 –40 –20 0 20 40 60 80 TEMPERATURE (°C) 100 120 3412A G18 3412aff For more information www.linear.com/LTC3412A 5 LTC3412A TYPICAL PERFORMANCE CHARACTERISTICS Quiescent Current vs Input Voltage Quiescent Current vs Temperature 350 350 VIN = 3.3V 300 ACTIVE QUIESCENT CURRENT (µA) QUIESCENT CURRENT (µA) 300 250 200 150 100 SLEEP 50 ACTIVE 250 200 150 100 SLEEP 50 0 2.5 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) 5.0 0 –40 –20 5.5 0 20 40 60 80 3412A G20 3412A G19 Peak Current vs Input Voltage 4000 8.0 3500 7.5 PEAK INDUCTOR CURRENT (A) MAXIMUM PEAK INDUCTOR CURRENT (mA) Minimum Peak Inductor Current vs Burst Clamp Voltage 3000 2500 2000 1500 1000 500 0 0.1 7.0 6.5 6.0 5.5 5.0 4.5 0.2 0.3 0.4 0.5 0.6 0.7 VBURST (V) 4.0 2.25 2.75 3412A G21 6 100 120 TEMPERATURE (°C) 3.25 3.75 4.25 INPUT VOLTAGE (V) 4.75 3412A G22 3412aff For more information www.linear.com/LTC3412A LTC3412A PIN FUNCTIONS (FE/UHF) SVIN (Pin 1/Pin 11): Signal Input Supply. Decouple this pin to SGND with a capacitor. PGOOD (Pin 2/Pin 12): Power Good Output. Open-drain logic output that is pulled to ground when the output voltage is not within ±7.5% of regulation point. ITH (Pin 3/Pin 13): 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). VFB (Pin 4/Pin 14): Feedback Pin. Receives the feedback voltage from a resistive divider connected across the output. RT (Pin 5/Pin 15): Oscillator Resistor Input. Connecting a resistor to ground from this pin sets the switching frequency. SYNC/MODE (Pin 6/Pin 16): Mode Select and External Clock Synchronization Input. To select forced continuous, tie to SVIN. Connecting this pin to a voltage between 0V and 1V selects Burst Mode operation with the burst clamp set to the pin voltage. RUN/SS (Pin 7/Pin 1): Run Control and Soft-Start Input. Forcing this pin below 0.5V shuts down the LTC3412A. In shutdown all functions are disabled drawing