LTC3633

LTC3633 1 3633f n 3.6V to 15V Input Voltage Range n 3A Output Current per Channel n Up to 95% Effi ciency n Low Duty Cycle Operation: 5% at 2.25MHz n Selectable 0°/180° Phase Shift Between Channels n Adjustable Switching Frequency: 500kHz to 4MHz n External Frequency Synchronization n Current Mode Operation for Excellent Line and Load Transient Response n 0.6V Reference Allows Low Output Voltages n User Selectable Burst Mode® Operation or Forced Continuous Operation n Output Voltage Tracking and Soft-Start Capability n Short-Circuit Protected n Overvoltage Input and Overtemperature Protection n Low Power 2.5V Linear Regulator Output n Power Good Status Outputs n Available in (4mm × 5mm) QFN-28 and 28-Lead TSSOP Packages TYPICAL APPLICATION DESCRIPTION Dual Channel 3A, 15V Monolithic Synchronous Step-Down Regulator The LTC®3633 is a high effi ciency, dual-channel monolithic synchronous buck regulator using a controlled on-time, current mode architecture, with phase lockable switching frequency. The two channels can run 180° out of phase, which relaxes the requirements for input and output ca- pacitance. The operating supply voltage range is from 3.6V to 15V, making it suitable for dual cell lithium-ion batteries as well as point of load power supply applications from a 12V or 5V supply. The operating frequency is programmable and synchroniz- able from 500kHz to 4MHz with an external resistor. The high frequency capability allows the use of small surface mount inductors and capacitors. The unique constant frequency/controlled on-time architecture is ideal for high step-down ratio applications that operate at high frequency while demanding fast transient response. An internal phase lock loop servos the on-time of the internal one-shot timer to match the frequency of the internal clock or an applied external clock. The LTC3633 can select between forced continuous mode and high effi ciency Burst Mode operation. FEATURES APPLICATIONS n Distributed Power Systems n Battery Powered Instruments n Point of Load Power Supplies Effi ciency vs Load Current L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 5847554, 6580258, 6304066, 6476589, 6774611. 1 0 EF FI CI EN CY (% ) 10 30 40 50 70 100 10000 3633 TA01b 20 80 100 90 60 10 1000 VOUT = 5V VOUT = 3.3V LOAD CURRENT (mA) Burst Mode OPERATION VIN = 12V RUN1 RUN2 TRACKSS2 PGOOD2 LTC3633 BOOST2 0.1μF1.5μH 73.2k 10k SW2 VON2 VIN2 PGNDSGND VIN1 VFB2 PHMODE TRACKSS1 PGOOD1 BOOST1 SW1 VON1 VFB1 22μF VOUT2 5V AT 3A 0.1μF 1μH 45.3k 10k 22μF VOUT1 3.3V AT 3A VIN 3.6V TO 15V 47μF x2 MODE/SYNC V2P5 RT ITH1 ITH2 INTVCC 2.2μF 3633 TA01a LTC3633 2 3633f PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS VIN1, VIN2 ................................................... –0.3V to 16V VIN1, VIN2 Transient ...................................................18V PGOOD1, PGOOD2, VON1, VON2 ................. –0.3V to 16V BOOST1, BOOST2 ................................... –0.3V to 19.6V BOOST1-SW1, BOOST2-SW2 ................... –0.3V to 3.6V V2P5, INTVCC, TRACKSS1, TRACKSS2 ...... –0.3V to 3.6V ITH1, ITH2, REXT, MODE/SYNC .... –0.3V to INTVCC + 0.3V (Note 1) ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3633EUFD#PBF LTC3633EUFD#TRPBF 3633 28-Lead (4mm × 5mm) Plastic QFN –40°C to 125°C LTC3633IUFD#PBF LTC3633IUFD#TRPBF 3633 28-Lead (4mm × 5mm) Plastic QFN –40°C to 125°C LTC3633EFE#PBF LTC3633EFE#TRPBF LTC3633FE 28-Lead Plastic TSSOP –40°C to 125°C LTC3633IFE#PBF LTC3633IFE#TRPBF LTC3633FE 28-Lead Plastic TSSOP –40°C to 125°C Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based fi nish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifi cations, go to: http://www.linear.com/tapeandreel/ VFB1, VFB2, PHMODE. .................. –0.3V to INTVCC + 0.3V RUN1, RUN2 .................................... –0.3V to VIN + 0.3V SW1, SW2 ....................................... –0.3V to VIN + 0.3V SW Source and Sink Current (DC) (Note 2) ................3A Operating Junction Temperature Range (Note 3) .................................................. –40°C to 125°C Storage Temperature Range ................... –65°C to 125°C 9 10 TOP VIEW UFD PACKAGE 28-LEAD (4mm × 5mm) PLASTIC QFN 11 12 13 28 27 26 25 24 14 23 6 5 4 3 2 1PGOOD1 PHMODE RUN1 MODE/SYNC RT RUN2 SGND PGOOD2 VIN1 VIN1 BOOST1 INTVCC V2P5 BOOST2 VIN2 VIN2 V F B1 TR AC KS S1 IT H1 V O N1 SW 1 SW 1 V F B2 TR AC KS S2 IT H2 V O N2 SW 2 SW 2 7 17 18 19 20 21 22 16 8 15 29 PGND 1 2 3 4 5 6 7 8 9 10 11 12 13 14 TOP VIEW FE PACKAGE 28-LEAD PLASTIC TSSOP 28 27 26 25 24 23 22 21 20 19 18 17 16 15 ITH1 TRACKSS1 VFB1 PGOOD1 PHMODE RUN1 MODE/SYNC RT RUN2 SGND PGOOD2 VFB2 TRACKSS2 ITH2 VON1 SW1 SW1 VIN1 VIN1 BOOST1 INTVCC V2P5 BOOST2 VIN2 VIN2 SW2 SW2 VON2 29 PGND TJMAX = 125°C, θJA = 43°C/W EXPOSED PAD (PIN 29) IS PGND, MUST BE SOLDERED TO PCB TJMAX = 125°C, θJA = 25°C/W EXPOSED PAD (PIN 29) IS PGND, MUST BE SOLDERED TO PCB LTC3633 3 3633f ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VIN Supply Range l 3.6 15 V IQ Input DC Supply Current (VIN1 + VIN2) Both Channels Active (Note 5) Sleep Current Shutdown MODE = 0V MODE = INTVCC, VFB1, VFB2 > 0.6 RUN = 0V 1.3 500 13 mA μA μA VFB Feedback Reference Voltage l 0.594 0.6 0.606 V ΔVLINE_REG Reference Voltage Line Regulation VIN = 3.6V to 15V 0.02 %/V ΔVLOAD_REG Output Voltage Load Regulation ITH = 0.8V to 1.6V 0.05 % IFB Feedback Pin Input Current ±30 nA gm(EA) Error Amplifi er Transconductance ITH = 1.2V 1.8 mS tON Minimum On Time VON = 1V, VIN = 4V 20 ns tOFF Minimum Off Time VIN = 6V 40 60 ns fOSC Oscillator Frequency VRT = INTVCC RT = 160k RT = 80k 1.4 1.7 3.4 2 2 4 2.6 2.3 4.6 MHz MHz MHz ILIM Valley Switch Current Limit Channel 1 (3A) Channel 2 (3A) 2.6 2.6 3.5 3.5 4.5 4.5 A A RDS(ON) Channel 1 Top Switch On-Resistance Bottom Switch On-Resistance Channel 2 Top Switch On-Resistance Bottom Switch On-Resistance 130 65 130 65 mΩ mΩ mΩ mΩ ISW(LKG) Switch Leakage Current VIN = 15V, VRUN = 0V 0.01 ±1 μA VVIN-OV VIN Overvoltage Lockout Threshold VIN Rising VIN Falling 16.8 15.8 17.5 16.5 18 17 V V INTVCC Voltage 3.6V < VIN < 15V, 0mA Load 3.1 3.3 3.5 V INTVCC Load Regulation 0mA to 50mA Load, VIN = 4V to 15V 0.7 % RUN Threshold Rising RUN Threshold Falling l l 1.18 0.98 1.22 1.01 1.26 1.04 V V RUN Leakage Current VIN = 15V 0 ±3 μA V2P5 Voltage ILOAD = 0mA to 10mA l 2.46 2.5 2.54 V PGOOD Good-to-Bad Threshold VFB Rising VFB Falling 8 –8 10 –10 % % PGOOD Bad-to-Good Threshold VFB Falling VFB Rising –3 3 –5 5 % % RPGOOD PGOOD Pull-Down Resistance 10mA Load 15 Ω tPGOOD Power Good Filter Time 20 40 μs tSS Internal Soft-Start Time 400 700 μs VFB During Tracking TRACKSS = 0.3V 0.28 0.3 0.315 V ITRACKSS TRACKSS Pull-Up Current 1.4 μA VPHMODE PHMODE Threshold Voltage PHMODE VIH PHMODE VIL 1 0.3 V V The l denotes the specifi cations which apply over the full operating junction temperature range, otherwise specifi cations are at TJ = 25°C. VIN = 12V, INTVCC = 3.3V, unless otherwise noted. LTC3633 4 3633f ELECTRICAL CHARACTERISTICS 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: Guaranteed by long term current density limitations. Note 3: The LTC3633E is guaranteed to meet specifi ed performance from 0°C to 85°C. Specifi cations over the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LTC3633I is guaranteed to meet SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VMODE/SYNC MODE/SYNC Threshold Voltage MODE VIH MODE VIL 1 0.4 V V SYNC Threshold Voltage SYNC VIH 0.95 V IMODE MODE/SYNC Input Current MODE = 0V MODE = INTVCC 1.5 –1.5 μA μA The l denotes the specifi cations which apply over the full operating junction temperature range, otherwise specifi cations are at TJ = 25°C. VIN = 12V, INTVCC = 3.3V, unless otherwise noted. specifi cations over the full –40°C to 125°C operating junction temperature range Note 4: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C when overtemperature protection is active. Continuous operation above the specifi ed maximum operating junction temperature may impair device reliability. Note 5: Dynamic supply current is higher due to the internal gate charge being delivered at the switching frequency. LTC3633 5 3633f TYPICAL PERFORMANCE CHARACTERISTICS Effi ciency vs Load Current Effi ciency vs Input Voltage Burst Mode Operation Load Regulation Oscillator Frequency vs Temperature Effi ciency vs Load Current Burst Mode Operation Effi ciency vs Load Current Forced Continuous Mode Operation Effi ciency vs Load Current TJ = 25°C, VIN = 12V, fSW = 1MHz, L = 1μH unless otherwise noted. Oscillator Internal Set Frequency vs Temperature Reference Voltage vs Temperature 1 0 EF FI CI EN CY (% ) 10 30 40 50 70 100 10000 3633 G01 20 80 100 90 60 10 1000 VIN = 4V VIN = 8V VIN = 12V LOAD CURRENT (mA) VOUT = 1.8V 1 0 EF FI CI EN CY (% ) 10 30 40 50 70 100 10000 3633 G02 20 80 100 90 60 10 1000 VIN = 4V VIN = 8V VIN = 12V LOAD CURRENT (mA) VOUT = 1.8V 1 0 EF FI CI EN CY (% ) 10 30 40 50 70 100 10000 3633 G03 20 80 100 90 60 10 1000 VOUT = 5V VOUT = 3.3V LOAD CURRENT (mA) Burst Mode OPERATION FORCED CONTINUOUS OPERATION 4 EF FI CI EN CY (% ) 65 70 75 85 8 16 3633 G05 60 90 100 95 80 6 10 12 14 ILOAD = 10mA ILOAD = 100mA ILOAD = 1A ILOAD = 3A INPUT VOLTAGE (V) 0.1 1 0 EF FI CI EN CY (% ) 10 30 40 50 70 100 10000 3633 G04 20 80 100 90 60 10 1000 LOAD CURRENT (mA) VIN = 4V VIN = 8V VIN = 12V VIN = 15V –50 V F B (V ) 0.597 0.599 50 150 3633 G06 0.595 0.601 0.605 0.603 25–25 0 75 100 125 TEMPERATURE (°C) 0 ΔV OU T/ V O UT (% ) 0.0 0.4 1.5 3 3633 G07 –0.4 0.8 1.6 1.2 10.5 2 2.5 ILOAD (A) Burst Mode OPERATION FORCED CONTINUOUS –50 FR EQ UE NC Y VA RI AT IO N (% ) –8 –6 –4 –2 0 2 4 6 8 25 125 3633 G08 –10 10 0–25 50 75 100 TEMPERATURE (°C) –50 FR EQ UE NC Y (M Hz ) 1.6 1.8 2.0 2.2 2.4 25 125 3633 G09 1.4 2.6 0–25 50 75 100 TEMPERATURE (°C) RT = INTVCC LTC3633 6 3633f Burst Mode Operation Internal MOSFET RDS(ON) vs Temperature Quiescent Current vs VIN Burst Mode Operation Switch Leakage vs Temperature Valley Current Limit vs Temperature Track Pull-Up Current vs Temperature TYPICAL PERFORMANCE CHARACTERISTICS Shutdown Current vs VIN V2P5 Load Regulation Load Step 4 I Q (μ A) 100 200 300 500 8 16 3633 G11 0 600 800 700 400 6 10 12 14 TA = 90°C TA = 25°C TA = –40°C VIN (V) 4 I Q (μ A) 2 4 6 10 8 16 3633 G12 0 12 20 16 18 14 8 6 10 12 14 VIN (V) –50 LE AK AG E CU RR EN T (n A) 1000 2000 3000 5000 0 125100 3633 G13 0 6000 7000 4000 –25 25 50 75 TEMPERATURE (°C) MAIN SWITCH SYNCHRONOUS SWITCH TJ = 25°C, VIN = 12V, fSW = 1MHz, L = 1μH unless otherwise noted. TEMPERATURE (°C) –50 1.4 1.6 2.0 25 75 3633 G15 1.2 1.0 –25 0 50 100 125 0.8 0.6 1.8 I T RA CK (μ A) –50 I L IM (A ) 3.4 3.5 50 3633 G14 3.3 3.7 3.6 3.9 3.8 25–25 0 75 100 125 TEMPERATURE (°C) 0 V2 P5 (V ) 2.496 2.498 6 3633 G16 2.494 2.502 2.500 2.506 2.504 42 8 10 ILOAD (mA) IL 1A/DIV SW 10V/DIV 5μs/DIV 3633 G17 VOUT 50mV/DIV VOUT = 1.8V ILOAD = 100mA IL 2A/DIV 20μs/DIV 3633 G18 VOUT AC-COUPLED 100mV/DIV VOUT = 1.8V ILOAD = 100mA to 3A CITH = 220pF RITH = 13kΩ –50 R D S( ON ) ( Ω ) 20 40 60 80 100 120 140 25 125 3633 G10 0 160 0–25 50 75 100 TEMPERATURE (°C) TOP SWITCH BOTTOM SWITCH LTC3633 7 3633f TYPICAL PERFORMANCE CHARACTERISTICS Start-Up into Prebiased Output (Forced Continuous Mode) Load Step (Internal Compensation) Start-Up into Prebiased Output (Burst Mode Operation) Start-Up (Burst Mode Operation) TJ = 25°C, VIN = 12V, fSW = 1MHz, L = 1μH unless otherwise noted. Start-Up (Forced Continuous Mode) IL 2A/DIV 20μs/DIV 3633 G19 VOUT AC-COUPLED 100mV/DIV VOUT = 1.8V ILOAD = 100mA to 3A ITH = INTVCC IL 2A/DIV 400μs/DIV 3633 G20 RUN 2V/DIV VOUT 1V/DIV CSS = 4.7nF ILOAD = 150mA IL 1A/DIV 400μs/DIV 3633 G21 RUN 2V/DIV VOUT 1V/DIV CSS = 4.7nF ILOAD = 150mA IL 1A/DIV 200μs/DIV 3633 G22 RUN 2V/DIV VOUT 1.8V 1V/DIV ILOAD = 0mA IL 2A/DIV 1ms/DIV 3633 G22 RUN 2V/DIV VOUT 1.8V 1V/DIV ILOAD = 0mA LTC3633 8 3633f PIN FUNCTIONS PGOOD1 (Pin 1/Pin 4): Channel 1 Open-Drain Power Good Output Pin. PGOOD1 is pulled to ground when the voltage on the VFB1 pin is not within ±8% (typical) of the internal 0.6V reference. PGOOD1 becomes high imped- ance once the VFB1 pin returns to within ±5% (typical) of the internal reference. PHMODE (Pin 2/Pin 5): Phase Select Input. Tie this pin to ground to force both channels to switch in phase. Tie this pin to INTVCC to force both channels to switch 180° out of phase. Do not fl oat this pin. RUN1 (Pin 3/Pin 6): Channel 1 Regulator Enable Pin. Enables channel 1 operation by tying RUN above 1.22V. Tying it below 1V places the part into shutdown. Do not fl oat this pin. MODE/SYNC (Pin 4/Pin 7): Mode Select and External Synchronization Input. Tie this pin to ground to force continuous synchronous operation at all output loads. Floating this pin or tying it to INTVCC enables high effi ciency Burst Mode operation at light loads. Drive this pin with a clock to synchronize the LTC3633 switching. An internal phase-locked loop will force the bottom power NMOS’s turn on signal to be synchronized with the rising edge of the CLKIN signal. When this pin is driven with a clock, forced continuous mode is automatically selected. RT (Pin 5/Pin 8): Oscillator Frequency Program Pin. Connect an external resistor (between 80k to 640k) from this pin to SGND in order to program the frequency from 500kHz to 4MHz. When RT is tied to INTVCC, the switching frequency will default to 2MHz. RUN2 (Pin 6/Pin 9): Channel 2 Regulator Enable Pin. Enables channel 2 operation by tying RUN above 1.22V. Tying it below 1V places the part into shutdown. Do not fl oat this pin. SGND (Pin 7/Pin 10): Signal Ground Pin. This pin should have a low noise connection to reference ground. The feedback resistor network, external compensation network, and RT resistor should be connected to this ground. PGOOD2 (Pin 8/Pin 11): Channel 2 Open-Drain Power Good Output Pin. PGOOD2 is pulled to ground when the voltage on the VFB2 pin is not within 8% (typical) of the internal 0.6V reference. PGOOD2 becomes high imped- ance once the VFB2 pin returns to within ±5% (typical) of the internal reference. VFB2 (Pin 9/Pin 12): Channel 2 Output Feedback Voltage Pin. Input to the error amplifi er that compares the feedback voltage to the internal 0.6V reference voltage. Connect this pin to a resistor divider network to program the desired output voltage. TRACKSS2 (Pin 10/Pin 13): Output Tracking and Soft-Start Input Pin for Channel 2. Forcing a voltage below 0.6V on this pin bypasses the internal reference input to the error amplifi er. The LTC3633 will servo the FB pin to the TRACK voltage under this condition. Above 0.6V, the tracking func- tion stops and the internal reference resumes control of the error amplifi er. An internal 1.4μA pull up current from INTVCC allows a soft start function to be implemented by connecting a capacitor between this pin and SGND. ITH2 (Pin 11/Pin 14): Channel 2 Error Amplifi er Output and Switching Regulator Compensation Pin. Connect this pin to appropriate external components to compensate the regulator loop frequency response. Connect this pin to INTVCC to use the default internal compensation. VON2 (Pin 12/Pin 15): On-Time Voltage Input for Chan- nel 2. This pin sets the voltage trip point for the on-time comparator. Tying this pin to the output voltage makes the on-time proportional to VOUT2 when VOUT2 < 6V. When VOUT2 > 6V, switching frequency may become higher than the set frequency. The pin impedance is nominally 180kΩ. SW2 (Pins 13, 14/Pins 16, 17): Channel 2 Switch Node Connection to External Inductor. Voltage swing of SW is from a diode voltage drop below ground to VIN. VIN2 (Pins 15, 16/Pins 18, 19): Power Supply Input for Channel 2. Input voltage to the on chip power MOSFETs on channel 2. This input is capable of operating from a different supply voltage than VIN1. BOOST2 (Pin 17/Pin 20): Boosted Floating Driver Supply for Channel 2. The (+) terminal of the bootstrap capacitor connects to this pin while the (–) terminal connects to the SW pin. The normal operation voltage swing of this pin ranges from a diode voltage drop below INTVCC up to VIN+INTVCC. (QFN/TSSOP) LTC3633 9 3633f PIN FUNCTIONS V2P5 (Pin 18/Pin 21): 2.5V Regulator Output. Outputs a regulated 2.5V supply voltage capable of supplying 10mA. Bypass this pin with a minimum of 1μF low ESR ceramic capacitor. Tie this pin to INTVCC when this output is not being used in the application. INTVCC (Pin 19/Pin 22): Internal 3.3V Regulator Output. The internal power drivers and control circuits are powered from this voltage. Decouple this pin to power ground with a minimum of 1μF low ESR ceramic capacitor. BOOST1 (Pin 20/Pin 23): Boosted Floating Driver Supply for Channel 1. The (+) terminal of the bootstrap capacitor connects to this pin while the (–) terminal connects to the SW pin. The normal operation voltage swing of this pin ranges from a diode voltage drop below INTVCC up to VIN + INTVCC. VIN1 (Pins 21,22/Pins 24, 25): Power Supply Input for Channel 1. Input voltage to the on chip power MOSFETs on channel 1. The internal LDO for INTVCC is powered off of this pin. SW1 (Pins 23,24/Pins 26, 27): Channel 1 Switch Node Connection to External Inductor. Voltage swing of SW is from a diode voltage drop below ground to VIN. VON1 (Pin 25/Pin 28): On-Time Voltage Input for Chan- nel 1. This pin sets the voltage trip point for the on-time comparator. Tying this pin to the regulated output volt- age makes the on-time proportional to VOUT1 when VOUT1 < 6V. When VOUT1 > 6V, switching frequency may become higher than the set frequency. The pin impedance is nominally 180kΩ. ITH1 (Pin 26/Pin 1): Channel 1 Error Amplifi er Output and Switching Regulator Compensation Pin. Connect this pin to appropriate external components to compensate the regulator loop frequency response. Connect this pin to INTVCC to use the default internal compensation. TRACKSS1 (Pin 27/Pin 2): Output Tracking and Soft-Start Input Pin for Channel 1. Forcing a voltage below 0.6V on this pin bypasses the internal reference input to the error amplifi er. The LTC3633 will servo the FB pin to the TRACK voltage. Above 0.6V, the tracking function stops and the internal reference resumes control of the error amplifi er. An internal 1.4μA pull up current from INTVCC allows a soft-start function to be implemented by connecting a capacitor between this pin and SGND. VFB1 (Pin 28/Pin 3): Channel 1 Output