LTM4600HV 10A, 28VIN High Efficiency DC/DC µModule DESCRIPTIO U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Complete Switch Mode Power Supply Wide Input Voltage Range: 4.5V to 28V 10A DC, 12A Peak Output Current Parallel Two μModule™ DC/DC Converters for 20A Output Current 0.6V to 5V Output Voltage 1.5% Output Voltage Regulation Ultrafast Transient Response Current Mode Control –55°C to 125°C Operating Temperature Range (LTM4600HVMPV) Pb-Free (e4) RoHS Compliant Package Gold-Pad Finish Up to 92% Efficiency Programmable Soft-Start Output Overvoltage Protection Optional Short-Circuit Shutdown Timer Small Footprint, Low Profile (15mm × 15mm × 2.8mm) LGA Package U APPLICATIO S ■ ■ ■ ■ The low profile package (2.8mm) enables utilization of unused space on the bottom of PC boards for high density point of load regulation. High switching frequency and an adaptive on-time current mode architecture enables a very fast transient response to line and load changes without sacrificing stability. Fault protection features include integrated overvoltage and short circuit protection with a defeatable shutdown timer. A built-in soft-start timer is adjustable with a small capacitor. The LTM4600HV is packaged in a thermally enhanced, compact (15mm × 15mm) and low profile (2.8mm) overmolded Land Grid Array (LGA) package suitable for automated assembly by standard surface mount equipment. The LTM4600HV is Pb-free and RoHS compliant. Telecom and Networking Equipment Military and Avionics Systems Industrial Equipment Point of Load Regulation Servers , LTC, LT and LTM 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. U ■ The LTM®4600HV is a complete 10A, DC/DC step down power supply with up to 28V input operation. Included in the package are the switching controller, power FETs, inductor, and all support components. Operating over an input voltage range of 4.5V to 28V, the LTM4600HV supports an output voltage range of 0.6V to 5V, set by a single resistor. This high efficiency design delivers 10A continuous current (12A peak), needing no heat sinks or airflow to meet power specifications. Only bulk input and output capacitors are needed to finish the design. TYPICAL APPLICATIO Efficiency vs Load Current with 24VIN (FCB = 0) 100 10A μModule Power Supply with 4.5V to 28V Input VIN 4.5V TO 28V ABSMAX VIN CIN VOUT 2.5V* 10A VOUT LTM4600HV COUT VOSET PGND SGND 31.6k 4600hv TA01a *REVIEW DE-RATING CURVE AT THE HIGHER INPUT VOLTAGE 90 80 EFFICIENCY (%) ■ 70 60 50 1.8VOUT 2.5VOUT 3.3VOUT 5VOUT 40 30 0 2 4 6 LOAD CURRENT (A) 8 10 4600HV TA01b 4600hvfc 1 LTM4600HV U W W W ABSOLUTE AXI U RATI GS PIN CONFIGURATION (Note 1) fADJ SVIN EXTVCC VOSET TOP VIEW FCB, EXTVCC, PGOOD, RUN/SS, VOUT .......... –0.3V to 6V VIN, SVIN, fADJ ............................................ –0.3V to 28V VOSET, COMP ............................................. –0.3V to 2.7V Operating Temperature Range (Note 2) E and I Grades ..................................... –40°C to 85°C MP Grade........................................... –55°C to 125°C Junction Temperature ........................................... 125°C Storage Temperature Range................... –55°C to 125°C COMP SGND RUN/SS FCB VIN PGOOD PGND VOUT LGA PACKAGE 104-LEAD (15mm × 15mm × 2.8mm) TJMAX = 125°C, θJA = 15°C/W, θJC = 6°C/W, θJA DERIVED FROM 95mm × 76mm PCB WITH 4 LAYERS, WEIGHT = 1.7g ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTM4600HVEV#PBF LTM4600HVIV#PBF LTM4600HVMPV#PBF LTM4600HVEV#TRPBF LTM4600HVIV#TRPBF LTM4600HVMPV#TRPBF LTM4600HVEV LTM4600HVIV LTM4600HVMPV 104-Lead (15mm × 15mm × 2.8mm) 104-Lead (15mm × 15mm × 2.8mm) 104-Lead (15mm × 15mm × 2.8mm) –40°C to 85°C –40°C to 85°C –55°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. 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/ ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VIN = 12V. External CIN = 120μF, COUT = 200μF/Ceramic per typical application (front page) configuration. SYMBOL VIN(DC) PARAMETER Input DC Voltage CONDITIONS AbsMax 28V for Tolerance on 24V Inputs VOUT(DC) Output Voltage FCB = 0V VIN = 5V or 12V, VOUT = 1.5V, IOUT = 0A MIN 4.5 TYP ● MAX 28 ● 1.478 1.470 1.50 1.50 1.522 1.530 3.4 4 UNITS V V Input Specifications VIN(UVLO) Under Voltage Lockout Threshold IOUT = 0A IINRUSH(VIN) Input Inrush Current at Startup IOUT = 0A, VOUT = 1.5V, FCB = 0 VIN = 5V VIN = 12V VIN = 24V IOUT = 0A, EXTVCC Open VIN = 12V, VOUT = 1.5V, FCB = 5V VIN = 12V, VOUT = 1.5V, FCB = 0V VIN = 24V, VOUT = 2.5V, FCB = 5V VIN = 24V, VOUT = 2.5V, FCB = 0V Shutdown, RUN = 0.8V, VIN = 12V V 0.6 0.7 0.8 A A A Min On Time 1.2 42 1.8 36 35 100 mA mA mA mA μA ns Min Off Time 400 ns 1.52 3.13 3.64 1.6 A A A A IQ(VIN) IS(VIN) 2 Input Supply Bias Current Input Supply Current VIN = 12V, VOUT = 1.5V, IOUT = 10A VIN = 12V, VOUT = 3.3V, IOUT = 10A VIN = 5V, VOUT = 1.5V, IOUT = 10A VIN = 24V to 3.3V at 10A, EXTVCC = 5V 75 4600hvfc LTM4600HV ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VIN = 12V. External CIN = 120μF, COUT = 200μF/Ceramic per typical application (front page) configuration. SYMBOL PARAMETER Output Specifications IOUTDC ΔVOUT(LINE) Output Continuous Current Range (See Output Current Derating Curves for Different VIN, VOUT and TA) Line Regulation Accuracy VOUT ΔVOUT(LOAD) Load Regulation Accuracy CONDITIONS MIN VIN = 12V, VOUT = 1.5V VIN = 24V, VOUT = 2.5V (Note 3) VOUT = 1.5V. FCB = 0V, IOUT = 0A, VIN = 4.5V to 28V VOUT(AC) Output Ripple Voltage VOUT = 1.5V. FCB = 0V, IOUT = 0A to 10A VIN = 5V VIN = 12V (Note 4) VIN = 12V, VOUT = 1.5V, FCB = 0V, IOUT = 0A fs Output Ripple Voltage Frequency FCB = 0V, IOUT = 5A, VIN = 12V, VOUT = 1.5V tSTART Turn-On Time VOUT tSETTLE VOUT = 1.5V, IOUT = 1A VIN = 12V VIN = 5V Voltage Drop for Dynamic Load Step VOUT = 1.5V, Load Step: 0A/μs to 5A/μs COUT = 3 • 22μF 6.3V, 470μF 4V POSCAP, See Table 2 Settling Time for Dynamic Load Step VIN = 12V Load: 10% to 90% to 10% of Full Load IOUTPK Output Current Limit ΔVOUTLS TYP 0 0 ● UNITS 10 10 A A 0.15 0.3 % % % 10 ±1 ±1.5 15 ● Output Voltage in Foldback VIN = 24V, VOUT = 2.5V VIN = 12V, VOUT = 1.5V VIN = 5V, VOUT = 1.5V MAX mVP-P 850 kHz 0.5 0.7 36 ms ms mV 25 μs 17 17 17 A A A Control Stage VOSET Voltage at VOSET Pin VRUN/SS RUN ON/OFF Threshold IRUN(C)/SS Soft-Start Charging Current IRUN(D)/SS Soft-Start Discharging Current VIN – SVIN IEXTVCC Current into EXTVCC Pin RFBHI Resistor Between VOUT and VOSET Pins VFCB Forced Continuous Threshold IFCB Forced Continuous Pin Current IOUT = 0A, VOUT = 1.5V ● 0.591 0.594 0.8 0.6 0.6 1.5 0.609 0.606 2 V V V VRUN/SS = 0V –0.5 –1.2 –3 μA VRUN/SS = 4V 0.8 1.8 3 μA EXTVCC = 0V, FCB = 0V 100 mV EXTVCC = 5V, FCB = 0V, VOUT = 1.5V, IOUT = 0A 16 mA 100 kΩ 0.57 VFCB = 0.6V 0.6 0.63 V –1 –2 μA PGOOD Output ΔVOSETH PGOOD Upper Threshold VOSET Rising 7.5 10 12.5 % ΔVOSETL PGOOD Lower Threshold VOSET Falling –7.5 –10 –12.5 % ΔVOSET(HYS) PGOOD Hysteresis VOSET Returning VPGL PGOOD Low Voltage IPGOOD = 5mA 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 LTM4600HVE is guaranteed to meet performance specifications from 0°C to 85°C. Specifications over the –40°C to 85°C 2 0.15 % 0.4 V operating temperature range are assured by design, characterization and correlation with statistical process controls. The LTM46000HVMP is guaranteed and tested over the –55°C to 125°C temperature range. For output current derating at high temperature, please refer to Thermal Considerations and Output Current Derating discussion. Note 3: Refer to current de-rating curves and thermal application note. Note 4: Test assumes current derating versus temperature. 4600hvfc 3 LTM4600HV U W TYPICAL PERFOR A CE CHARACTERISTICS (See Figure 21 for all curves) Efficiency vs Load Current with 5VIN (FCB = 0) Efficiency vs Load Current with 24VIN (FCB = 0) Efficiency vs Load Current with 12VIN (FCB = 0) 90 90 90 80 80 80 70 60 50 30 0 2 8 6 4 LOAD CURRENT (A) 70 60 0.6VOUT 1.2VOUT 1.5VOUT 2.5VOUT 3.3VOUT 50 0.6VOUT 1.2VOUT 1.5VOUT 2.5VOUT 40 EFFICIENCY (%) 100 EFFICIENCY (%) 100 EFFICIENCY (%) 100 40 10 30 0 2 4 6 LOAD CURRENT (A) 4600hv G01 Efficiency vs Load Current with Different FCB Settings 8 70 60 50 1.8VOUT 2.5VOUT 3.3VOUT 5VOUT 40 30 10 0 2 4 6 LOAD CURRENT (A) 10 4600hv G03 4600hv G02 1.2V Transient Response 8 1.5V Transient Response 90 FCB > 0.7V 80 VOUT = 50mV/DIV EFFICIENCY (%) 70 60 FCB = GND IOUT = 5A/DIV 50 40 30 20 0.1 VIN = 12V VOUT = 1.5V 1 LOAD CURRENT (A) 10 25μs/DIV 1.2V AT 5A/μs LOAD STEP COUT = 3 • 22μF 6.3V CERAMICS 470μF 4V SANYO POSCAP C3 = 100pF 4600hv G05 25μs/DIV 1.5V AT 5A/μs LOAD STEP COUT = 3 • 22μF 6.3V CERAMICS 470μF 4V SANYO POSCAP C3 = 100pF 4600hv G06 4600hv G04 2.5V Transient Response 1.8V Transient Response 25μs/DIV 1.8V AT 5A/μs LOAD STEP COUT = 3 • 22μF 6.3V CERAMICS 470μF 4V SANYO POSCAP C3 = 100pF 4600hv G07 25μs/DIV 2.5V AT 5A/μs LOAD STEP COUT = 3 • 22μF 6.3V CERAMICS 470μF 4V SANYO POSCAP C3 = 100pF 3.3V Transient Response 4600hv G08 25μs/DIV 3.3V AT 5A/μs LOAD STEP COUT = 3 • 22μF 6.3V CERAMICS 470μF 4V SANYO POSCAP C3 = 100pF 4600hv G09 4600hvfc 4 LTM4600HV U W TYPICAL PERFOR A CE CHARACTERISTICS (See Figure 21 for all curves) Start-Up, IOUT = 10A (Resistive Load) Start-Up, IOUT = 0A VOUT (0.5V/DIV) VOUT (0.5V/DIV) IIN (0.5A/DIV) IIN (0.5A/DIV) 200μs/DIV VIN = 12V VOUT = 1.5V COUT = 200μF NO EXTERNAL SOFT-START CAPACITOR Short-Circuit Protection, IOUT = 0A Short-Circuit Protection, IOUT = 10A VIN to VOUT Stepdown Ratio 5.5 fADJ = OPEN 5.0 VOUT (0.5V/DIV) VOUT (0.5V/DIV) 5V 4.5 4.0 IIN (0.5A/DIV) 4600hv G12 20μs/DIV VIN = 12V VOUT = 1.5V COUT = 2× 200μF/X5R NO EXTERNAL SOFT-START CAPACITOR 3.3V 3.5 VOUT (V) IIN (0.2A/DIV) 20μs/DIV VIN = 12V VOUT = 1.5V COUT = 2× 200μF/X5R NO EXTERNAL SOFT-START CAPACITOR 4600hv G11 200μs/DIV VIN = 12V VOUT = 1.5V COUT = 200μF NO EXTERNAL SOFT-START CAPACITOR 4600hv G10 4600hv G13 3.0 2.5V 2.5 1.8V 2.0 1.5V 1.5 1.0 1.2V 0.5 0.6V 0 0 10 5 15 VIN (V) 20 24 SEE FREQUENCY ADJUSTMENT DISCUSSION FOR 12VIN TO 5VOUT AND 5VIN TO 3.3VOUT CONVERSION 4600HV G14 VOSET vs Temperature Start-Up Waveform, TA = –55°C 0.610 VOSET(V) 0.605 0.600 0.595 0.590 –55 VIN = 12V VOUT = 1.5V IOUT = 10A –25 5 35 65 TEMPERATURE (°C) 95 400μs/DIV 4600HV G16 125 4600HV G15 4600hvfc 5 LTM4600HV U U U PI FU CTIO S (See Package Description for Pin Assignment) SGND (Pin D23): Signal Ground Pin. All small-signal components should connect to this ground, which in turn connects to PGND at one point. VIN (Bank 1): Power Input Pins. Apply input voltage between these pins and GND pins. Recommend placing input decoupling capacitance directly between VIN pins and GND pins. RUN/SS (Pin F23): Run and Soft-Start Control. Forcing this pin below 0.8V will shut down the power supply. Inside the power module, there is a 1000pF capacitor which provides approximately 0.7ms soft-start time with 200μF output capacitance. Additional soft-start time can be achieved by adding additional capacitance between the RUN/SS and SGND pins. The internal short-circuit latchoff can be disabled by adding a resistor between this pin and the VIN pin. This resistor must supply a minimum 5μA pull up current. fADJ (Pin A15): A 110k resistor from VIN to this pin sets the one-shot timer current, thereby setting the switching frequency. The LTM4600HV switching frequency is typically 850kHz. An external resistor to ground can be selected to reduce the one-shot timer current, thus lower the switching frequency to accommodate a higher duty cycle step down requirement. See the applications section. SVIN (Pin A17): Supply Pin for Internal PWM Controller. Leave this pin open or add additional decoupling capacitance. EXTVCC (Pin A19): External 5V supply pin for controller. If left open or grounded, the internal 5V linear regulator will power the controller and MOSFET drivers. For high input voltage applications, connecting this pin to an external 5V will reduce the power loss in the power module. The EXTVCC voltage should never be higher than VIN. FCB (Pin G23): Forced Continuous Input. Grounding this pin enables forced continuous mode operation regardless of load conditions. Tying this pin above 0.63V enables discontinuous conduction mode to achieve high efficiency operation at light loads. There is an internal 4.75K resistor between the FCB and SGND pins. VOSET (Pin A21): The Negative Input of The Error Amplifier. Internally, this pin is connected to VOUT with a 100k precision resistor. Different output voltages can be programmed with additional resistors between the VOSET and SGND pins. PGOOD (Pin J23): Output Voltage Power Good Indicator. When the output voltage is within 10% of the nominal voltage, the PGOOD is open drain output. Otherwise, this pin is pulled to ground. COMP (Pin B23): Current Control Threshold and Error Amplifier Compensation Point. The current comparator threshold increases with this control voltage. The voltage ranges from 0V to 2.4V with 0.8V corresponding to zero sense voltage (zero current). PGND (Bank 2): Power ground pins for both input and output returns. VOUT (Bank 3): Power Output Pins. Apply output load between these pins and GND pins. Recommend placing High Frequency output decoupling capacitance directly between these pins and GND pins. 5 6 7 VOSET 4 EXTVCC 3 SVIN 2 fADJ TOP VIEW 16 17 18 19 1 VIN BANK 1 9 10 8 13 14 C 22 E 23 25 26 27 28 29 30 31 33 34 35 36 37 38 24 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 1 3 2 5 4 7 6 9 8 11 10 13 12 15 14 17 16 B SGND F RUN/SS G 19 18 21 20 J COMP D H 32 VOUT BANK 3 A 15 12 PGND BANK 2 20 21 11 K FCB PGOOD L M N P R T 23 22 4600hv PN01 4600hvfc 6 LTM4600HV W W SI PLIFIED BLOCK DIAGRA SVIN RUN/SS LTM4600HV VIN, 4.5V TO 28V ABS MAX 1000pF CIN 1.5μF PGOOD Q1 COMP INT COMP VOUT, 2.5V/10A MAX FCB COUT 4.75k 15μF 6.3V CONTROLLER fADJ SGND PGND Q2 10Ω EXTVCC 100k 0.5% VOSET R6 31.6k 4600hv F01 Figure 1. Simplified LTM4600HV Block Diagram U W U DECOUPLI G REQUIRE E TS TA = 25°C, VIN = 12V. Use Figure 1 configuration. SYMBOL PARAMETER CONDITIONS MIN CIN External Input Capacitor Requirement (VIN = 4.5V to 28V, VOUT = 2.5V) IOUT = 10A, 2x 10μF 35V Ceramic Taiyo Yuden GDK316BJ106ML 20 COUT External Output Capacitor Requirement (VIN = 4.5V to 28V, VOUT = 2.5V) IOUT = 10A, Refer to Table 2 in the Applications Information Section 100 TYP MAX UNITS μF 200 μF 4600hvfc 7 LTM4600HV U OPERATIO μModule Description The LTM4600HV is a standalone non-isolated synchronous switching DC/DC power supply. It can deliver up to 10A of DC output current with only bulk external input and output capacitors. This module provides a precisely regulated output voltage programmable via one external resistor from 0.6VDC to 5.0VDC. The input voltage range is 4.5V to 28V. A simplified block diagram is shown in Figure 1 and the typical application schematic is shown in Figure 21. The LTM4600HV contains an integrated LTC constant on-time current-mode regulator, ultra-low RDS(ON) FETs with fast switching speed and integrated Schottky diode. The typical switching frequency is 850kHz at full load. With current mode control and internal feedback loop compensation, the LTM4600HV module has sufficient 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 (X5R or X7R for extended temperature range). Current mode control provides cycle-by-cycle fast current limit. In addition, foldback current limiting is provided in an over-current condition while VOSET drops. Also, the LTM4600HV has defeatable short circuit latch off. 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/SS pin low forces the controller into its shutdown state, turning off both Q1 and Q2. Releasing the pin allows an internal 1.2μA current source to charge up the softstart capacitor. When this voltage reaches 1.5V, the controller turns on and begins switching. At low load current the module works in continuous current mode by default to achieve minimum output voltage ripple. It can be programmed to operate in discontinuous current mode for improved light load efficiency when the FCB pin is pulled up above 0.8V and no higher than 6V. The FCB pin has a 4.75k resistor to ground, so a resistor to VIN can set the voltage on the FCB pin. When EXTVCC pin is grounded or open, an integrated 5V linear regulator powers the controller and MOSFET gate drivers. If a minimum 4.7V external bias supply is applied on the EXTVCC pin, the internal regulator is turned off, and an internal switch connects EXTVCC to the gate driver voltage. This eliminates the linear regulator power loss with high input voltage, reducing the thermal stress on the controller. The maximum voltage on EXTVCC pin is 6V. The EXTVCC voltage should never be higher than the VIN voltage. Also EXTVCC must be sequenced after VIN. Recommended for 24V operation to lower temperature in the μModule. 4600hvfc 8 LTM4600HV U U W U APPLICATIO S I FOR ATIO The typical LTM4600HV application circuit is shown in Figure 21. External component selection is primarily determined by the maximum load current and output voltage. Output Voltage Programming and Margining The PWM controller of the LTM4600HV has an internal 0.6V±1% reference voltage. As shown in the block diagram, a 100k/0.5% internal feedback resistor connects VOUT and VOSET pins. Adding a resistor RSET from VOSET pin to SGND pin programs the output voltage: VO = 0.6V • 100k + RSET RSET Table 1. RSET (kΩ) Open 100 66.5 49.9 43.2 31.6 22.1 13.7 VO (V) 0.6 1.2 1.5 1.8 2 2.5 3.3 5 Voltage margining is the dynamic adjustment of the output voltage to its worst case operating range in production testing to stress the load circuitry, verify control/protection functionality of the board and improve the system reliability. Figure 2 shows how to implement margining function with the LTM4600HV. In addition to the feedback resistor RSET, several external components are added. Turn off both transistor QUP and QDOWN to disable the margining. When QUP is on and QDOWN is off, the output VOUT RDOWN 100k QDOWN 2N7002 VOSET PGND SGND (RSET RUP )• VO •(1+ M%) = 0.6V (RSET RUP ) + 100kΩ RSET • VO •(1– M%) = 0.6V RSET + (100kΩ RDOWN) Input Capacitors Table 1 shows the standard values of 1% RSET resistor for typical output voltages: LTM4600HV voltage is margined up. The output voltage is margined down when QDOWN is on and QUP is off. If the output voltage VO needs to be margined up/down by ±M%, the resistor values of RUP and RDOWN can be calculated from the following equations: RSET RUP QUP 2N7002 4600hv F02 Figure 2. LTM4600HV Margining Implementation The LTM4600HV μModule should be connected to a low ac-impedance DC source. High frequency, low ESR input capacitors are required to be placed adjacent to the module. In Figure 21, the bulk input capacitor CIN is selected for its ability to handle the large RMS current into the converter. For a buck converter, the switching duty-cycle can be estimated as: D= VO VIN Without considering the inductor current ripple, the RMS current of the input capacitor can be estimated as: ICIN(RMS) = IO(MAX) • D •(1− D) η% In the above equation, η% is the estimated efficiency of the power module. C1 can be a switcher-rated electrolytic aluminum capacitor, OS-CON capacitor or high volume ceramic capacitors. Note the capacitor ripple current ratings are often based on only 2000 hours of life. This makes it advisable to properly derate the input capacitor, or choose a capacitor rated at a higher temperature than required. Always contact the capacitor manufacturer for derating requirements over temperature. In Figure 21, the input capacitors are used as high frequency input decoupling capacitors. In a typical 10A output application, 1-2 pieces of very low ESR X5R or X7R (for extended temperature range), 10μF ceramic capacitors are recommended. This decoupling capacitor 4600hvfc 9 LTM4600HV U W U U APPLICATIO S I FOR ATIO should be placed directly adjacent the module input pins in the PCB layout to minimize the trace inductance and high frequency AC noise. Output Capacitors The LTM4600HV is designed for low output voltage ripple. The bulk output capacitors COUT is chosen with low enough effective series resistance (ESR) to meet the output voltage ripple and transient requirements. COUT can be low ESR tantalum capacitor, low ESR polymer capacitor or ceramic capacitor (X5R or X7R). The typical capacitance is 200μF if all ceramic output capacitors are used. The internally optimized loop compensation provides sufficient stability margin for all ceramic capacitors applications. Additional output filtering may be required by the system designer, if further reduction of output ripple or dynamic transient spike is required. Refer to Table 2 for an output capacitance matrix for each output voltage Droop, peak to peak deviation and recovery time during a 5A/μs transient with a specific output capacitance. Fault Conditions: Current Limit and Over current Foldback The LTM4600HV has a current mode controller, which inherently 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 over load condition, the LTM4600HV 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 Latchoff with the RUN/SS pin The RUN/SS pin provides a means to shut down the LTM4600HV as well as a timer for soft-start and overcurrent latchoff. Pulling the RUN/SS pin below 0.8V puts the LTM4600HV into a low quiescent current shutdown (IQ ≤ 75μA). Releasing the pin allows an internal 1.2μA current source to charge up the timing capacitor CSS. Inside LTM4600HV, there is an internal 1000pF capacitor from RUN/SS pin to ground. If RUN/SS pin has an external capacitor CSS_EXT to ground, the delay before starting is about: tDELAY = 1.5V •(C SS _ EXT + 1000pF ) 1.2μA When the voltage on RUN/SS pin reaches 1.5V, the LTM4600HV internal switches are operating with a clamping of the maximum output inductor current limited by the RUN/SS pin total soft-start capacitance. As the RUN/SS pin voltage rises to 3V, the soft-start clamping of the inductor current is released. VIN to VOUT Stepdown Ratios There are restrictions in the maximum VIN to VOUT step down ratio that can be achieved for a given input voltage. These contraints are shown in the Typical Performance Characteristics curves labeled “VIN to VOUT Stepdown Ratio”. Note that additional thermal de-rating may apply. See the Thermal Considerations and Output Current DeRating sections of this data sheet. 4600hvfc 10 LTM4600HV U W U U APPLICATIO S I FOR ATIO Table 2. Output Voltage Response Versus Component Matrix *(Refer to Figure 21) TYPICAL MEASURED VALUES COUT1 VENDORS TDK TAIYO YUDEN TAIYO YUDEN TAIYO YUDEN PART NUMBER C4532X5R0J107MZ (100μF,6.3V) JMK432BJ107MU-T ( 100μF, 6.3V) JMK316BJ226ML-T501 ( 22μF, 6.3V) JMK316BJ226ML-T501 ( 22μF, 6.3V) VOUT CIN CIN COUT1 (V) (CERAMIC) (BULK) (CERAMIC) 1.2 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 1.2 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 1.2 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 1.2 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V 1.2 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 1.2 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 1.2 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 1.2 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V 1.5 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 1.5 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 1.5 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 1.5 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V 1.5 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 1.5 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 1.5 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 1.5 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V 1.8 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 1.8 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 1.8 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 1.8 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V 1.8 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 1.8 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 1.8 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 1.8 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V 2.5 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 2.5 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 2.5 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 2.5 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V 2.5 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 2.5 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 2.5 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 2.5 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V 2.5 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 2.8 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 3.3 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 3.3 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 3.3 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 3.3 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V 3.3 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 3.3 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 3.3 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 3.3 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V 3.3 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 5 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V 5 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V *X7R is recommended for extended temperature range. COUT2 (BULK) 470μF 4V 470μF 2.5V 330μF 6.3V NONE 470μF 4V 470μF 2.5V 330μF 6.3V NONE 470μF 4V 470μF 2.5V 330μF 6.3V NONE 470μF 4V 470μF 2.5V 330μF 6.3V NONE 470μF 4V 470μF 2.5V 330μF 6.3V NONE 470μF 4V 470μF 2.5V 330μF 6.3V NONE 470μF 4V 330μF 6.3V 470μF 4V NONE 470μF 4V 470μF 4V 330μF 6.3V NONE 470μF 6.3V 470μF 6.3V 330μF 6.3V 470μF 4V 470μF 4V NONE 470μF 4V 470μF 4V 330μF 6.3V NONE 470μF 6.3V NONE NONE COUT2 VENDORS SANYO POSCAP SANYO POSCAP SANYO POSCAP SANYO POSCAP CCOMP C3 NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE NONE 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF 100pF VIN (V) 5 5 5 5 12 12 12 12 5 5 5 5 12 12 12 12 5 5 5 5 12 12 12 12 5 5 5 5 12 12 12 12 24 24 7 7 7 7 12 12 12 12 24 15 20 DROOP (mV) 35 35 40 49 35 35 40 49 36 37 44 61 36 37 44 54 40 44 46 62 40 44 44 62 48 56 57 60 48 51 56 70 56 50 64 66 82 100 52 64 64 76 74 188 159 PART NUMBER 6TPE330MIL (330μF, 6.3V) 2R5TPE470M9 (470μF, 2.5V) 4TPE470MCL (470μF, 4V) 6TPD470M (470μF, 6.3V) PEAK TO PEAK (mV) 68 70 80 98 68 70 80 98 75 79 84 118 75 79 89 108 81 88 91 128 81 85 91 125 103 113 116 115 103 102 113 159 112 100 126 132 166 200 106 129 126 144 149 375 320 RECOVERY TIME (μs) 25 20 20 20 25 20 20 20 25 20 20 20 25 20 20 20 30 20 20 20 30 20 20 20 30 30 30 25 30 30 30 25 30 30 30 30 35 25 30 35 30 25 30 25 25 LOAD STEP (A/μs) 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 4600hvfc 11 LTM4600HV U W U U APPLICATIO S I FOR ATIO After the controller has been started and given adequate time to charge up the output capacitor, CSS is used as a short-circuit timer. After the RUN/SS pin charges above 4V, if the output voltage falls below 75% of its regulated value, then a short-circuit fault is assumed. A 1.8μA current then begins discharging CSS. If the fault condition persists until the RUN/SS pin drops to 3.5V, then the controller turns off both power MOSFETs, shuting down the converter permanently. The RUN/SS pin must be actively pulled down to ground in order to restart operation. The over-current protection timer requires the soft-start timing capacitor CSS be made large enough to guarantee that the output is in regulation by the time CSS has reached the 4V threshold. In general, this will depend upon the size of the output capacitance, output voltage and load current characteristic. A minimum external soft-start capacitor can be estimated from: C SS _ EXT + 1000pF > C OUT • VOUT (10–3 [F / VS ]) Generally 0.1μF is more than sufficient. Since the load current is already limited by the current mode control and current foldback circuitry during a shortcircuit, over-current latchoff operation is NOT always needed or desired, especially the output has large amount of capacitance or the load draw huge current during start up. The latchoff feature can be overridden by a pull-up current greater than 5μA but less than 80μA to the RUN/SS pin. The additional current prevents the discharge of CSS during a fault and also shortens the soft-start period. Using a resistor from RUN/SS pin to VIN is a simple solution to defeat latchoff. Any pull-up network must be able to maintain RUN/SS above 4V maximum latchoff threshold and overcome the 4μA maximum discharge current. Figure 3 shows a conceptual drawing of VRUN during startup and short circuit. VRUN/SS 4V 3.5V 3V 1.5V SHORT-CIRCUIT LATCH ARMED t SOFT-START CLAMPING OF IL RELEASED OUTPUT OVERLOAD HAPPENS SHORT-CIRCUIT LATCHOFF VO 75%VO t SWITCHING STARTS 4600hv F03 Figure 3. RUN/SS Pin Voltage During Startup and Short-Circuit Protection VIN RRUN/SS VIN RECOMMENDED VALUES FOR RUN/SS LTM4600HV RUN/SS PGND SGND VIN RRUN/SS 4.5V TO 5.5V 10.8V TO 13.8V 24V TO 28V 50k 150k 500k 4600hv F04 Figure 4. Defeat Short-Circuit Latchoff with a Pull-Up Resistor to VIN 4600hvfc 12 LTM4600HV U U W U APPLICATIO S I FOR ATIO Enable EXTVCC Connection The RUN/SS pin can be driven from logic as shown in Figure 5. This function allows the LTM4600HV to be turned on or off remotely. The ON signal can also control the sequence of the output voltage. An internal low dropout regulator produces an internal 5V supply that powers the control circuitry and FET drivers. Therefore, if the system does not have a 5V power rail, the LTM4600HV can be directly powered by VIN. The gate driver current through LDO is about 18mA. The internal LDO power dissipation can be calculated as: RUN/SS PLDO_LOSS = 18mA • (VIN – 5V) LTM4600HV ON PGND SGND 2N7002 4600hv F05 Figure 5. Enable Circuit with External Logic Output Voltage Tracking For the applications that require output voltage tracking, several LTM4600HV modules can be programmed by the power supply tracking controller such as the LTC2923. Figure 6 shows a typical schematic with LTC2923. Coincident, ratiometric and offset tracking for VO rising and falling can be implemented with different sets of resistor values. See the LTC2923 data sheet for more details. Q1 VIN 5V 3.3V DC/DC VIN VIN RONB VCC RAMP GATE ON RONA FB1 VIN TRACK1 SDO VIN TRACK2 FB2 LTM4600HV VOSET VOUT RTB2 RTA2 GND 2. EXTVCC connected to an external supply. Internal LDO is shut off. A high efficiency supply compatible with the MOSFET gate drive requirements (typically 5V) can improve overall efficiency. With this connection, it is always required that the EXTVCC voltage can not be higher than VIN pin voltage. 3. EXTVCC is recommended for VIN > 20V Discontinuous Operation and FCB Pin STATUS RTB1 RTA1 1.8V 1. EXTVCC grounded. Internal 5V LDO is always powered from the internal 5V regulator. 49.9k LTC2923 RAMPBUF LTM4600HV VOSET VOUT The LTM4600HV also provides an external gate driver voltage pin EXTVCC. If there is a 5V rail in the system, it is recommended to connect EXTVCC pin to the external 5V rail. Whenever the EXTVCC pin is above 4.7V, the internal 5V LDO is shut off and an internal 50mA P-channel switch connects the EXTVCC to internal 5V. Internal 5V is supplied from EXTVCC until this pin drops below 4.5V. Do not apply more than 6V to the EXTVCC pin and ensure that EXTVCC < VIN. The following list summaries the possible connections for EXTVCC: 1.5V 66.5k 4600hv F06 The FCB pin determines whether the internal bottom MOSFET remains on when the current reverses. There is an internal 4.75k pull-down resistor connecting this pin to ground. The default light load operation mode is forced continuous (PWM) current mode. This mode provides minimum output voltage ripple. Figure 6. Output Voltage Tracking with the LTC2923 Controller 4600hvfc 13 LTM4600HV U U W U APPLICATIO S I FOR ATIO In the application where the light load efficiency is important, tying the FCB pin above 0.6V threshold enables discontinuous operation where the bottom MOSFET turns off when inductor current reverses. Therefore, the conduction loss is minimized and light load efficiency is improved. The penalty is that the controller may skip cycle and the output voltage ripple increases at light load. Paralleling Operation with Load Sharing Two or more LTM4600HV modules can be paralleled to provide higher than 10A output current. Figure 7 shows the necessary interconnection between two paralleled modules. The OPTI-LOOP™ current mode control ensures good current sharing among modules to balance the thermal stress. The new feedback equation for two or more LTM4600HVs in parallel is: 100k + RSET N VOUT = 0.6 V • RSET VIN VOUT LTM4600HV VOUT (20AMAX) PGND COMP VOSET SGND RSET COMP VOSET SGND VIN LTM4600HV Safety Considerations The LTM4600HV modules do not provide isolation from VIN to VOUT. There is no internal fuse. If required, a slow blow fuse with a rating twice the maximum input current should be provided to protect each unit from catastrophic failure. Layout Checklist/Example where N is the number of LTM4600HVs in parallel. VIN explanation of the analysis for the thermal models, and the derating curves. Tables 3 and 4 provide a summary of the equivalent θJA for the noted conditions. These equivalent θJA parameters are correlated to the measure values, and improved with air-flow. The case temperature is maintained at 100°C or below for the derating curves. This allows for 4W maximum power dissipation in the total module with top and bottom heatsinking, and 2W power dissipation through the top of the module with an approximate θJC between 6°C/W to 9°C/W. This equates to a total of 124°C at the junction of the device. VOUT PGND The high integration of the LTM4600HV makes the PCB board layout very simple and easy. However, to optimize its electrical and thermal performance, some layout considerations are still necessary. • Use large PCB copper areas for high current path, including VIN, PGND and VOUT. It helps to minimize the PCB conduction loss and thermal stress • Place high frequency ceramic input and output capacitors next to the VIN, PGND and VOUT pins to minimize high frequency noise 4600hv F07 Figure 7. Parallel Two μModules with Load Sharing Thermal Considerations and Output Current Derating The power loss curves in Figures 8 and 15 can be used in coordination with the load current derating curves in Figures 9 to 14, and Figures 16 to 19 for calculating an approximate θJA for the module with various heatsinking methods. Thermal models are derived from several temperature measurements at the bench, and thermal modeling analysis. Application Note 103 provides a detailed OPTI-LOOP is a trademark of Linear Technology Corporation. • Place a dedicated power ground layer underneath the unit • 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 pad unless they are capped. • Use a separated SGND ground copper area for components connected to signal pins. Connect the SGND to PGND underneath the unit Figure 20 gives a good example of the recommended layout. 4600hvfc 14 LTM4600HV U U W U APPLICATIO S I FOR ATIO 10 POWER LOSS (W) 3.5 18V LOSS 3.0 2.5 12V LOSS 2.0 1.5 5V LOSS 1.0 9 8 7 6 5 0 LFM 200 LFM 400 LFM 0.5 4 0 2 0 4 6 8 OUTPUT CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) 4.0 10 50 60 80 70 AMBIENT TEMPERATURE (°C) Figure 8. 1.5V Power Loss Curves vs Load Current 6 5 0 LFM 200 LFM 400 LFM 50 55 9 7 6 5 3 90 0 LFM 200 LFM 400 LFM 50 POWER LOSS (W) MAXIMUM LOAD CURRENT (A) 7 6 5 4 3 2 0 60 70 80 90 AMBIENT TEMPERATURE (°C) 100 0 LFM 200 LFM 400 LFM 40 4 10 4.5 9 3.5 24V LOSS 2.5 2.0 12V LOSS 1.5 100 8 7 6 5 4 3 2 0 0 0 2 4 6 8 OUTPUT CURRENT (A) 4600hv F14 Figure 14. BGA Heatsink VIN = 12V VOUT = 3.3V 0 LFM 200 LFM 400 LFM 1 0.5 80 90 60 70 AMBIENT TEMPERATURE (°C) 10 40 50 60 80 70 AMBIENT TEMPERATURE (°C) 90 4600hv F16 4600hv F15 Figure 15. 3.3V Power Loss Curves vs Load Current 90 Figure 13. No Heatsink 1.0 0 LFM 200 LFM 400 LFM 60 80 50 70 AMBIENT TEMPERATURE (°C) 4600hv F13 5.0 3.0 100 8 1 4.0 6 60 70 80 90 AMBIENT TEMPERATURE (°C) VIN = 18V VOUT = 1.5V Figure 12. BGA Heatsink VIN = 18V VOUT = 1.5V 50 50 4600hv F12 8 0 0 LFM 200 LFM 400 LFM 9 8 Figure 11. No Heatsink 2 5 10 4600hv F11 10 6 Figure 10. BGA Heatsink VIN = 12V VOUT = 1.5V 4 60 65 70 75 80 85 AMBIENT TEMPERATURE (°C) 7 4600hv F10 MAXIMUM LOAD CURRENT (A) 7 4 10 MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) 8 8 Figure 9. No Heatsink VIN = 12V VOUT = 1.5V 9 9 4 90 VIN = 5V VOUT = 1.5V 4600hv F09 4600hv F08 10 10 VIN = 5V VOUT = 1.5V VOUT = 1.5V MAXIMUM LOAD CURRENT (A) 4.5 Figure 16. No Heatsink 4600hvfc 15 LTM4600HV U U W U APPLICATIO S I FOR ATIO 9 8 7 6 5 4 0 LFM 200 LFM 400 LFM 40 60 70 80 90 50 AMBIENT TEMPERATURE (°C) 100 VIN = 24V VOUT = 3.3V TEMPERATURE DE-RATING 8 6 4 2 0 0 LFM 200 LFM 400 LFM 50 60 80 70 AMBIENT TEMPERATURE (°C) 4600hv F17 Figure 17. BGA Heatsink 90 10 MAXIMUM LOAD CURRENT (A) 10 VIN = 12V VOUT = 3.3V MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) 10 0 LFM 200 LFM 400 LFM 9 8 7 6 5 VIN = 24V VOUT = 3.3V TEMPERATURE DE-RATING 4 60 70 80 50 AMBIENT TEMPERATURE (°C) 4600hv F18.eps 90 4600hv F19.eps Figure 18. No Heatsink Figure 19. BGA Heatsink Table 3. 1.5V Output DERATING CURVE VIN (V) POWER LOSS CURVE AIR FLOW (LFM) HEATSINK θJA (°C/W) Figures 9, 11, 13 5, 12, 18 Figure 8 0 None 15.2 Figures 9, 11, 13 5, 12, 18 Figure 8 200 None 14 Figures 9, 11, 13 5, 12, 18 Figure 8 400 None 12 Figures 10, 12, 14 5, 12, 18 Figure 8 0 BGA Heatsink 13.9 Figures 10, 12, 14 5, 12, 18 Figure 8 200 BGA Heatsink 11.3 Figures 10, 12, 14 5, 12, 18 Figure 8 400 BGA Heatsink 10.25 DERATING CURVE VIN (V) POWER LOSS CURVE AIR FLOW (LFM) HEATSINK θJA (°C/W) Figures 16, 18 12, 24 Figure 15 0 None 15.2 Figures 16, 18 12, 24 Figure 15 200 None 14.6 Figures 16, 18 12, 24 Figure 15 400 None 13.4 Figures 17, 19 12, 24 Figure 15 0 BGA Heatsink 13.9 Figures 17, 19 12, 24 Figure 15 200 BGA Heatsink 11.1 Figures 17, 19 12, 24 Figure 15 400 BGA Heatsink 10.5 Table 4. 3.3V Output 4600hvfc 16 LTM4600HV U W U U APPLICATIO S I FOR ATIO VIN t (DC) DUTY CYCLE = ON ts tOFF CIN tON V t DC = ON = OUT ts VIN DC FREQ = tON 4602 F25 PERIOD ts PGND VOUT 4600hv F20 LOAD TOP LAYER Figure 20. Recommended PCB Layout LTM4600HV Frequency Adjustment The LTM4600HV is designed to typically operate at 850kHz across most input and output conditions. The control architecture is constant on time valley mode current control. The fADJ pin is typically left open or decoupled with an optional 1000pF capacitor. The switching frequency has been optimized to maintain constant output ripple over the operating conditions. The equations for setting the operating frequency are set around a programmable constant on time. This on time is developed by a programmable current into an on board 10pF capacitor that establishes a ramp that is compared to a voltage threshold equal to the output voltage up to a 2.4V clamp. This ION current is equal to: ION = (VIN – 0.7V)/110k, with the 110k onboard resistor from VIN to fADJ. The on time is equal to tON = (VOUT/ION) • 10pF and tOFF = ts – tON. The frequency is equal to: Freq. = DC/tON. The ION current is proportional to VIN, and the regulator duty cycle is inversely proportional to VIN, therefore the step-down regulator will remain relatively constant frequency as the duty cycle adjustment takes place with lowering VIN. The on time is proportional to VOUT up to a 2.4V clamp. This will hold frequency relatively constant with different output voltages up to 2.4V. The regulator switching period is comprised of the on time and off time as depicted in the following waveform. The on time is equal to tON = (VOUT/ION) • 10pF and tOFF = ts – tON. The frequency is equal to: Frequency = DC/tON). The LTM4600HV has a minimum (tON) on time of 100 nanoseconds and a minimum (tOFF) off time of 400 nanoseconds. The 2.4V clamp on the ramp threshold as a function of VOUT will cause the switching frequency to increase by the ratio of VOUT/2.4V for 3.3V and 5V outputs. This is due to the fact the on time will not increase as VOUT increases past 2.4V. Therefore, if the nominal switching frequency is 850kHz, then the switching frequency will increase to ~1.2MHz for 3.3V, and ~1.7MHz for 5V outputs due to Frequency = (DC/tON) When the switching frequency increases to 1.2MHz, then the time period tS is reduced to ~833 nanoseconds and at 1.7MHz the switching period reduces to ~588 nanoseconds. When higher duty cycle conversions like 5V to 3.3V and 12V to 5V need to be accommodated, then the switching frequency can be lowered to alleviate the violation of the 400ns minimum off time. Since the total switching period is tS = tON + tOFF, tOFF will be below the 400ns minimum off time. A resistor from the fADJ pin to ground can shunt current away from the on time generator, thus allowing for a longer on time and a lower switching frequency. 12V to 5V and 5V to 3.3V derivations are explained in the data sheet to lower switching frequency and accommodate these step-down conversions. Equations for setting frequency for 12V to 5V: ION = (VIN – 0.7V)/110k; ION = 103μA frequency = (ION/[2.4V • 10pF]) • DC = 1.79MHz; DC = duty cycle, duty cycle is (VOUT/VIN) tS = tON + tOFF, tON = on-time, tOFF = off-time of the switching period; tS = 1/frequency tOFF must be greater than 400ns, or tS – tON > 400ns. tON = DC • tS 1MHz frequency or 1μs period is chosen for 12V to 5V. 4600hvfc 17 LTM4600HV U W U U APPLICATIO S I FOR ATIO tOFF must be greater than 400ns, or tS – tON > 400ns. tON = 0.41 • 1μs ≅ 410ns tON = DC • tS tOFF = 1μs – 410ns ≅ 590ns ~450kHz frequency or 2.22μs period is chosen for 5V to 3.3V. Frequency range is about 450kHz to 650kHz from 4.5V to 7V input. tON and tOFF are above the minimums with adequate guard band. Using the frequency = (ION/[2.4V • 10pF]) • DC, solve for ION = (1MHz • 2.4V • 10pF) • (1/0.41) ≅ 58μA. ION current calculated from 12V input was 103μA, so a resistor from fADJ to ground = (0.7V/15k) = 46μA. 103μA – 46μA = 57μA, sets the adequate ION current for proper frequency range for the higher duty cycle conversion of 12V to 5V. Input voltage range is limited to 9V to 16V. Higher input voltages can be used without the 15k on fADJ. The inductor ripple current gets too high above 16V, and the 400ns minimum off-time is limited below 9V. tON = 0.66 • 2.22μs ≅ 1.46μs tOFF = 2.22μs – 1.46μs ≅ 760ns tON and tOFF are above the minimums with adequate guard band. Using the frequency = (ION/[2.4V • 10pF]) • DC, solve for ION = (450kHz • 2.4V • 10pF) • (1/0.66) ≅ 16μA. ION current calculated from 5V input was 39μA, so a resistor from fADJ to ground = (0.7V/30.1k) = 23μA. 39μA – 23μA = 16μA, sets the adequate ION current for proper frequency range for the higher duty cycle conversion of 5V to 3.3V. Input voltage range is limited to 4.5V to 7V. Higher input voltages can be used without the 30.1k on fADJ. The inductor ripple current gets too high above 7V, and the 400ns minimum off-time is limited below 4.5V. Equations for setting frequency for 5V to 3.3V: ION = (VIN – 0.7V)/110k; ION = 39μA frequency = (ION/[2.4V • 10pF]) • DC = 1.07MHz; DC = duty cycle, duty cycle is (VOUT/VIN) tS = tON + tOFF, tON = on-time, tOFF = off-time of the switching period; tS = 1/frequency 5V to 3.3V at 8A R1 30.1k 4.5V TO 7V C3 10μF 25V C1 10μF 25V VIN C5 100pF fADJ EXTVCC 3.3V AT 8A FCB VOSET R2 22.1k 1% LTM4600HV RUN/SOFT-START EFFICIENCY = 94% VOUT RUN/SS SVIN PGOOD COMP SGND C2 22μF + C4 330μF 6.3V OPEN DRAIN PGND 4600 F22 5V TO 3.3V AT 8A WITH fADJ = 30.1k LTM4600HV MINIMUM ON-TIME = 100ns LTM4600HV MINIMUM OFF-TIME = 400ns C1, C3: TDK C3216X5R1E106MT C2: TAIYO YUDEN, JMK316BJ226ML C4: SANYO POSCAP, 6TPE330MIL 4600hvfc 18 LTM4600HV U U W U APPLICATIO S I FOR ATIO 12V to 5V at 8A R1 15k 9V TO 16V C1 10μF 25V VIN 5.0 fADJ 4.0 5V AT 8A EXTVCC EFFICIENCY = 94% VOUT FCB VOSET RUN/SS SVIN PGOOD COMP SGND C2 22μF R2 13.7k 1% LTM4600HV RUN/SOFT-START 3.3V: fADJ = 30.1k 4.5 5V: fADJ = 15k C5 100pF + C4 330μF 6.3V 3.5 VOUT (V) C3 10μF 25V VIN to VOUT Stepdown Ratio for 12V to 5V and 5V to 3.3V 3.0 2.5 2.0 1.5 OPEN DRAIN PGND 1.0 4600 F23 12V TO 5V AT 8A WITH fADJ = 15k LTM4600HV MINIMUM ON-TIME = 100ns LTM4600HV MINIMUM OFF-TIME = 400ns 3.3V AT 8A 5V AT 8A 0.5 0 C1, C3: TDK C3216X5R1E106MT C2: TAIYO YUDEN, JMK316BJ226ML C4: SANYO POSCAP, 6TPE330MIL 1 3 5 7 9 11 VIN (V) 13 15 17 4600 F24 U TYPICAL APPLICATIO VIN + 5V TO 24V CIN (BULK) 150μF CIN (CER) 10μF 2x GND EXTVCC C3 100pF SVIN VIN (MULTIPLE PINS) VOUT (MULTIPLE PINS) fADJ VOSET VOUT LTM4600HV COMP FCB VOUT COUT1 + 22μF 6.3V ×3 REFER TO TABLE 2 RUN/SS PGOOD COUT2 470μF REFER TO TABLE 2 0.6V TO 5V SGND C4 OPT REFER TO STEP DOWN RATIO GRAPH PGND (MULTIPLE PINS) R1 66.5k REFER TO TABLE 1 GND 4600HV F21 Figure 21. Typical Application, 5V to 24V Input, 0.6V to 5V Output, 10A Max 4600hvfc 19 LTM4600HV U TYPICAL APPLICATIO Parallel Operation and Load Sharing 4.5V TO 24V C8 10μF 35V VOUT = 0.6V • ([100k/N] + RSET)/RSET WHERE N = 2 C7 10μF 35V VIN fADJ EXTVCC VOUT FCB C9 22μF x3 VOSET LTM4600HV RUN R4 15.8k 1% SVIN + C10 470μF 4V PGOOD COMP SGND PGND 2.5V AT 20A RUN/SOFT-START C3 10μF 35V C1 10μF 35V VIN C4 220pF fADJ EXTVCC 2.5V VOUT FCB C2 22μF x3 VOSET LTM4600HV RUN + C5 470μF 4V R1 100k SVIN PGOOD COMP SGND PGND C1, C3, C7, C8: TAIYO YUDEN, GDK316BJ106ML C2, C9: TAIYO YUDEN, JMK316BJ226ML-T501 C5, C10: SANYO POSCAP, 4TPE470MCL 4600hv TA02 Current Sharing Between Two LTM4600HV Modules 12 INDIVIDUAL SHARE 12VIN 2.5VOUT 10 20AMAX IOUT2 8 IOUT1 6 4 2 0 0 5 10 TOTAL LOAD 15 20 4600hv TA03 4600hvfc 20 5.7150 2.5400 0.3175 0.3175 2.7375 C(0.30) PAD 1 13.97 BSC 0.11 – 0.27 6.9850 4.4450 1.2700 0.0000 1.4675 4.0075 6.9421 94 83 72 61 50 39 5.7158 102 100 101 80 69 58 47 91 79 68 57 46 38 31 90 37 30 17 18 33 1 1 8 3 5 6 7 4 8 13 10 9 11 6 28 35 55 14 44 13 13.93 BSC 12 10 7 29 36 15 45 56 67 78 89 100 14 11 15 16 30 37 BOTTOM VIEW 9 5 27 34 54 43 66 77 88 99 16 46 57 68 79 90 101 17 17 31 38 18 47 58 69 80 91 102 18 20 48 19 22 49 60 71 70 59 82 93 104 81 92 103 104 93 82 71 60 49 20 24 24 23 22 21 19 21 23 20 21 22 26 53 42 65 76 87 98 12.70 BSC 103 92 81 70 59 48 19 12 4 1.9042 16 3.1742 89 78 67 56 45 99 88 77 66 55 44 36 29 15 11 98 87 76 65 54 43 35 28 14 10 7 5.7142 23 2 3 41 52 40 51 50 86 97 64 85 96 63 61 34 27 13 9 6 4.4442 SUGGESTED SOLDER PAD LAYOUT TOP VIEW 62 73 72 97 86 75 64 53 42 75 84 83 96 85 74 63 52 41 33 26 4.4950 74 95 2 95 84 73 62 51 40 1.0900 94 39 4.4458 2.3600 3.1758 5.7650 1.9058 5 6.9865 25 32 32 25 12 6.3500 8 5.0800 0.0000 1.2700 5.2775 3.8100 0.6358 0.3175 0.3175 0.0000 4 2.5400 0.6342 1.2700 3 2.5400 2 3.8100 1 5.0800 6.9888 6.3500 6.5475 A C E G J L M N P B D F H K 4600 02-18 eee M X Y DETAILS OF PAD #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE PAD #1 IDENTIFIER IS A MARKED FEATURE OR A NOTCHED BEVELED PAD 4 SYMBOL TOLERANCE 0.15 aaa 0.10 bbb 0.15 eee 6. THE TOTAL NUMBER OF PADS: 104 5. PRIMARY DATUM -Z- IS SEATING PLANE LAND DESIGNATION PER JESD MO-222, SPP-010 3 2. ALL DIMENSIONS ARE IN MILLIMETERS DETAIL B PAD 1 CORNER R 0.27 – 0.37 SUBSTRATE 4 aaa Z NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994 DETAIL B MOLD CAP 2.72 – 2.92 (Reference LTM DWG # 05-05-1800) Z PADS SEE NOTES T 3 2.45 – 2.55 bbb Z LGA Package 104-Lead (15mm × 15mm) TOP VIEW 15 BSC X 15 BSC Y aaa Z LTM4600HV PACKAGE DESCRIPTIO 4600hvfc 21 U LTM4600HV U PACKAGE DESCRIPTIO Pin Assignment Tables (Arranged by Pin Number) PIN NAME A1 A2 A3 VIN A4 A5 VIN A6 A7 VIN A8 A9 VIN A10 A11 VIN A12 A13 VIN A14 A15 fADJ A16 A17 SVIN A18 A19 EXTVCC A20 A21 VOSET A22 A23 - PIN NAME B1 VIN B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 B13 B14 B15 B16 B17 B18 B19 B20 B21 B22 B23 COMP PIN NAME C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 VIN C11 C12 VIN C13 C14 VIN C15 C16 C17 C18 C19 C20 C21 C22 C23 - PIN NAME D1 VIN D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D16 D17 D18 D19 D20 D21 D22 D23 SGND PIN NAME E1 E2 E3 E4 E5 E6 E7 E8 E9 E10 VIN E11 E12 VIN E13 E14 VIN E15 E16 E17 E18 E19 E20 E21 E22 E23 - PIN NAME F1 VIN F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 RUN/SS PIN NAME G1 PGND G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 FCB PIN NAME H1 H2 H3 H4 H5 H6 H7 PGND H8 H9 PGND H10 H11 PGND H12 H13 PGND H14 H15 PGND H16 H17 PGND H18 H19 H20 H21 H22 H23 - PIN NAME J1 PGND J2 J3 J4 J5 J6 J7 J8 J9 J10 J11 J12 J13 J14 J15 J16 J17 J18 J19 J20 J21 J22 J23 PGOOD PIN NAME K1 K2 K3 K4 K5 K6 K7 PGND K8 K9 PGND K10 K11 PGND K12 K13 PGND K14 K15 PGND K16 K17 PGND K18 K19 K20 K21 K22 K23 - PIN NAME L1 L2 PGND L3 L4 PGND L5 L6 PGND L7 L8 PGND L9 L10 PGND L11 L12 PGND L13 L14 PGND L15 L16 PGND L17 L18 PGND L19 L20 PGND L21 L22 PGND L23 - PIN NAME M1 M2 PGND M3 M4 PGND M5 M6 PGND M7 M8 PGND M9 M10 PGND M11 M12 PGND M13 M14 PGND M15 M16 PGND M17 M18 PGND M19 M20 PGND M21 M22 PGND M23 - PIN NAME N1 N2 PGND N3 N4 PGND N5 N6 PGND N7 N8 PGND N9 N10 PGND N11 N12 PGND N13 N14 PGND N15 N16 PGND N17 N18 PGND N19 N20 PGND N21 N22 PGND N23 - PIN NAME P1 P2 VOUT P3 P4 VOUT P5 P6 VOUT P7 P8 VOUT P9 P10 VOUT P11 P12 VOUT P13 P14 VOUT P15 P16 VOUT P17 P18 VOUT P19 P20 VOUT P21 P22 VOUT P23 - PIN NAME R1 R2 VOUT R3 R4 VOUT R5 R6 VOUT R7 R8 VOUT R9 R10 VOUT R11 R12 VOUT R13 R14 VOUT R15 R16 VOUT R17 R18 VOUT R19 R20 VOUT R21 R22 VOUT R23 - PIN NAME T1 T2 VOUT T3 T4 VOUT T5 T6 VOUT T7 T8 VOUT T9 T10 VOUT T11 T12 VOUT T13 T14 VOUT T15 T16 VOUT T17 T18 VOUT T19 T20 VOUT T21 T22 VOUT T23 4600hvfc 22 LTM4600HV U PACKAGE DESCRIPTIO Pin Assignment Tables (Arranged by Pin Number) PIN NAME PIN NAME G1 PGND H7 H9 H11 H13 H15 H17 PGND PGND PGND PGND PGND PGND J1 PGND K7 K9 K11 K13 K15 K17 PGND PGND PGND PGND PGND PGND L2 L4 L6 L8 L10 L12 L14 L16 L18 L20 L22 PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND M2 M4 M6 M8 M10 M12 M14 M16 M18 M20 M22 PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND N2 N4 N6 N8 N10 N12 N14 N16 N18 N20 N22 PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND P2 P4 P6 P8 P10 P12 P14 P16 P18 P20 P22 VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT R2 R4 R6 R8 R10 R12 R14 R16 R18 R20 R22 VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT T2 T4 T6 T8 T10 T12 T14 T16 T18 T20 T22 VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT PIN NAME A3 A5 A7 A9 A11 A13 VIN VIN VIN VIN VIN VIN B1 VIN C10 C12 C14 VIN VIN VIN D1 VIN E10 E12 E14 VIN VIN VIN F1 VIN PIN NAME A15 fADJ A17 SVIN A19 EXTVCC A21 VOSET B23 COMP D23 SGND F23 RUN/SS G23 FCB J23 PGOOD 4600hvfc 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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 23 LTM4600HV U TYPICAL APPLICATIO 1.8V, 10A Regulator 4.5V TO 22V C2 10μF 35V C1 10μF 35V VIN C5 100pF fADJ 1.8V AT 10A EXTVCC VOUT FCB VOSET R1 100k LTM4600HV RUN C3 22μF x3 + C4 470μF 4V SVIN PGOOD COMP SGND PGND 4600hv TA04 PGOOD R2 49.9k 1% C1, C2: TAIYO YUDEN, GDK316BJ106ML C3: TAIYO YUDEN, JMK316BJ226ML-T501 C4: SANYO POSCAP, 4TPE470MCL 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/ Synchronizable, PolyPhase Operation to 48A, LTM4601-1 Version has no Margining and Remote Sensing Remote Sensing, Pin Compatible with the LTM4601 This product contains technology licensed from Silicon Semiconductor Corporation. 24 Linear Technology Corporation ® 4600hvfc LT 0707 REV C • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2005