LTM4600 LINER | Alldatasheet
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Technical content
LOAD CURRENT (A) EFFICIENCY (%)50 6 10
4600 TA01b
1.2VOUT 1.5VOUT 2.5VOUT 3.3VOUT 10A High Effi ciency DC/DC µModule The LTM®4600 is a complete 10A, DC/DC step down power supply. Included in the package are the switching control- ler, power FETs, inductor, and all support components. Operating over an input voltage range of 4.5V to 20V, the LTM4600 supports an output voltage range of 0.6V to 5V, set by a single resistor. This high effi ciency design delivers 10A continuous current (14A peak), needing no heat sinks or airfl ow to meet power specifi cations. Only bulk input and output capacitors are needed to fi nish the design. The low profi le 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 sacrifi cing 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 LTM4600 is packaged in a thermally enhanced, compact (15mm × 15mm) and low profi le (2.8mm) over-molded Land Grid Array (LGA) package suitable for automated assembly by standard surface mount equipment. The LTM4600 is Pb-free and RoHS compliant. ■ Telecom and Networking Equipment ■ Servers ■ Industrial Equipment ■ Point of Load Regulation ■ Complete Switch Mode Power Supply ■ Wide Input Voltage Range: 4.5V to 20V ■ 10A DC, 14A 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 ■ Pb-Free (e4) RoHS Compliant Package with Gold- Pad Finish ■ Up to 92% Effi ciency ■ Programmable Soft-Start ■ Output Overvoltage Protection ■ Optional Short-Circuit Shutdown Timer ■ Small Footprint, Low Profi le (15mm × 15mm × 2.8mm) Surface Mount LGA Package 10A µModule Power Supply with 4.5V to 20V Input APPLICATIO SU FEATURES DESCRIPTIO U TYPICAL APPLICATIO U , 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. Protected by U.S. Patents including 5481178, 6100678, 6580258, 5847554, 6304066. Effi ciency vs Load Current with 12VIN (FCB = 0) VIN CIN
4600 TA01a
4.5V TO 20V VOUT 1.5V 10ACOUT 66.5k
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. External CIN = 120µF, COUT = 200µF/Ceramic 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 FCB = 0V V IN = 5V or 12V, VOUT = 1.5V, IOUT = 0A 1.478 1.470 1.50 1.50 1.522 1.530 V V Input Specifi cations V IN(UVLO) Under Voltage Lockout Threshold I OUT = 0A 3.4 4 V IINRUSH(VIN) Input Inrush Current at Startup I OUT = 0A. VOUT = 1.5V, FCB = 0 V IN = 5V V IN = 12V 0.6 0.7 A A IQ(VIN) Input Supply Bias Current I OUT = 0A, EXTVCC Open V IN = 12V, VOUT = 1.5V, FCB = 5V V IN = 12V, VOUT = 1.5V, FCB = 0V V IN = 5V, VOUT = 1.5V, FCB = 5V V IN = 5V, VOUT = 1.5V, FCB = 0V Shutdown, RUN = 0.8V, V IN = 12V 1.2 1.0 35 75 mA mA mA mA µA I S(VIN) Input Supply Current V IN = 12V, VOUT = 1.5V, IOUT = 10A VIN = 12V, VOUT = 3.3V, IOUT = 10A VIN = 5V, VOUT = 1.5V, IOUT = 10A 1.52 3.13 3.64 A A A RUN/SS FCB PGOOD VIN PGND VOUT COMP SGND EXTVCC VOSET fADJ SVIN LGA PACKAGE 104-LEAD (15mm × 15mm × 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 LTM4600EV#PBF LTM4600IV#PBF LTM4600EV LTM4600IV Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
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 LTM4600E 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 LTM4600I is guaranteed and tested over the –40°C to 85°C temperature range. Note 3: Test assumes current derating verses temperature. 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 10 A ΔVOUT/ΔVIN Line Regulation Accuracy V OUT = 1.5V, IOUT = 0A, FCB = 0V, VIN = 4.5V to 20V
- 0.15 0.3 % ΔVOUT/ΔIOUT Load Regulation Accuracy V OUT = 1.5V, IOUT = 0A to 10A, FCB = 0V V IN = 5V V IN = 12V (Note 3) ● ±1.5 VOUT(AC) Output Ripple Voltage V IN = 12V, VOUT = 1.5V, IOUT = 0A, FCB = 0V 10 15 mV P-P fs Output Ripple Voltage Frequency V OUT = 1.5V, IOUT = 5A, FCB = 0V 800 kHz tSTART Turn-On Time V OUT = 1.5V, IOUT = 10A V IN = 12V V IN = 5V 0.5 0.7 ms ms ΔVOUTLS Voltage Drop for Dynamic Load Step V OUT = 1.5V, Load Step: 0A/µs to 5A/µs COUT = 3 • 22µF 6.3V, 470µF 4V Pos Cap, See Table 2 36 mV tSETTLE Settling Time for Dynamic Load Step Load: 10% to 90% to 10% of Full Load 25 µs IOUTPK Output Current Limit Output Voltage in Foldback V IN = 12V, VOUT = 1.5V V IN = 5V, VOUT = 1.5V A A Control Stage VOSET Voltage at VOSET Pin I OUT = 0A, VOUT = 1.5V ● 0.591 0.594 0.6 0.6 0.609 0.606 V V VRUN/SS RUN ON/OFF Threshold 0.8 1.5 2 V IRUN(C)/SS Soft-Start Charging Current V RUN/SS = 0V –0.5 –1.2 –3 µA IRUN(D)/SS Soft-Start Discharging Current V RUN/SS = 4V 0.8 1.8 3 µA VIN – SVIN EXTVCC = 0V, FCB = 0V 100 mV IEXTVCC Current into EXTVCC Pin EXTV CC = 5V, FCB = 0V, VOUT = 1.5V, IOUT = 0A 16 mA RFBHI Resistor Between VOUT and FB Pins 100 k Ω VFCB Forced Continuous Threshold 0.57 0.6 0.63 V IFCB Forced Continuous Pin Current V FCB = 0.6V –1 –2 µA PGOOD Output ΔV OSETH PGOOD Upper Threshold V OSET Rising 7.5 10 12.5 % ΔVOSETL PGOOD Lower Threshold V OSET Falling –7.5 –10 –12.5 % ΔVOSET(HYS) PGOOD Hysteresis V OSET Returning 2 % VPGL PGOOD Low Voltage I PGOOD = 5mA 0.15 0.4 V 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.
LOAD CURRENT (A) EFFICIENCY (%)50 6 10
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0.6VOUT 1.2VOUT 1.5VOUT 2.5VOUT 3.3VOUT Effi ciency vs Load Current with 5VIN (FCB = 0) TYPICAL PERFOR A CE CHARACTERISTICSUW LOAD CURRENT (A) 100 61 0
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EFFICIENCY (%) 0.6VOUT 1.2VOUT 1.5VOUT 2.5VOUT Effi ciency vs Load Current with 12VIN (FCB = 0) Effi ciency vs Load Current with 18V IN (FCB = 0) LOAD CURRENT (A) EFFICIENCY (%) 6 10
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1.5VOUT 1.8VOUT 2.5VOUT 3.3VOUT Effi ciency vs Load Current with Different FCB Settings LOAD CURRENT (A)
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EFFICIENCY (%) 0.1 101 FCB = GND FCB > 0.7V VIN = 12V VOUT = 1.5V 1.2V Transient Response 1.5V Transient Response 1.8V Transient Response 2.5V Transient Res ponse 3.3V Transient Res ponse 25µs/DIV 4600 G05 1.2V AT 5A/µs LOAD STEP COUT = 3 • 22µF 6.3V CERAMICS 470µF 4V SANYO POS CAP C3 = 100pF 25µs/DIV
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1.5V AT 5A/µs LOAD STEP COUT = 3 • 22µF 6.3V CERAMICS 470µF 4V SANYO POS CAP C3 = 100pF 25µs/DIV
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1.8V AT 5A/µs LOAD STEP COUT = 3 • 22µF 6.3V CERAMICS 470µF 4V SANYO POS CAP C3 = 100pF 25µs/DIV
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2.5V AT 5A/µs LOAD STEP COUT = 3 • 22µF 6.3V CERAMICS 470µF 4V SANYO POS CAP C3 = 100pF 25µs/DIV
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3.3V AT 5A/µs LOAD STEP COUT = 3 • 22µF 6.3V CERAMICS 470µF 4V SANYO POS CAP C3 = 100pF VOUT = 50mV/DIV IOUT = 5A/DIV (See Figure 17 for all curves)
VIN (V) 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 51 5
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VOUT (V) 3.3V 2.5V 1.8V 1.5V 1.2V fADJ = OPEN SEE FREQUENCY ADJUSTMENT DISCUSSION FOR 12VIN TO 5VOUT AND 5VIN TO 3.3VOUT CONVERSION 0.6V TYPICAL PERFOR A CE CHARACTERISTICSUW Start-Up, IOUT = 0A Start-Up, IOUT = 10A (Resistive Load) Short-Circuit Protection, IOUT = 0A Short-Circuit Protection, IOUT = 10A 200µs/DIV 4600 G10 VIN = 12V VOUT = 1.5V COUT = 200µF NO EXTERNAL SOFT-START CAPACITOR VOUT (0.5V/DIV) IIN (0.5A/DIV) 200µs/DIV 4600 G11 VIN = 12V VOUT = 1.5V COUT = 200µF NO EXTERNAL SOFT-START CAPACITOR VOUT (0.5V/DIV) IIN (0.5A/DIV) 20µs/DIV 4600 G12 VIN = 12V VOUT = 1.5V COUT = 2× 200µF/X5R NO EXTERNAL SOFT-START CAPACITOR VOUT (0.5V/DIV) IIN (0.2A/DIV) 20µs/DIV 4600 G13 VIN = 12V VOUT = 1.5V COUT = 2× 200µF/X5R NO EXTERNAL SOFT-START CAPACITOR VOUT (0.5V/DIV) IIN (0.5A/DIV) VIN to VOUT Stepdown Ratio (See Figure 17 for all curves)
VIN (Bank 1): Power Input Pins. Apply input voltage between these pins and GND pins. Recommend placing input decoupling capacitance directly between V IN pins and GND pins. fADJ (Pin A15): A 110k resistor from VIN to this pin sets the one-shot timer current, thereby setting the switching frequency. The LTM4600 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. SV IN (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 EXTV CC voltage should never be higher than VIN. VOSET (Pin A21): The Negative Input of The Error Amplifi er. Internally, this pin is connected to VOUT with a 100k precision resistor. Different output voltages can be programmed with additional resistors between the V OSET and SGND pins. COMP (Pin B23): Current Control Threshold and Error Amplifi er 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). SGND (Pin D23): Signal Ground Pin. All small-signal components should connect to this ground, which in turn connects to PGND at one point. 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 V IN pin. This pullup resistor must supply a minimum 5µA pull up current. 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 effi ciency operation at light loads. There is an internal 4.75K resistor between the FCB and SGND pins. PGOOD (Pin J23): Output Voltage Power Good Indicator. When the output voltage is within 10% of the nominal voltage, the PWRGD is open drain output. Otherwise, this pin is pulled to ground. PGND (Bank 2): Power ground pins for both input and output returns. V OUT (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. (See Package Description for Pin Assignment) E C A RUN/SS FCB PGOOD V IN BANK 1 PGND BANK 2 VOUT BANK 3 COMP SGND EXTVCC VOSET fADJ SVIN TOP VIEW 11 13 10 12 15 17 14 16 19 21 18 20 22 94 95 96 97 98 99 100 101 102 103 104 19181716765432 84 85 86 87 88 89 90 91 74 75 76 77 78 79 80 63 64 65 66 67 68 69 52 53 54 55 56 57 58 42 43 44 45 46 47 11109 13 14 15 26 27 28 29 30 31 33 34 35 36 37 38 1 23 B D F G H J L M N P R T K
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T A = 25°C, VIN = 12V. Use Figure 1 confi guration. Figure 1. Simplifi ed LTM4600 Block Diagram
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µModule Description The LTM4600 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 0.6V DC to 5.0VDC, not to exceed 80% of the input voltage. The input voltage range is 4.5V to 20V. A simplifi ed block diagram is shown in Figure 1 and the typical application schematic is shown in Figure 17. The LTM4600 contains an integrated LTC constant on-time current-mode regulator, ultra-low R DS(ON) FETs with fast switching speed and integrated Schottky diode. The typical switching frequency is 800kHz at full load. With current mode control and internal feedback loop compensation, the LTM4600 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 (X5R or X7R). Current mode control provides cycle-by-cycle fast current limit. In addition, foldback current limiting is provided in an over-current condition while V FB drops. Also, the LTM4600 has defeatable short circuit latch off. Internal overvolt- age 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 cur- rent mode by default to achieve minimum output voltage ripple. It can be programmed to operate in discontinuous current mode for improved light load effi ciency 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 V IN 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 ap- plied on the EXTV CC pin, the internal regulator is turned off, and an internal switch connects EXTV CC 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 EXTV CC pin is 6V. The EXTVCC voltage should never be higher than the VIN voltage. Also EXTVCC must be sequenced after VIN.
APPLICATIO S I FOR ATIOWU UU down when Q DOWN is on and Q UP 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: () ( % ) () .RR V M RR k VSET UP O SET UP 100 06+ +Ω = RV M Rk R VSET O SET DOWN ( – % ) () .1 100 06+Ω = Input Capacitors The LTM4600 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 mod- ule. In Figure 20, the bulk input capacitor C IN 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 V V O IN Without considering the inductor current ripple, the RMS current of the input capacitor can be estimated as: I I DDCIN RMS OM A X % ( )=− η 1 In the above equation, η% is the estimated effi ciency 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. In Figure 16, the input capacitors are used as high fre- quency input decoupling capacitors. In a typical 10A output application, 1-2 pieces of very low ESR X5R or X7R, 10µF ceramic capacitors are recommended. This decoupling capacitor should be placed directly adjacent The typical LTM4600 application circuit is shown in Figure 17. External component selection is primarily determined by the maximum load current and output voltage. Output Voltage Programming and Margining The PWM controller of the LTM4600 has an internal 0.6V±1% reference voltage. As shown in the block diagram, a 100k/0.5% internal feedback resistor connects V OUT and FB pins. Adding a resistor RSET from VOSET pin to SGND pin programs the output voltage: VV kR RO SET SET = +06 100. Table 1 shows the standard vaules of 1% R SET resistor for typical output voltages: Table 1. RSET VO 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/protec- tion functionality of the board and improve the system reliability. Figure 2 shows how to implement margining function with the LTM4600. In addition to the feedback resistor R SET, several external components are added. Turn off both transistor Q UP and Q DOWN to disable the margining. When QUP is on and QDOWN is off, the output voltage is margined up. The output voltage is margined Figure 2. PGND SGND
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APPLICATIO S I FOR ATIOWU UU the module input pins in the PCB layout to minimize the trace inductance and high frequency AC noise. Output Capacitors The LTM4600 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. C OUT 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 suffi cient stability margin for all ceramic capacitors applications. Additional output fi ltering 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 capaci- tance matrix for each output voltage Droop, peak to peak deviation and recovery time during a 5A/µs transient with a specifi c output capacitance. Fault Conditions: Current Limit and Over current Foldback The LTM4600 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 over load condi- tion, the LTM4600 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 LTM4600 as well as a timer for soft-start and over-cur- rent latchoff. Pulling the RUN/SS pin below 0.8V puts the LTM4600 into a low quiescent current shutdown (I Q ≤ 75µA). Releasing the pin allows an internal 1.2µA cur- rent source to charge up the timing capacitor CSS. Inside LTM4600, 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: t V A Cp FDELAY SS EXT= µ +15 12 1000. . ( ) _ When the voltage on RUN/SS pin reaches 1.5V, the LTM4600 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. V IN to VOUT Stepdown Ratios There are restrictions in the maximum V IN 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 “V IN to V OUT Stepdown Ratio”. Note that additional thermal de-rating may apply. See the Thermal Considerations and Output Current De- Rating sections of this data sheet.
Table 2. Output Voltage Response Verses Component Matrix (Refer to Figure 17)
down to ground in order to restart operation. Generally 0.1µF is more than suffi cient.
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Figure 4. Defeat Short-Circuit Latchoff with a Pull-Up Figure 3. RUN/SS Pin Voltage During Startup and
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Figure 5. This function allows the LTM4600 to be turned sequence of the output voltage. Figure 5. Enable Circuit with External Logic
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Figure 6. Output Voltage Tracking with the LTC2923 Controller
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power supply tracking controller such as the LTC2923. values. See the LTC2923 data sheet for more details. supply that powers the control circuitry and FET drivers.
- EXTVCC grounded. Internal 5V LDO is always powered
from the internal 5V regulator.
- EXTVCC connected to an external supply. Internal LDO
MOSFET remains on when the inductor current reverses. provides minimum output voltage ripple.
at the junction of the device. provided to protect each unit from catastrophic failure. tion loss is minimized and light load effi cient is improved. output voltage ripple increases at light load. sharing among modules to balance the thermal stress. where N is the number of LTM4600s in parallel. Figure 7. Parallel Two µModules with Load Sharing
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OPTI-LOOP is a trademark of Linear Technology Corporation.
Figure 14. No Heatsink Figure 15. BGA Heatsink
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400 LFM
200 LFM
0 LFM
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Figure 8. Power Loss vs Load Current Figure 9. No Heatsink Figure 10. BGA Heatsink Figure 11. No Heatsink Figure 12. BGA Heatsink Figure 13. Power Loss vs Load Current
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Figure 16. Recommended PCB Layout
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- 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
- 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 via directly on pad
- Use a separated SGND ground copper area for compo- nents connected to signal pins. Connect the SGND to PGND underneath the unit Figure 16 gives a good example of the recommended layout. Frequency Adjustment The LTM4600 is designed to typically operate at 800kHz across most input and output conditions. The f ADJ pin is typically left open or decoupled with an optional 1000pf capacitor. The switching frequency has been optimized for maintaining constant output ripple noise over the operating ranges. The switching frequency will increase up to typically 1.2MHz for 5V and 3.3V outputs to limit increase output ripple noise. The switching frequency can be adjusted lower to accommodate high duty cycle requirements like 5V to 3.3V, and 12V to 5V. There are limitations to input voltage range for the higher duty cycle designs that limit the internal inductor ripple current so that the inductor will not saturate at higher load current. Examples: LTM4600 minimum on-time = 100ns LTM4600 minimum off-time = 400ns Equations for setting frequency: I ON = VIN – 0.7V/110k; for 12V input, ION = 103µA frequency = (I ON/[2.4V • 10pF]) • DC; DC = duty cycle, duty cycle is (VOUT/VIN) t = t ON + t OFF, t ON = on-time, t OFF = off-time of the switching period; t = 1/frequency tOFF must be greater than 400ns, or t – tON > 400ns. t ON = DC • t 1MHz frequency or 1µs period is chosen for 12V to 5V. t ON = 0.41 • 1µs ≅ 410ns t OFF = 1µs – 410ns ≅ 590ns tON and tOFF are above the minimums with adquate 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 f ADJ 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 f ADJ. The
inductor ripple current gets too high above 16V, and the 400ns minimum off-time is limited below 9V. Equations for setting frequency: I ON = VIN – 0.7V/110k; for 5V input, ION = 39µA frequency = (I ON/[2.4V • 10pF]) • DC; DC = duty cycle, duty cycle is (VOUT/VIN) t = t ON + t OFF, t ON = on-time, t OFF = off-time of the switching period; t = 1/frequency tOFF must be greater than 400ns, or t – tON > 400ns. t ON = DC • t ~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. t ON = 0.66 • 2.22µs ≅ 1.46ns t OFF = 2µs – 1.32ns ≅ 760ns tON and tOFF are above the minimums with adquate 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 I ON 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 f ADJ. The inductor ripple current gets too high above 7V, and the 400ns minimum off-time is limited below 4.5V. APPLICATIO S I FOR ATIOWU UU
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22.1k 30.1kEXTVCC RUN/SS COMP FCB VOUT 5V TO 3.3V AT 8A WITH fADJ = 30.1k C1, C3: TDK C3216X5R1E106MT C2: TAIYO YUDEN, JMK316BJ226ML C4: SANYO POS CAP, 6TPE330MIL PGOOD VOSET SVIN PGNDSGND 4.5V TO 7V 3.3V AT 8A 10µF 25V 10µF 25V 330µF 6.3V 22µF 100pFVIN LTM4600EV fADJ RUN/SOFT-START OPEN DRAIN EFFICIENCY = 93%
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13.7k 15kEXTVCC RUN/SS COMP FCB VOUT 12V TO 5V AT 8A WITH fADJ = 15k C1, C3: TDK C3216X5R1E106MT C2: TAIYO YUDEN, JMK316BJ226ML C4: SANYO POS CAP, 6TPE330MIL PGOOD VOSET SVIN PGNDSGND 9V TO 16V 5V AT 8A EFFICIENCY = 93% 10µF 25V 10µF 25V 330µF 6.3V 22µF 100pFVIN LTM4600EV fADJ RUN/SOFT-START OPEN DRAIN 5V to 3.3V at 8A 12V to 5V at 8A
Figure 17. Typical Application, 5V to 20V Input, 0.6V to 5V Output, 10A Max
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4600 F20
4600 TA02
15.8k EXTVCC RUN COMP FCB VOUT VOUT = 0.6V ([100k/N] + RSET)/RSET WHERE N = 2 C1, C3, C7, C8: TDK C3216X5R1E106MT C2, C9: TAIYO YUDEN, JMK316BJ226ML-T501 C5, C10: SANYO POS CAP, 4TPE470MCL PGOOD VOSET SVIN PGNDSGND 2.5V AT 20A 4.5V TO 20V 2.5V 2.5V 10µF 25V 10µF 25V C10 470µF 22µF VIN LTM4600 fADJ 100k EXTVCC RUN COMP FCB VOUT PGOOD VOSET SVIN PGNDSGND 10µF 25V RUN/SOFT-START 10µF 25V 220pF 470µF 22µF VIN LTM4600 fADJ TOTAL LOAD INDIVIDUAL SHARE 5 10 15 20
4600 TA03
2.5VOUT 20AMAX Current Sharing Between Two LTM4600 Modules Parallel Operation and Load Sharing
104-Lead (15mm × 15mm) (Reference LTM DWG # 05-05-1800) 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: 104 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 SYMBOL aaa bbb eee TOLERANCE 0.15 0.10 0.15 2.72 – 2.92 DETAIL B DETAIL B SUBSTRATE MOLD CAP 0.27 – 0.37 2.45 – 2.55 bbb Z Z BSC TOP VIEW BSC
4 PAD 1
X Y aaa Z aaa Z 13.97 BSC 12.70 BSC 0.11 – 0.27 13.93 BSC 11 13 10 12 15 17 14 16 19 21 18 20 22 4600 02-18 BOTTOM VIEW C(0.30) PAD 1 PADS SEE NOTES 94 95 96 97 98 99 100 101 102 103 104 19181716765432 84 85 86 87 88 89 90 91 74 75 76 77 78 79 80 63 64 65 66 67 68 69 52 53 54 55 56 57 58 42 43 44 45 46 47 11109 13 14 15 26 27 28 29 30 31 33 34 35 36 37 38 M YXeee1 SUGGESTED SOLDER PAD LAYOUT TOP VIEW 94 95 96 97 98 99 100 101 102 103 104 19181716765432 84 85 86 87 88 89 90 91 74 75 76 77 78 79 80 63 64 65 66 67 68 69 52 53 54 55 56 57 58 42 43 44 45 46 47 11109 13 14 15 26 27 28 29 30 31 33 34 35 36 37 38 0.0000 1.2700 2.5400 0.3175 0.3175 4.4450 5.7150 6.9850 1.4675 5.7158 6.9421 4.4458 6.3500 6.3500 3.8100 3.8100 1.2700 0.3175 0.3175 0.0000 1.2700 3.1758 1.9058 0.6358 0.0000 0.6342 1.9042 3.1742 4.4442 5.7142 6.9865 2.7375 4.0075 5.2775 6.5475 6.9888 1.0900 2.3600 4.4950 5.7650 5.0800 5.0800 2.5400 2.5400 A B C D E F G H J L M N P R T K
PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME A1 - B1 V IN C1 - D1 V IN E1 - F1 V IN G1 PGND H1 - A2 - B2 - C2 - D2 - E2 - F2 - G2 - H2 - A3 V IN B3 - C3 - D3 - E3 - F3 - G3 - H3 - A4 - B4 - C4 - D4 - E4 - F4 - G4 - H4 - A5 V IN B5 - C5 - D5 - E5 - F5 - G5 - H5 - A6 - B6 - C6 - D6 - E6 - F6 - G6 - H6 - A7 V IN B7 - C7 - D7 - E7 - F7 - G7 - H7 PGND A8 - B8 - C8 - D8 - E8 - F8 - G8 - H8 - A9 V IN B9 - C9 - D9 - E9 - F9 - G9 - H9 PGND A10 - B10 - C10 V IN D10 - E10 V IN F10 - G10 - H10 - A11 V IN B11 - C11 - D11 - E11 - F11 - G11 - H11 PGND A12 - B12 - C12 V IN D12 - E12 V IN F12 - G12 - H12 - A13 V IN B13 - C13 - D13 - E13 - F13 - G13 - H13 PGND A14 - B14 - C14 V IN D14 - E14 V IN F14 - G14 - H14 - A15 f ADJ B15 - C15 - D15 - E15 - F15 - G15 - H15 PGND A16 - B16 - C16 - D16 - E16 - F16 - G16 - H16 - A17 SV IN B17 - C17 - D17 - E17 - F17 - G17 - H17 PGND A18 - B18 - C18 - D18 - E18 - F18 - G18 - H18 - A19 EXTV CC B19 - C19 - D19 - E19 - F19 - G19 - H19 - A20 - B20 - C20 - D20 - E20 - F20 - G20 - H20 - A21 V OSET B21 - C21 - D21 - E21 - F21 - G21 - H21 - A22 - B22 - C22 - D22 - E22 - F22 - G22 - H22 - A23 - B23 COMP C23 - D23 SGND E23 - F23 RUN/SS G23 FCB H23 - PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME J1 PGND K1 - L1 - M1 - N1 - P1 - R1 - T1 - J2 - K2 - L2 PGND M2 PGND N2 PGND P2 V OUT R2 V OUT T2 V OUT J3 - K3 - L3 - M3 - N3 - P3 - R3 - T3 - J4 - K4 - L4 PGND M4 PGND N4 PGND P4 V OUT R4 V OUT T4 V OUT J5 - K5 - L5 - M5 - N5 - P5 - R5 - T5 - J6 - K6 - L6 PGND M6 PGND N6 PGND P6 V OUT R6 V OUT T6 V OUT J7 - K7 PGND L7 - M7 - N7 - P7 - R7 - T7 - J8 - K8 L8 PGND M8 PGND N8 PGND P8 V OUT R8 V OUT T8 V OUT J9 - K9 PGND L9 - M9 - N9 - P9 - R9 - T9 - J10 - K10 L10 PGND M10 PGND N10 PGND P10 V OUT R10 V OUT T10 V OUT J11 - K11 PGND L11 - M11 - N11 - P11 - R11 - T11 - J12 - K12 - L12 PGND M12 PGND N12 PGND P12 V OUT R12 V OUT T12 V OUT J13 - K13 PGND L13 - M13 - N13 - P13 - R13 - T13 - J14 - K14 - L14 PGND M14 PGND N14 PGND P14 V OUT R14 V OUT T14 V OUT J15 - K15 PGND L15 - M15 - N15 - P15 - R15 - T15 - J16 - K16 - L16 PGND M16 PGND N16 PGND P16 V OUT R16 V OUT T16 V OUT J17 - K17 PGND L17 - M17 - N17 - P17 - R17 - T17 - J18 - K18 - L18 PGND M18 PGND N18 PGND P18 V OUT R18 V OUT T18 V OUT J19 - K19 - L19 - M19 - N19 - P19 - R19 - T19 - J20 - K20 - L20 PGND M20 PGND N20 PGND P20 V OUT R20 V OUT T20 V OUT J21 - K21 - L21 - M21 - N21 - P21 - R21 - T21 - J22 - K22 - L22 PGND M22 PGND N22 PGND P22 V OUT R22 V OUT T22 V OUT J23 PGOOD K23 - L23 - M23 - N23 - P23 - R23 - T23 - PACKAGE DESCRIPTIO U Pin Assignment Tables (Arranged by Pin Number)
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. PACKAGE DESCRIPTIO U PIN NAME G1 PGND H11 H13 H15 H17 PGND PGND PGND PGND PGND PGND J1 PGND K11 K13 K15 K17 PGND PGND PGND PGND PGND PGND L10 L12 L14 L16 L18 L20 L22 PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND M10 M12 M14 M16 M18 M20 M22 PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND N10 N12 N14 N16 N18 N20 N22 PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PGND PIN NAME P10 P12 P14 P16 P18 P20 P22 V OUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT R10 R12 R14 R16 R18 R20 R22 V OUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT T10 T12 T14 T16 T18 T20 T22 V OUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT PIN NAME A11 A13 V IN VIN VIN VIN VIN VIN B1 V IN C10 C12 C14 V IN VIN VIN D1 V IN E10 E12 E14 V IN VIN VIN F1 V IN PIN NAME A15 f ADJ A17 SV IN A19 EXTV CC A21 V OSET B23 COMP D23 SGND F23 RUN/SS G23 FCB J23 PGOOD Pin Assignment Tables (Arranged by Pin Number)
© LINEAR TECHNOLOGY CORPORATION 2005 LT 0206 REV A PRINTED IN USA Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com TYPICAL APPLICATIO U 1.8V, 10A Regulator
4600 TA04
C1, C2: TDK C3216X5R1E106MT C3: TAIYO YUDEN, JMK316BJ226ML-T501 C4: SANYO POS CAP, 4TPE470MCL 1.8V AT 10A 4.5V AT 20V 100k EXTVCC RUN COMP FCB VOUT PGOOD VOSET SVIN PGNDSGND 10µF 25V 10µF 25V 100pF 470µF PGOOD 22µF VIN LTM4600 fADJ 49.9k This product contains technology licensed from Silicon Semiconductor Corporation. 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