LTM4601HV LINER | Alldatasheet
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 28
Technical content
12A 28VIN DC/DC µModule with PLL, Output Tracking and Margining ■ Telecom and Networking Equipment ■ Servers ■ Industrial Equipment ■ Point of Load Regulation ■ Complete Switch Mode Power Supply ■ Wide Input Voltage Range: 4.5V to 28V ■ 12A DC Typical, 14A Peak Output Current ■ 0.6V to 5V Output Voltage ■ Output Voltage Tracking and Margining ■ Parallel Multiple µModulesTM for Current Sharing ■ Differential Remote Sensing for Precision Regulation ■ PLL Frequency Synchronization ■ ± 1.5% Regulation ■ Current Foldback Protection (Disabled at Start-Up) ■ Pb-Free (e4) RoHS Compliant Package with Gold Finish Pads ■ Ultrafast Transient Response ■ Current Mode Control ■ Up to 95% Effi ciency at 5VIN, 3.3VOUT ■ Programmable Soft-Start ■ Output Overvoltage Protection ■ Small Footprint, Low Profi le (15mm × 15mm × 2.8mm) Surface Mount LGA Package 2.5V/12A Power Supply with 4.5V to 28V Input APPLICATIO SU FEATURES DESCRIPTIO U TYPICAL APPLICATIO U Effi ciency and Power Loss vs Load Current The LTM®4601HV is a complete 12A step-down switch mode DC/DC power supply with onboard switching con- troller, MOSFETs, inductor and all support components. The µModule is housed in a small surface mount 15mm ×15mm × 2.8mm LGA package. Operating over an input voltage range of 4.5 to 28V, the LTM4601HV supports an output voltage range of 0.6V to 5V as well as output voltage tracking and margining. The high effi ciency design delivers 12A continuous current (14A peak). Only bulk input and output capacitors are needed to complete the design. The low profi le (2.8mm) and light weight (1.7g) package easily mounts in unused space on the back side of PC boards for high density point of load regulation. The µModule can be synchronized with an external clock for reducing undesirable frequency harmonics and allows PolyPhase ® operation for high load currents. A high switching frequency and adaptive on-time current mode architecture deliver a very fast transient response to line and load changes without sacrifi cing stability. An onboard differential remote sense amplifi er can be used to accurately regulate an output voltage independent of load current. VOUT VFB MARG0 MARG1 VOUT_LCL DIFFVOUT VOSNS+ VOSNS– PGOOD RUN COMP INTV CC DRVCC MPGM TRACK/SSPLLIN LTM4601HV ON/OFF 392k RSET 19.1k MARGIN CONTROL COUT 4601HV TA01a VOUT 2.5V 12A CLOCK SYNC TRACK/SS CONTROL 100pF CIN VIN fSETPGNDSGND 5% MARGIN VIN 4.5V TO 28V LOAD CURRENT (A) EFFICIENCY (%) POWER LOSS (W) 12VIN 12VIN 24VIN 24VIN 4 8 10 4601HV TA01b 2 6 12 14 POWER LOSS EFFICIENCY , LT, LTC, LTM and PolyPhase are registered trademarks of Linear Technology Corporation. µModule is a trademark 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, 6677210
INTVCC, DRVCC, VOUT_LCL, VOUT (VOUT ≤ 3.3V with PLLIN, TRACK/SS, MPGM, MARG0, MARG1, PGOOD, f V Operating Temperature Range (Note 2) ... –40°C to 85°C (Note 1) The ● denotes the specifi cations which apply over the –40°C to 85°C temperature range, otherwise specifi cations are at TA = 25°C, VIN = 12V. Per typical application (front page) confi guration.
ELECTRICAL CHARACTERISTICS
ABSOLUTE AXI U RATI GSW WW U PACKAGE/ORDER I FOR ATIOUU W SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VIN(DC) Input DC Voltage ● 4.5 28 V VOUT(DC) Output Voltage (With Remote Sense Amp) CIN = 10µF ×3, COUT = 200µF V IN = 12V, VOUT = 1.5V, IOUT = 0 ● 1.478 1.5 1.522 V Input Specifi cations VIN(UVLO) Undervoltage Lockout Threshold I OUT = 0A 3.2 4 V IINRUSH(VIN) Input Inrush Current at Startup I OUT = 0A. VOUT = 1.5V V IN = 5V V IN = 12V 0.6 0.7 A A IQ(VIN,NO LOAD) Input Supply Bias Current V IN = 12V, VOUT = 1.5V, No Switching VIN = 12V, VOUT = 1.5V, Switching Continuous V IN = 5V, VOUT = 1.5V, No Switching VIN = 5V, VOUT = 1.5V, Switching Continuous Shutdown, RUN = 0, VIN = 12V 3.8 2.5 mA mA mA mA µA I S(VIN) Input Supply Current V IN = 12V, VOUT = 1.5V, IOUT = 12A VIN = 12V, VOUT = 3.3V, IOUT = 12A VIN = 5V, VOUT = 1.5V, IOUT = 12A 1.81 3.63 4.29 A A A INTV CC VIN = 12V, RUN > 2V No Load 4.7 5 5.3 V MARG1 DRVCC VFB PGOOD SGND V OSNS+ DIFFVOUT VOUT_LCL VOSNS– VIN PGND VOUT fSET MARG0 RUN COMP MPGM PLLIN INTVCC TRACK/SS LGA PACKAGE 118-LEAD (15mm /KB4 15mm /KB4 2.8mm) TOP VIEW TJMAX = 125°C, θJA = 15°C/W, θJC = 6°C/W, θJA DERIVED FROM 95mm × 76mm PCB WITH 4 LAYERS WEIGHT = 1.7g ORDER PART NUMBER LGA PART MARKING* LTM4601HVEV#PBF LTM4601HVIV#PBF LTM4601HVV LTM4601HVV 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.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Output Specifi cations I OUTDC Output Continuous Current Range (See Output Current Derating Curves for Different V IN, VOUT and TA) VIN = 12V, VOUT = 1.5V 0 12 A ΔVOUT(LINE) VOUT Line Regulation Accuracy V OUT = 1.5V, IOUT = 0A, VIN = 4.5V – 28V ● 0.3 % ΔVOUT(0-12A) VOUT Load Regulation Accuracy V OUT = 1.5V, IOUT = 0A to 12A, with RSA V IN = 5V V IN = 12V 0.25 0.25 VOUT(AC) Output Ripple Voltage I OUT = 0A, COUT = 2×, 100µF/X5R/Ceramic VIN = 12V, VOUT = 1.5V VIN = 5V, VOUT = 1.5V mVP-P mVP-P fS Output Ripple Voltage Frequency I OUT = 5A, VIN = 12V, VOUT = 1.5V 850 kHz ΔVOUT(START) Turn-On Overshoot, TRACK/SS = 10nF COUT = 200µF, VOUT = 1.5V, IOUT = 0A VIN = 12V VIN = 5V mV mV tSTART Turn-On Time, TRACK/SS = Open C OUT = 200µF, VOUT = 1.5V, IOUT = 1A Resisitive Load V IN = 12V VIN = 5V 0.5 0.7 ms ms ΔVOUTLS Peak Deviation for Dynamic Load Load: 0% to 50% to 0% of Full Load, COUT = 2 × 22µF/Ceramic, 470µF, 4V Sanyo POSCAP V IN = 12V VIN = 5V mV mV tSETTLE Settling Time for Dynamic Load Step Load: 0% to 50%, or 50% to 0% of Full Load VIN = 12V 25 µs IOUTPK Output Current Limit C OUT = 200µF, Table 2 VIN = 12V, VOUT = 1.5V VIN = 5V, VOUT = 1.5V A A Remote Sense Amp (Note 3) VOSNS+, VOSNS– CM Range Common Mode Input Voltage Range V IN = 12V, RUN > 2V 0 INTV CC – 1 V DIFFVOUT Range Output Voltage Range V IN = 12V, DIFF OUT Load = 100k 0 INTV CC V VOS Input Offset Voltage Magnitude 1.25 mV AV Differential Gain 1V / V GBP Gain Bandwidth Product 3M H z SR Slew Rate 2 V/µs RIN Input Resistance V OSNS+ to GND 20 k Ω CMRR Common Mode Rejection Mode 100 dB Control Stage V FB Error Amplifi er Input Voltage Accuracy IOUT = 0A, VOUT = 1.5V ● 0.594 0.6 0.606 V VRUN RUN Pin On/Off Threshold 1 1.5 1.9 V ISS/TRACK Soft-Start Charging Current V SS/TRACK = 0V –1.0 –1.5 –2.0 µA tON(MIN) Minimum On Time (Note 4) 50 100 ns The ● denotes the specifi cations which apply over the –40°C to 85°C temperature range, otherwise specifi cations are at TA = 25°C, VIN = 12V. Per typical application (front page) confi guration.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS tOFF(MIN) Minimum Off Time (Note 4) 250 400 ns RPLLIN PLLIN Input Resistance 50 k Ω IDRVCC Current into DRVCC Pin V OUT = 1.5V, IOUT = 1A, Frequency = 850kHz, DRVCC = 5V 18 25 mA RFBHI Resistor Between VOUT and VFB 60.098 60.4 60.702 k Ω VMPGM Margin Reference Voltage 1.18 V VMARG0, VMARG1 MARG0, MARG1 Voltage Thresholds 1.4 V PGOOD Output ΔV FBH PGOOD Upper Threshold V FB Rising 7 10 13 % ΔVFBL PGOOD Lower Threshold V FB Falling –7 –10 –13 % ΔVFB(HYS) PGOOD Hysteresis V FB Returning 1.5 % The ● denotes the specifi cations which apply over the –40°C to 85°C temperature range, otherwise specifi cations are at TA = 25°C, VIN = 12V. Per typical application (front page) confi guration. 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 LTM4601HVE is guaranteed to meet performance specifi cations from 0°C to 85°C. Specifi cations over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. The LTM4601HVI is guaranteed and tested over the –40°C to 85°C temperature range. Note 3: Remote sense amplifi er recommended for ≤3.3V output. Note 4: 100% tested at wafer level only.
Effi ciency vs Load Current with 5VIN TYPICAL PERFOR A CE CHARACTERISTICSUW Effi ciency vs Load Current with 12VIN Effi ciency vs Load Current with 24V IN 1.2V Transient Response 1.5V Transient Response 2.5V Transient Response 3.3V Transient Res ponse (See Figures 19 and 20 for all curves) LOAD CURRENT (A) EFFICIENCY (%)75 4601HV G01 51 0 100 0.6VOUT 1.2VOUT 1.5VOUT 2.5VOUT 3.3VOUT LOAD CURRENT (A) EFFICIENCY (%) 100 5 10 4601HV G02 0.6VOUT 1.2VOUT 1.5VOUT 2.5VOUT 3.3VOUT 5VOUT LOAD CURRENT (A) EFFICIENCY (%) 5 10 4601HV G03 1.5VOUT 2.5VOUT 3.3VOUT 5.0VOUT VOUT 50mV/DIV 20µ s/DIV 4601HV G04 IOUT 5A/DIV 1.2V AT 6A/µ s LOAD STEP COUT = 3 22µ F 6.3V CERAMICS 470µ F 4V SANYO POSCAP C3 = 100pF VOUT 50mV/DIV 20µ s/DIV 4601HV G05 IOUT 5A/DIV 1.5V AT 6A/µ s LOAD STEP COUT = 3 22µ F 6.3V CERAMICS 470µ F 4V SANYO POSCAP C3 = 100pF 1.8V Transient Response VOUT 50mV/DIV 20µs/DIV 4601HV G06 IOUT 5A/DIV 1.8V AT 6A/µs LOAD STEP COUT = 3 22µF 6.3V CERAMICS 470µF 4V SANYO POSCAP C3 = 100pF VOUT 50mV/DIV 20µs/DIV 4601HV G07 IOUT 5A/DIV 2.5V AT 6A/µs LOAD STEP COUT = 3 22µF 6.3V CERAMICS 470µF 4V SANYO POSCAP C3 = 100pF VOUT 50mV/DIV 20µs/DIV 4601 G08 IOUT 5A/DIV 3.3V AT 6A/µs LOAD STEP COUT = 3 22µF 6.3V CERAMICS 470µF 4V SANYO POSCAP C3 = 100pF
TYPICAL PERFOR A CE CHARACTERISTICSUW (See Figures 19 and 20 for all curves) Start-Up, IOUT = 12A (Resistive Load) VOUT 0.5V/DIV 2ms/DIV 4601HV G10 IIN 1A/DIV VIN = 12V VOUT = 1.5V COUT = 470µF 3 × 22µF SOFT-START = 10nF INPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 3.0 4.0 5.5 5.0 4601HV G11 2.0 1.0 2.5 3.5 4.5 1.5 0.5 42 86 12 14 1810 20 22 24 3.3V OUTPUT WITH 130k FROM VOUT TO ION 5V OUTPUT WITH 100k RESISTOR ADDED FROM fSET TO GND 5V OUTPUT WITH NO RESISTOR ADDED FROM fSET TO GND 2.5V OUTPUT 1.8V OUTPUT 1.5V OUTPUT 1.2V OUTPUT Start-Up, IOUT = 0A VOUT 0.5V/DIV 5ms/DIV 4601HV G09 IIN 0.5A/DIV VIN = 12V VOUT = 1.5V COUT = 470µF 3 × 22µF SOFT-START = 10nF VIN to VOUT Step-Down Ratio Short-Circuit Protection, IOUT = 0A VOUT 0.5V/DIV 50µs/DIV 4601HV G13 IIN 1A/DIV VIN = 12V VOUT = 1.5V COUT = 470µF 3 × 22µF SOFT-START = 10nF Short-Circuit Protection, IOUT = 12A VOUT 0.5V/DIV 50µs/DIV 4601HV G14 IIN 1A/DIV VIN = 12V VOUT = 1.5V COUT = 470µF 3 × 22µF SOFT-START = 10nF Track, IOUT = 12A VFB 0.5V/DIV TRACK/SS 0.5V/DIV 2ms/DIV 4601HV G12 VOUT 1V/DIV VIN = 12V VOUT = 1.5V COUT = 470µF 3 × 22µF SOFT-START = 10nF
(See Package Description for Pin Assignment) VIN (Bank 1): Power Input Pins. Apply input voltage be- tween these pins and PGND pins. Recommend placing input decoupling capacitance directly between V IN pins and PGND pins. VOUT (Bank 3): Power Output Pins. Apply output load between these pins and PGND pins. Recommend placing output decoupling capacitance directly between these pins and PGND pins. Review the fi gure below. PGND (Bank 2): Power ground pins for both input and output returns. V OSNS– (Pin M12): (–) Input to the Remote Sense Amplifi er. This pin connects to the ground remote sense point. The remote sense amplifi er is used for V OUT ≤3.3V. VOSNS+ (Pin J12): (+) Input to the Remote Sense Amplifi er. This pin connects to the output remote sense point. The remote sense amplifi er is used for V OUT ≤3.3V. DIFFVOUT (Pin K12): Output of the Remote Sense Ampli- fi er. This pin connects to the VOUT_LCL pin. DRVCC (Pin E12): This pin normally connects to INTVCC for powering the internal MOSFET drivers. This pin can be biased up to 6V from an external supply with about 50mA capability, or an external circuit shown in Figure 18. This improves effi ciency at the higher input voltages by reducing power dissipation in the module. INTV CC (Pin A7): This pin is for additional decoupling of the 5V internal regulator. PLLIN (Pin A8): External Clock Synchronization Input to the Phase Detector. This pin is internally terminated to SGND with a 50k resistor. Apply a clock above 2V and below INTV CC. See Applications Information. TRACK/SS (Pin A9): Output Voltage Tracking and Soft- Start Pin. When the module is confi gured as a master output, then a soft-start capacitor is placed on this pin to ground to control the master ramp rate. A soft-start capacitor can be used for soft-start turn on as a stand alone regulator. Slave operation is performed by putting a resistor divider from the master output to the ground, and connecting the center point of the divider to this pin. See Applications Information. MPGM (Pin A12): Programmable Margining Input. A re- sistor from this pin to ground sets a current that is equal to 1.18V/R. This current multiplied by 10k Ω will equal a value in millivolts that is a percentage of the 0.6V refer- ence voltage. See Applications Information. To parallel LTM4601HVs, each requires an individual MPGM resistor. Do not tie MPGM pins together. f SET (Pin B12): Frequency Set Internally to 850kHz. An external resistor can be placed from this pin to ground to increase frequency. This pin can be decoupled with a 1000pF capacitor. See Applications Information for fre- quency adjustment. V FB (Pin F12): The Negative Input of the Error Amplifi er. Internally, this pin is connected to V OUT_LCL pin with a 60.4k precision resistor. Different output voltages can be programmed with an additional resistor between V FB and SGND pins. See Applications Information. MARG1 DRVCC VFB PGOOD SGND V OSNS+ DIFFVOUT VOUT_LCL VOSNS– VIN BANK 1 PGND BANK 2 A B C D E F G H J K L M V OUT BANK 3 fSET MARG0 RUN COMP MPGM PLLIN INTVCC TRACK/SS 1234567 TOP VIEW 8 9 10 11 12
Figure 1. Simplifi ed LTM4601HV Block Diagram 50k. See Applications Information. 50k. See Applications Information. PGND at output capacitor point. sense voltage (zero current). PGOOD (Pin G12): Output Voltage Power Good Indicator. after a 25µs power bad mask timer expires. has a 5.1V zener to ground. Maximum pin voltage is 5V. Limit current into the RUN pin to less than 1mA. to this pin when remote sense amplifi er is used.
W UDECOUPLI G REQUIRE E TSU SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS CIN External Input Capacitor Requirement (VIN = 4.5V to 28V, VOUT = 2.5V) IOUT = 12A, 3× 10µF Ceramics 20 30 µF COUT External Output Capacitor Requirement (VIN = 4.5V to 28V, VOUT = 2.5V) IOUT = 12A 100 200 µF T A = 25°C, VIN = 12V. Use Figure 1 confi guration. OPERATIOU Power Module Description The LTM4601HV is a standalone nonisolated switching mode DC/DC power supply. It can deliver up to 12A of DC output current with some external input and output capacitors. This module provides precisely regulated output voltage programmable via one external resistor from 0.6V DC to 5.0V DC over a 4.5V to 28V wide input voltage. The typical application schematics are shown in Figures 19 and 20. The LTM4601HV has an integrated constant on-time current mode regulator, ultralow R DS(ON) FETs with fast switching speed and integrated Schottky diodes. The typical switching frequency is 850kHz at full load. With current mode control and internal feedback loop compensation, the LTM4601HV module has suffi cient stability margins and good transient performance under a wide range of operating conditions and with a wide range of output capacitors, even all ceramic output capacitors. Current mode control provides cycle-by-cycle fast current limit. Besides, foldback current limiting is provided in an overcurrent condition while V FB drops. Internal overvoltage and undervoltage comparators pull the open-drain PGOOD output low if the output feedback voltage exits a ±10% window around the regulation point. Furthermore, in an overvoltage condition, internal top FET Q1 is turned off and bottom FET Q2 is turned on and held on until the overvoltage condition clears. Pulling the RUN pin below 1V forces the controller into its shutdown state, turning off both Q1 and Q2. At low load current, the module works in continuous current mode by default to achieve minimum output voltage ripple. When DRV CC pin is connected to INTV CC an integrated 5V linear regulator powers the internal gate drivers. If a 5V external bias supply is applied on the DRV CC pin, then an effi ciency improvement will occur due to the reduced power loss in the internal linear regulator. This is especially true at the higher input voltage range. The LTM4601HV has a very accurate differential remote sense amplifi er with very low offset. This provides for very accurate remote sense voltage measurement. The MPGM pin, MARG0 pin and MARG1 pin are used to sup- port voltage margining, where the percentage of margin is programmed by the MPGM pin, and the MARG0 and MARG1 select margining. The PLLIN pin provides frequency synchronization of the device to an external clock. The TRACK/SS pin is used for power supply tracking and soft-start programming.
requirements for a particular application. down ratio that can be achieved for a given input voltage. The PWM controller has an internal 0.6V reference voltage. Table 1. Standard 1% Resistor Values RPGM resistor on the MPGM pin programs the current. The output margining will be ± margining of the value. by long inductive leads or traces.
current for the external input capacitors. The LTM4601HV is designed for low output voltage ripple. to maximize transient performance. Figure 2. Normalized Input RMS Ripple Current
The RUN pin is used to enable the power module. The pin has an internal 5.1V zener to ground. The pin can be driven with a logic input not to exceed 5V. The RUN pin can also be used as an undervoltage lock out (UVLO) function by connecting a resistor divider from the input supply to the RUN pin: V RR R VUVLO = +12 2 15. Power Good The PGOOD pin is an open-drain pin that can be used to monitor valid output voltage regulation. This pin monitors a ±10% window around the regulation point and tracks with margining. COMP Pin This pin is the external compensation pin. The module has already been internally compensated for most output voltages. Table 2 is provided for most application require- ments. A spice model will be provided for other control loop optimization. PLLIN The power module has a phase-locked loop comprised of an internal voltage controlled oscillator and a phase detector. This allows the internal top MOSFET turn-on to be locked to the rising edge of the external clock. The frequency range is ±30% around the operating frequency of 850kHz. A pulse detection circuit is used to detect a clock on the PLLIN pin to turn on the phase lock loop. The pulse width of the clock has to be at least 400ns and 2V in amplitude. During the start-up of the regulator, the phase-lock loop function is disabled. INTV CC and DRVCC Connection An internal low dropout regulator produces an internal 5V supply that powers the control circuitry and DRV CC for driving the internal power MOSFETs. Therefore, if the system does not have a 5V power rail, the LTM4601HV can be directly powered by V IN. The gate driver current through the LDO is about 20mA. The internal LDO power dissipation can be calculated as: P LDO_LOSS = 20mA • (VIN – 5V) The LTM4601HV also provides the external gate driver voltage pin DRVCC. If there is a 5V rail in the system, it is recommended to connect DRV CC pin to the external 5V rail. This is especially true for higher input voltages. Do not apply more than 6V to the DRV CC pin. A 5V output can be used to power the DRV CC pin with an external circuit as shown in Figure 18. Parallel Operation of the Module The LTM4601HV device is an inherently current mode controlled device. Parallel modules will have very good current sharing. This will balance the thermals on the de- sign. Figure 21 shows a schematic of the parallel design. The voltage feedback equation changes with the variable n as modules are paralleled: VV k n R ROUT FB FB 60 4 n is the number of paralleled modules. Figure 21 shows two LTM4601HV modules used in a par- allel design. An LTM4601HV device can be used without the diff amp. Thermal Considerations and Output Current Derating The power loss curves in Figures 7 and 8 can be used in coordination with the load current derating curves in Figures 9 to 16 for calculating an approximate θ JA for the module with various heat sinking methods. Thermal models are derived from several temperature measurements at the bench and thermal modeling analysis. Thermal Ap- plication Note 103 provides a detailed explanation of the analysis for the thermal models and the derating curves. Tables 3 and 4 provide a summary of the equivalent θ JA for the noted conditions. These equivalent θJA parameters are correlated to the measured values, and are improved with air fl ow. The case temperature is maintained at 100°C or below for the derating curves. The maximum case temperature of 100°C is to allow for a rise of about 13°C APPLICATIO S I FOR ATIOWU UU
Table 2. Output Voltage Response Versus Component Matrix (Refer to Figure 20), 0A to 6A Load Step
APPLICATIO S I FOR ATIOWU UU Frequency Adjustment The LTM4601HV is designed to typically operate at 850kHz across most input conditions. The fSET pin is normally left open or decoupled with an optional 1000pF capacitor. The switching frequency has been optimized for maintaining constant output ripple noise over most operating ranges. The 850kHz switching frequency and the 400ns minimum off time can limit operation at higher duty cycles like 5V to 3.3V, and produce excessive inductor ripple currents for lower duty cycle applications like 28V to 5V. The 5V and 3.3V drop out curves are modifi ed by adding an external resistor on the f SET pin to allow for lower input voltage operation, or higher input voltage operation. Example for 5V Output LTM4601HV minimum on-time = 100ns; t ON = ((4.8 • 10pf)/IfSET) LTM4601HV minimum off-time = 400ns; t OFF = t – tON, where t = 1/Frequency Duty Cycle = t ON/t or VOUT/VIN Equations for setting frequency: I fSET = (VIN/(3 • RfSET)), for 28V operation, ISET = 238µA, tON = ((4.8 • 10pF)/IfSET), tON = 202ns, where the internal RfSET is 39.2k. Frequency = (VOUT/(VIN • tON)) = (5V/(28 • 202ns)) ~ 884kHz. The inductor ripple current begins to get high at the higher input voltages due to a larger voltage across the inductor. This is noted in the Typical Inductor Ripple Current verses Duty Cycle graph (Figure 3) where I L ≈ 10A at 20% duty cycle. The inductor ripple current can be lowered at the higher input voltages by adding an external resistor from f SET to ground to increase the switch- ing frequency. A 7A ripple current is chosen, and the total peak current is equal to 1/2 of the 7A ripple current plus the output current. The 5V output current is limited to 8A, so the total peak current is less than 11.5A. This is below the 14A peak specifi ed value. A 100k resistor is placed from f SET to ground, and the parallel combination of 100k and 39.2k equates to 28k. The IfSET calculation with 28k and 28V input voltage equals 333µA. This equates to a tON of 144ns. This will increase the switching frequency from ~884kHz to ~1.24MHz for the 28V to 5V conversion. The minimum on time is above 100ns at 28V input. Since the switching frequency is approximately constant over input and output conditions, then the lower input voltage range is limited to 10V for the 1.24MHz operation due to the 400ns minimum off time. Equation: t ON = (VOUT/VIN)
- (1/Frequency) equates to a 400ns on time, and a 400ns off time. The “V IN to VOUT Step Ratio Curve” refl ects an operating range of 10V to 28V for 1.24MHz operation with a 100k resistor to ground as shown in Figure 18, and an 8V to 16V operation for f SET fl oating. These modifi cations are made to provide wider input voltage ranges for the 5V output designs while limiting the inductor ripple current, and maintaining the 400ns minimum off time. Example for 3.3V Output LTM4601HV minimum on-time = 100ns; t ON = ((3.3 • 10pF)/IfSET) LTM4601HV minimum off-time = 400ns; t OFF = t – tON, where t = 1/Frequency Duty Cycle (DC) = t ON/t or VOUT/VIN Equations for setting frequency: I fSET = (VIN/(3 • RfSET)), for 28V operation, IfSET = 238µA, tON = ((3.3 • 10pf)/IfSET), tON = 138.7ns, where the internal RfSET is 39.2k. Frequency = (VOUT/(VIN • tON)) = (3.3V/(28 • 138.7ns)) ~ 850kHz. The minimum on-time and minimum- off time are within specifi cation at 139ns and 1037ns. The 4.5V minimum input for converting 3.3V output will not meet the minimum off-time specifi cation of 400ns. t ON = 868ns, Frequency = 850kHz, tOFF = 315ns.
Figure 18. 5V at 8A Design Without Differential Amplifi er into the f SET node and lower the I fSET current to 24µA.
Figure 21. 2-Phase Parallel, 3.3V at 20A Design *C5 OPTIONAL TO REDUCE ANY LC RINGING.
118-Lead (15mm × 15mm) (Reference LTM DWG # 05-05-1801, Rev Ø) PACKAGE DESCRIPTIO U NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994 2. ALL DIMENSIONS ARE IN MILLIMETERS LAND DESIGNATION PER JESD MO-222, SPP-010 5. PRIMARY DATUM -Z- IS SEATING PLANE 6. THE TOTAL NUMBER OF PADS: 118 DETAILS OF PAD #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE PAD #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE SYMBOL aaa bbb eee TOLERANCE 0.10 0.10 0.03 2.72 – 2.92 DETAIL BDETAIL A DETAIL B SUBSTRATE MOLD CAP 0.27 – 0.37 2.45 – 2.55 bbb Z Z BSC TOP VIEW BSC PAD 1 CORNER X Y aaa Z aaa Z 13.97 BSC 1.27 BSC 13.97 BSC 0.12 – 0.28 23 45 678 9 1 0 1 1 BOTTOM VIEW C(0.30) PAD 1 PADS SEE NOTES1 SUGGESTED SOLDER PAD LAYOUT TOP VIEW A B C D E F G H K J L M DETAIL A 0.60 – 0.66 0.60 – 0.66 M YXeee 0.0000 0.6350 0.6350 1.9050 1.9050 3.1750 3.1750 4.4450 4.4450 5.7150 5.7150 6.9850 6.9850 6.9850 5.7150 5.7150 4.4450 4.4450 3.1750 3.1750 1.9050 1.9050 0.6350 0.6350 0.0000 6.9850 LGA 118 0306 REV Ø
PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME A1 V IN B1 V IN C1 V IN D1 PGND E1 PGND F1 PGND A2 V IN B2 V IN C2 V IN D2 PGND E2 PGND F2 PGND A3 V IN B3 V IN C3 V IN D3 PGND E3 PGND F3 PGND A4 V IN B4 V IN C4 V IN D4 PGND E4 PGND F4 PGND A5 V IN B5 V IN C5 V IN D5 PGND E5 PGND F5 PGND A6 V IN B6 V IN C6 V IN D6 PGND E6 PGND F6 PGND A7 INTV CC B7 - C7 - D7 - E7 PGND F7 PGND A8 PLLIN B8 - C8 - D8 - E8 - F8 PGND A9 TRACK/SS B9 - C9 - D9 - E9 - F9 PGND A10 RUN B10 - C10 - D10 - E10 - F10 - A11 COMP B11 - C11 - D11 - E11 - F11 - A12 MPGM B12 f SET C12 MARG0 D12 MARG1 E12 DRV CC F12 V FB PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME G1 PGND H1 PGND J1 V OUT K1 V OUT L1 V OUT M1 V OUT G2 PGND H2 PGND J2 V OUT K2 V OUT L2 V OUT M2 V OUT G3 PGND H3 PGND J3 V OUT K3 V OUT L3 V OUT M3 V OUT G4 PGND H4 PGND J4 V OUT K4 V OUT L4 V OUT M4 V OUT G5 PGND H5 PGND J5 V OUT K5 V OUT L5 V OUT M5 V OUT G6 PGND H6 PGND J6 V OUT K6 V OUT L6 V OUT M6 V OUT G7 PGND H7 PGND J7 V OUT K7 V OUT L7 V OUT M7 V OUT G8 PGND H8 PGND J8 V OUT K8 V OUT L8 V OUT M8 V OUT G9 PGND H9 PGND J9 V OUT K9 V OUT L9 V OUT M9 V OUT G10 - H10 - J10 V OUT K10 V OUT L10 V OUT M10 V OUT G11 - H11 - J11 - K11 V OUT L11 V OUT M11 V OUT G12 PGOOD H12 SGND J12 V OSNS+ K12 DIFFV OUT L12 V OUT_LCL M12 V OSNS– Pin Assignment Tables (Arranged by Pin Number)
V IN VIN VIN VIN VIN VIN V IN VIN VIN VIN VIN VIN V IN VIN VIN VIN VIN VIN Pin Assignment Tables (Arranged by Pin Function) PIN NAME PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PIN NAME J10 V OUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT K10 K11 V OUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT L10 L11 V OUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT M10 M11 V OUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT PIN NAME A10 A11 A12 INTVCC PLLIN TRACK/SS RUN COMP MPGM B12 f SET C12 MARG0 D12 MARG1 E12 DRV CC F12 V FB G12 PGOOD H12 SGND J12 V OSNS+ K12 DIFFV OUT L12 V OUT_LCL M12 V OSNS– PIN NAME B10 B11 C10 C11 D10 D11 E10 E11 F10 F11 G10 G11 H10 H11 J11 - Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
© LINEAR TECHNOLOGY CORPORATION 2007 LT 0307 • PRINTED IN USA Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC2900 Quad Supply Monitor with Adjustable Reset Timer Monitors Four Supplies; Adjustable Reset Timer LTC2923 Power Supply Tracking Controller Tracks Both Up and Down; Power Supply Sequencing LT3825/LT3837 Synchronous Isolated Flyback Controllers No Optocoupler Required; 3.3V, 12A Output; Simple Design LTM4600 10A DC/DC µModule Fast Transient Response LTM46O2 6A DC/DC µModule Pin Compatible with the LTM4600 LTM4603 6A DC/DC µModule with Tracking PLL/Margining Pin Compatible with the LTM4601 This product contains technology licensed from Silicon Semiconductor Corporation.