LTM4601

LTM4601 LINER | Alldatasheet

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12A DC/DC µModules 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 20V ■ 12A DC Typical, 14A Peak Output Current ■ 0.6V to 5V Output Voltage ■ Output Voltage Tracking and Margining ■ Parallel Multiple µModules for Current Sharing ■ Differential Remote Sensing for Precision Regulation (LTM4601 Only) ■ 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 1.5V/12A Power Supply with 4.5V to 20V Input APPLICATIO SU FEATURES DESCRIPTIO U TYPICAL APPLICATIO U Effi ciency and Power Loss vs Load Current The LTM®4601 is a complete 12A step-down switch mode DC/DC power supply with onboard switching controller, MOSFETs, inductor and all support components. The µModule TM is housed in a small surface mount 15mm ×15mm × 2.8mm LGA package. Operating over an input voltage range of 4.5 to 20V, the LTM4601 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) pack- age 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. The onboard remote sense amplifi er is not available in the LTM4601-1. , LTC, LT 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, 6677210VOUT VFB MARG0 MARG1 VOUT_LCL DIFFVOUT VOSNS+ VOSNS– PGOOD RUN COMP INTV CC DRVCC MPGM TRACK/SSPLLIN LTM4601 ON/OFF 392k RSET 40.2k MARGIN CONTROL COUT

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1.5V 12A CLOCK SYNC TRACK/SS CONTROL 100pF CIN VIN fSETPGNDSGND 5% MARGIN VIN 4.5V TO 20V OUTPUT CURRENT (A) EFFICIENCY (%) POWER LOSS (W)

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0.5 1.0 2.0 4.0 1.5 2.5 3.0 3.5 12VIN 12VIN 5VIN 5VIN EFFICIENCY POWER LOSS

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 20 V VOUT(DC) Output Voltage C IN = 10µF ×3, COUT = 200µF V IN = 5V, VOUT = 1.5V, IOUT = 0A V IN = 12V, VOUT = 1.5V, IOUT = 0A 1.478 1.478 1.5 1.5 1.522 1.522 V 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,NOLOAD) 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 MARG1 DRVCC VFB PGOOD SGND V OSNS+/NC2* DIFFVOUT/NC3* VOUT_LCL VOSNS–/NC1* 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 *LTM4601-1 ONLY ORDER PART NUMBER LGA PART MARKING* LTM4601EV#PBF LTM4601IV#PBF LTM4601EV-1#PBF LTM4601IV-1#PBF LTM4601V LTM4601V LTM4601V-1 LTM4601V-1 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 INTVCC VIN = 12V, RUN > 2V No Load 4.7 5 5.3 V 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(MIN) Line Regulation Accuracy V OUT = 1.5V, IOUT = 0A, VIN from 4.5V to 20V ● 0.3 % ΔVOUT(0A-12A) VOUT(MIN) Load Regulation Accuracy V OUT = 1.5V, 0A to 12A V IN = 12V, Remote Sense Amplifi er V IN = 12V (LTM4601-1) 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) (LTM4601 Only, Not Supported in the LTM4601-1) 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 LTM4601E/LTM4601E-1 are 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 LTM4601I/LTM4601I-1 are 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 20V IN 1.2V Transient Response 1.5V Transient Response 2.5V Transient Response 3.3V Transient Res ponse (See Figure 18 for all curves) OUTPUT CURRENT (A) EFFICIENCY (%)75

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0.6VOUT 1.2VOUT 1.5VOUT 2.5VOUT 3.3VOUT OUTPUT CURRENT (A) EFFICIENCY (%) 100 5 10

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0.6VOUT 1.2VOUT 1.5VOUT 2.5VOUT 3.3VOUT 5VOUT OUTPUT CURRENT (A) 100

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EFFICIENCY (%) 1.2VOUT 1.5VOUT 2.5VOUT 3.3VOUT 5.0VOUT VOUT 50mV/DIV 20µ s/DIV 4601 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 4601 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 20µ s/DIV 4601 G06 IOUT 5A/DIV 1.8V 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 4601 G07 IOUT 5A/DIV 2.5V 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 4601 G08 IOUT 5A/DIV 3.3V AT 6A/µ s LOAD STEP COUT = 3  22µ F 6.3V CERAMICS 470µ F 4V SANYO POSCAP C3 = 100pF

TYPICAL PERFOR A CE CHARACTERISTICSUW (See Figure 18 for all curves) Start-Up, IOUT = 12A (Resistive Load) VOUT 0.5V/DIV 2ms/DIV 4601 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

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2.0 1.0 2.5 3.5 4.5 1.5 0.5 42 86 12 14 1810 20 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 4601 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 4601 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 4601 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 4601 G12 VOUT 1V/DIV VIN = 12V VOUT = 1.5V COUT = 470/K6D F 3 /KB4 22/K6D F 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. NC1 (Pin M12): No Connect On the LTM4601-1. 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. NC2 (Pin J12): No Connect On the LTM4601-1. DIFFVOUT (Pin K12): Output of the Remote Sense Ampli- fi er. This pin connects to the VOUT_LCL pin. NC3 (Pin K12): No Connect On the LTM4601-1. 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 16. 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 LTM4601s, 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+/NC2* DIFFVOUT/NC3* VOUT_LCL VOSNS–/NC1* 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 *LTM4601-1 ONLY TOP VIEW 8 9 10 11 12

Figure 1. Simplifi ed LTM4601/LTM4601-1 Block Diagram

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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. current into the RUN pin to less than 1mA. nects 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 20V, VOUT = 1.5V) IOUT = 12A, 3× 10µF Ceramics 20 30 µF COUT External Output Capacitor Requirement (VIN = 4.5V to 20V, VOUT = 1.5V) IOUT = 12A 100 200 µF T A = 25°C, VIN = 12V. Use Figure 1 confi guration. OPERATIOU Power Module Description The LTM4601 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 5.0VDC over a 4.5V to 20V wide input voltage. The typical application schematic is shown in Figure 18. The LTM4601 has an integrated constant on-time current mode regulator, ultralow RDS(ON) FETs with fast switch- ing speed and integrated Schottky diodes. The typical switching frequency is 850kHz at full load. With current mode control and internal feedback loop compensation, the LTM4601 module has suffi cient stability margins and good transient performance under a wide range of operat- ing 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 LTM4601 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.

Figure 18. External component selection is primarily 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. long inductive leads or traces.

current for the external input capacitors. The LTM4601 is designed for low output voltage ripple. to maximize transient performance. Figure 2. Normalized Input RMS Ripple Current

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duty cycle is ~6A in Figure 3. current reduction as a function of paralleled phases. series resistance (ESR) of the output bulk capacitance. Figure 4. Normalized Output Ripple Current vs Duty Cycle, Dlr = VOT/LI, Dlr = Each Phase’s Inductor Current

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Figure 3. Inductor Ripple Current vs Duty Cycle

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APPLICATIO S I FOR ATIOWU UU is frequency and m is the number of parallel phases. This calculation process can be easily fulfi lled using our Linear Technology µModule Design Tool. Fault Conditions: Current Limit and Overcurrent Foldback LTM4601 has a current mode controller, which inher- ently limits the cycle-by-cycle inductor current not only in steady-state operation, but also in transient. To further limit current in the event of an overload condi- tion, the LTM4601 provides foldback current limiting. If the output voltage falls by more than 50%, then the maximum output current is progressively lowered to about one sixth of its full current limit value. Soft-Start and Tracking The TRACK/SS pin provides a means to either soft-start the regulator or track it to a different power supply. A capacitor on this pin will program the ramp rate of the output voltage. A 1.5µA current source will charge up the external soft-start capacitor to 80% of the 0.6V internal voltage reference minus any margin delta. This will control the ramp of the internal reference and the output voltage. The total soft-start time can be calculated as: tV V V C µSOFTSTART OUT MARGIN When the RUN pin falls below 1.5V, then the SS pin is reset to allow for proper soft-start control when the regulator is enabled again. Current foldback and force continuous mode are disabled during the soft-start process. The soft-start function can also be used to control the output ramp up time, so that another regulator can be easily tracked to it. Output Voltage Tracking Output voltage tracking can be programmed externally using the TRACK/SS pin. The output can be tracked up and down with another regulator. The master regulator’s output is divided down with an external resistor divider that is the same as the slave regulator’s feedback divider. Figure 5 shows an example of coincident tracking. Ratiometric modes of tracking can be achieved by selecting different resistor values to change the output tracking ratio. The master output must be greater than the slave output for the tracking to work. Figure 6 shows the coincident output tracking characteristics. Figure 5 Figure 6 VOUT VFB MARG0 MARG1 VOUT_LCL DIFFVOUT VOSNS+ VOSNS– PGOOD MPGM RUN COMP INTV CC DRVCC TRACK/SS TRACK CONTROL PLLIN LTM4601 RSET 40.2k 100k 40.2k MASTER OUTPUT 60.4k C OUT SLAVE OUTPUT

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60.4k FROM VOUT TO VFB CIN VIN fSETPGNDSGND VIN OUTPUT VOLTAGE TIME

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Figure 7. 1.5V Power Loss Figure 8. 3.3V Power Loss Figure 9. No Heat Sink 5VIN

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Figure 10. BGA Heat Sink 5VIN

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Figure 11. No Heat Sink 12VIN Figure 12. BGA Heat Sink 12VIN Figure 13. 12VIN, 3.3VOUT, No Heat Sink

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Figure 14. 12VIN, 3.3VOUT, BGA Heat Sink

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Table 2. Output Voltage Response Versus Component Matrix (Refer to Figure 18), 0A to 6A Load Step

• Use large PCB copper areas for high current path, in- cluding V IN, PGND and VOUT. It helps to minimize the PCB conduction loss and thermal stress.
• Place high frequency ceramic input and output capaci- tors next to the VIN, PGND and VOUT pins to minimize high frequency noise.
• Place a dedicated power ground layer underneath the unit. Refer frequency synchronization source to power ground.
• To minimize the via conduction loss and reduce module thermal stress, use multiple vias for interconnection between top layer and other power layers.
• Do not put vias directly on pads.
• Use a separated SGND ground copper area for com- ponents connected to signal pins. Connect the SGND to PGND underneath the unit. Figure 15 gives a good example of the recommended layout. SIGNAL GND VOUT VIN GND COUT CIN CIN COUT

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Figure 15. Recommended Layout

APPLICATIO S I FOR ATIOWU UU Frequency Adjustment The LTM4601 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 20V 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 LTM4601 minimum on-time = 100ns; t ON = ((4.8 • 10pf)/IfSET) LTM4601 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 20V operation, ISET = 170µA, tON = ((4.8 • 10pF)/IfSET), tON = 282ns, where the internal RfSET is 39.2k. Frequency = (VOUT/(VIN • tON)) = (5V/(20 • 282ns)) ~ 886kHz. 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 25% 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. An 8A ripple current is chosen, and the total peak current is equal to 1/2 of the 8A ripple current plus the output current. The 5V output current is limited to 8A, so the total peak current is less than 12A. 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 20V input voltage equals 238µA. This equates to a tON of 200ns. This will increase the switching frequency from ~886kHz to ~1.25MHz for the 20V to 5V conversion. The minimum on time is above 100ns at 20V 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 1.25MHz 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 20V for 1.25MHz operation with a 100k resistor to ground, 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 LTM4601 minimum on-time = 100ns; t ON = ((3.3 • 10pF)/IfSET) LTM4601 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 20V operation, IfSET = 170µA, tON = ((3.3 • 10pf)/IfSET), tON = 195ns, where the internal RfSET is 39.2k. Frequency = (VOUT/(VIN • tON)) = (3.3V/(20
• 195ns)) ~ 846kHz. The minimum on-time and minimum- off time are within specifi cation at 195ns and 980ns. 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 16. 5V at 8A Design Without Differential Amplifi er the IfSET current equates to 38µA with the internal 39.2k. The IfSET current needs to be 24µA for 540kHz operation. output current of 8A over the input range.

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Figure 17. 3.3V at 10A Design Figure 18. Typical 4.5V-20VIN, 1.5V at 12A Design

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Figure 19. 2-Phase Parallel, 1.5V at 24A Design

4601 F19

*C5 OPTIONAL TO REDUCE ANY LC RINGING.

VOUT_LCL DIFFVOUT VOSNS+ VOSNS– PGOOD MPGM RUN COMP INTV CC DRVCC TRACK/SSPLLIN LTM4601 392k R11 100k R10 100k R18 19.1k C16 22µF 6.3V C14 10µF 25V 3.3V 2.5V AT 12A R23 60.4k C15 470µF 6.3VMARGIN CONTROL CLOCK SYNC 2 C18 100pF REFER TO TABLE 2 V IN fSETPGNDSGND 5% MARGIN +PGOOD 8V TO 16V ON/OFF VOUT VFB MARG0 MARG1 VOUT_LCL DIFFVOUT VOSNS+ VOSNS– PGOOD MPGM RUN COMP INTV CC DRVCC TRACK/SSPLLIN LTM4601 R14 392k R16 100k R15 100k R13 40.2k C16 22µF 6.3V C14 10µF 25V 3.3V R25 60.4k C15 470µF 6.3VMARGIN CONTROL 1.5V AT 12A CLOCK SYNC 4 C24 100pF REFER TO TABLE 2 V IN fSETPGNDSGND 5% MARGIN +PGOOD 8V TO 16V ON/OFF VOUT VFB MARG0 MARG1 VOUT_LCL DIFFVOUT VOSNS+ VOSNS– PGOOD MPGM RUN COMP INTV CC DRVCC TRACK/SSPLLIN LTM4601 392k 100k 100k R12 30.1k 22µF 6.3V 10µF 25V 3.3V R21 60.4k R19 30.1k 470µF 6.3VMARGIN CONTROL 1.8V AT 12A CLOCK SYNC 3 TRACK 2.5V C8 100pF REFER TO TABLE 2 V IN fSETPGNDSGND 5% MARGIN +PGOOD 8V TO 16V ON/OFF R17 59k C26 0.1µF LTC6902 4-PHASE OSCILLATOR 3.3V AT 10A DIV PH OUT1 OUT2 SET MOD GND OUT4 OUT3 VOUT VFB MARG0 MARG1 VOUT_LCL DIFFVOUT VOSNS+ VOSNS– PGOOD MPGM RUN COMP INTV CC DRVCC TRACK/SSPLLIN LTM4601 R27 392k 100k 100k 13.3k 22µF 6.3V 0.15µF 10µF 25V C11 100µF 35V OPT C10 470µF 6.3VMARGIN CONTROL TRACK/SS CONTROL CLOCK SYNC 1 C12 100pF REFER TO TABLE 2 V IN 3.3V fSETPGNDSGND 5% MARGIN +PGOOD 8V TO 16V 8V TO 16V ON/OFF INTERMEDIATE BUS –48V INPUT R24 19.1k R26 40.2k 3.3V 3.3V 3.3V 4-Phase, Four Outputs (3.3V, 2.5V, 1.8V and 1.5V) with Tracking

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 0107 • 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 Basic 10A DC/DC µModule LTM4601 12A DC/DC µModule with PLL, Output Tracking/ Margining and Remote Sensing Synchronizable, PolyPhase Operation to 48A, LTM4601-1 Version has no Remote Sensing LTM4602 6A DC/DC µModule Pin Compatible with the LTM4600 LTM4603 6A DC/DC µModule with PLL and Outpupt Tracking/ Margining and Remote Sensing Synchronizable, PolyPhase Operation to 48A, LTM4601-1 Version has no Remote Sensing, Pin Compatible with the LTM4601 This product contains technology licensed from Silicon Semiconductor Corporation.