LTM4604

LTM4604 Low Voltage, 4A DC/DC µModuleTM with Tracking FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTION The LTM®4604 is a complete 4A switch mode DC/DC power supply. Included in the package are the switching controller, power FETs, inductor and all support components. Operating over an input voltage range of 2.375V to 5.5V, the LTM4604 supports an output voltage range of 0.8V to 5V, set by a single resistor. This high efficiency design delivers up to 4A continuous current (5A peak). Only bulk output capacitors are needed to complete the design. The low profile package (2.3mm) enables utilization of unused space on the bottom of PC boards for high density point of load regulation. High switching frequency and a current mode architecture enable a very fast transient response to line and load changes without sacrificing stability. The device supports output voltage tracking for supply rail sequencing. Fault protection features include foldback current protection, thermal shutdown and a programmable soft-start function. The LTM4604 is offered in a space saving and thermally enhanced 15mm × 9mm × 2.3mm LGA package and is Pb free and RoHS compliant. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. μModule and UltraFast are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Complete Standalone Power Supply Wide Input Voltage Range: 2.375V to 5.5V 4A DC, 5A Peak Output Current 0.8V to 5V Output Output Voltage Tracking ±2% Total DC Error UltraFastTM Transient Response Power Good Indicator Current Mode Control Current Foldback Protection, Parallel/Current Sharing Up to 95% Efficiency Programmable Soft-Start Micropower Shutdown: IQ ≤ 7μA Overtemperature Protection Small and Very Low Profile Package: 15mm × 9mm × 2.3mm LGA APPLICATIONS ■ ■ ■ ■ ■ Telecom and Networking Equipment Servers Storage Cards ATCA Cards Industrial Equipment TYPICAL APPLICATION Efficiency vs Output Current 3.3V to 2.5V/4A μModule Regulator VIN 3.3V 10μF 6.3V VIN PGOOD COMP GND VOUT FB VIN 2.37k LTM4604 RUN/SS TRACK VOUT 2.5V 4A 22μF 6.3V ×2 4604 TA01a 100 95 90 EFFICIENCY (%) 85 80 75 70 65 0 1 2 3 OUTPUT CURRENT (A) "$" / VIN = 3.3V VOUT = 2.5V 4 4604f 1 LTM4604 ABSOLUTE MAXIMUM RATINGS (Note 1) PIN CONFIGURATION TOP VIEW TRACK A 1 2 3 4 5 6 7 8 9 10 11 GND VOUT LGA PACKAGE 66-PIN (15mm ´ 9mm ´ 2.3mm) TJMAX = 125°C, θJA = 25°C/W, WEIGHT = 0.86g SW RUN/ SS GND B VIN COMP FB C D E PGOOD F G VIN, PGOOD ................................................. –0.3V to 6V COMP, RUN/SS, FB, TRACK .........................–0.3V to VIN SW, VOUT........................................–0.3V to (VIN + 0.3V) Operating Temperature Range (Note 2) ... –40°C to 85°C Junction Temperature ........................................... 125°C Storage Temperature Range................... –55°C to 125°C ORDER INFORMATION LEAD FREE FINISH LTM4604EV#PBF LTM4604IV#PBF TRAY LTM4604EV#PBF LTM4604IV#PBF PART MARKING* LTM4604V LTM4604V PACKAGE DESCRIPTION 15mm × 9mm × 2.3mm LGA 15mm × 9mm × 2.3mm LGA TEMPERATURE RANGE –40°C to 85°C –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. 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/ This product is only offered in trays. For more information go to: http://linear.com/packaging/ ELECTRICAL CHARACTERISTICS SYMBOL VIN(DC) VOUT(DC) The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 5V unless otherwise noted. See Figure 15. PARAMETER CONDITIONS Input DC Voltage Output Voltage, Total Variation CIN = 10μF × 1, COUT = 22μF ×3, RFB = 5.69k 0.5% with Line and Load VIN = 2.375V to 5.5V, IOUT = 0A to 4A, 0°C ≤ TA ≤ 85°C VIN = 2.375V to 5.5V, IOUT = 0A to 4A IOUT = 0A IOUT = 0A, CIN = 10μF, COUT = 22μF ×3, RUN/SS = 0.01μF, VOUT = 1.5V VIN = 3.3V VIN = 5V VIN = 3.3V, VOUT = 1.5V, No Switching VIN = 3.3V, VOUT = 1.5V, Switching Continuous VIN = 5V, VOUT = 1.5V, No Switching VIN = 5V, VOUT = 1.5V, Switching Continuous Shutdown, RUN = 0, VIN = 5V ● MIN 2.375 1.478 1.470 1.75 TYP MAX 5.5 1.522 1.522 2.3 UNITS V V V V ● 1.5 1.5 2 Input Specifications Undervoltage Lockout VIN(UVLO) Threshold Peak Input Inrush Current at IINRUSH(VIN) Start-Up IQ(VIN NOLOAD) Input Supply Bias Current 0.7 0.7 60 28 100 35 7 A A μA mA μA mA μA 4604f 2 LTM4604 ELECTRICAL CHARACTERISTICS SYMBOL IS(VIN) PARAMETER Input Supply Current The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 5V unless otherwise noted. See Figure 15. CONDITIONS VIN = 2.5V, VOUT = 1.5V, IOUT = 4A VIN = 3.3V, VOUT = 1.5V, IOUT = 4A VIN = 5V, VOUT = 1.5V, IOUT = 4A VIN = 3.3V, VOUT = 1.5V MIN TYP 2.9 2.2 1.45 MAX UNITS A A A A Output Specifications IOUT(DC) Output Continuous Current Range (See Output Current Derating Curves for Different VIN, VOUT and TA) ΔVOUT(LINE) Line Regulation Accuracy VOUT ΔVOUT(LOAD) VOUT VOUT(AC) fS ΔVOUT(START) Output Ripple Voltage Load Regulation Accuracy 4 VOUT = 1.5V, VIN from 2.375V to 5.5V, IOUT = 0A VOUT = 1.5V, 0A to 4A VIN = 3.3V VIN = 5V IOUT = 0A, COUT = 22μF/X5R/Ceramic ×3 VIN = 3.3V, VOUT = 1.5V VIN = 5V, VOUT = 1.5V IOUT = 4A, VIN = 5V, VOUT = 1.5V COUT = 22μF ×3, VOUT = 1.5V, RUN/SS = 10nF, IOUT = 0A VIN = 3.3V VIN = 5V COUT = 22μF ×3, VOUT = 1.5V, IOUT = 1A Resistive Load, TRACK = VIN and RUN/SS = Float VIN = 3.3V VIN = 5V Load: 0% to 50% to 0% of Full Load, COUT = 22μF ×3 Ceramic VIN = 5V, VOUT = 1.5V Load: 0% to 50% to 0% of Full Load VIN = 5V, VOUT = 1.5V COUT = 22μF ×3 VIN = 3.3V, VOUT = 1.5V VIN = 5V, VOUT = 1.5V IOUT = 0A, VOUT = 1.5V, 0°C ≤ TA ≤ 85°C IOUT = 0A, VOUT = 1.5V ● 0.1 0.2 % ● ● 0.3 0.3 10 12 1.25 0.6 0.6 % % mVP-P mVP-P MHz Output Ripple Voltage Frequency Turn-On Overshoot 20 20 mV mV tSTART Turn-on Time 1.5 1.0 ms ms ΔVOUT(LS) tSETTLE IOUT(PK) Control Section VFB IFB VRUN ITRACK VTRACK(OFFSET) VTRACK(RANGE) RFBHI PGOOD ΔVPGOOD RPGOOD Peak Deviation for Dynamic Load Step Settling Time for Dynamic Load Step Output Current Limit 25 10 8 8 0.792 0.788 0.5 0.8 0.8 0.2 0.65 0.2 30 4.99 0.808 0.812 0.8 mV μs A A V V μA V μA mV V kΩ Voltage at FB Pin ● RUN Pin On/Off Threshold TRACK Pin Current Offset Voltage Tracking Input Range Resistor Between VOUT and FB Pins PGOOD Range PGOOD Resistance TRACK = 0.4V 0 4.975 0.8 5.025 Open-Drain Pull-Down ±7.5 90 150 % Ω 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 LTM4604E is guaranteed to meet performance specifications from 0°C to 85°C. Specifications over the – 40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. The LTM4604I is guaranteed over the full –40°C to 85°C temperature range. 4604f 3 LTM4604 TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs Output Current VIN = 2.5V 100 95 90 EFFICIENCY (%) 85 80 75 70 65 0 EFFICIENCY (%) 100 95 90 85 80 75 70 65 0 VOUT = 2.5V VOUT = 1.8V VOUT = 1.5V VOUT = 1.2V VOUT = 0.8V 1 3 OUTPUT CURRENT (A) "$" / Efficiency vs Output Current VIN = 3.3V 95 90 85 80 75 70 65 2 4 Efficiency vs Output Current VIN = 5V EFFICIENCY (%) VOUT = 1.8V VOUT = 1.5V VOUT = 1.2V VOUT = 0.8V 1 3 OUTPUT CURRENT (A) 2 4 "$" / VOUT = 3.3V VOUT = 2.5V VOUT = 1.8V VOUT = 1.5V VOUT = 1.2V VOUT = 0.8V 0 1 2 3 OUTPUT CURRENT (A) 4 "$" /! Minimum Input Voltage at 4A Load 3.5 3.0 2.5 VOUT (V) 2.0 1.5 1.0 0.5 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 VIN (V) 4604 G04 Load Transient Response Load Transient Response VOUT = 3.3V VOUT = 2.5V VOUT = 1.8V VOUT = 1.5V VOUT = 1.2V VOUT = 0.8V ILOAD 2A/DIV VOUT 20mV/DIV ILOAD 2A/DIV VOUT 20mV/DIV VIN = 5V 20μs/DIV VOUT = 1.2V COUT = 4 × 22μF, 6.3V CERAMICS 4604 G05 VIN = 5V 20μs/DIV VOUT = 1.5V COUT = 4 × 22μF, 6.3V CERAMICS 4604 G06 Load Transient Response Load Transient Response Load Transient Response ILOAD 2A/DIV VOUT 20mV/DIV ILOAD 2A/DIV ILOAD 2A/DIV VOUT 20mV/DIV VOUT 20mV/DIV 20μs/DIV VIN = 5V VOUT = 1.8V COUT = 3 × 22μF, 6.3V CERAMICS 4604 G07 VIN = 5V 20ms/DIV VOUT = 2.5V COUT = 3 ´ 22mF, 6.3V CERAMICS 4604 G08 VIN = 5V 20μs/DIV VOUT = 3.3V COUT = 2 × 22μF, 6.3V CERAMICS 4604 G09 4604f 4 LTM4604 TYPICAL PERFORMANCE CHARACTERISTICS Start-Up Start-Up VOUT 1V/DIV VOUT 1V/DIV IIN 1A/DIV IIN 1A/DIV VIN = 5V 200μs/DIV VOUT = 2.5V COUT = 4 × 22μF NO LOAD (0.01μF SOFT-START CAPACITOR) 4604 G10 VIN = 5V 200μs/DIV VOUT = 2.5V COUT = 4 × 22μF 4A LOAD (0.01μF SOFT-START CAPACITOR) 4604 G11 VFB vs Temperature 806 804 802 VFB (mV) 800 798 796 794 -50 -25 0 25 50 Temperature (C) 75 100 "$" /# Current Limit Foldback 1.6 1.4 1.2 1.0 VOUT (V) 0.8 0.6 0.4 VOUT = 1.5V VIN = 5V 0.2 VIN = 3.3V VIN = 2.5V 0 4 5 3 7 6 OUTPUT CURRENT (A) 8 4604 G12 Short-Circuit Protection 1.5V Short, No Load Short-Circuit Protection 1.5V Short, 4A Load VOUT 0.5V/DIV VOUT 0.5V/DIV IIN 4A/DIV IIN 1A/DIV 20μs/DIV 4604 G13 100μs/DIV 4604 G14 4604f 5 LTM4604 PIN FUNCTIONS VIN (B1, C1, C3-C7, D7, E6 and E7): Power Input Pins. Apply input voltage between these pins and GND pins. Recommend placing input decoupling capacitance directly between VIN pins and GND pins. VOUT (D8-D11, E8-E11, F6-F11, G6-G11): Power Output Pins. Apply output load between these pins and GND pins. Recommend placing output decoupling capacitance directly between these pins and GND pins. Review Table 4. GND (G3-G5, F3-F5, E4-E5, A1-A11, B6-B11, C8-C11): Power Ground Pins for Both Input and Output Returns. TRACK (E1): Output Voltage Tracking Pin. When the module is configured as a master output, then a soft-start capacitor is placed on the RUN/SS pin to ground to control the master ramp rate. Slave operation is performed by putting a resistor divider from the master output to ground, and connecting the center point of the divider to this pin on the slave regulator. If tracking is not desired, then connect the TRACK pin to VIN. Load current must be present for tracking. See Applications Information section. FB (G2): The Negative Input of the Error Amplifier. Internally, this pin is connected to VOUT with a 4.99k precision resistor. Different output voltages can be programmed with an additional resistor between FB and GND pins. Two power modules can current share when this pin is connected in parallel with the adjacent module’s FB pin. See Applications Information section. COMP (G1): Current Control Threshold and Error Amplifier Compensation Point. The current comparator threshold increases with this control voltage. Two power modules can current share when this pin is connected in parallel with the adjacent module’s COMP pin. PGOOD (F1): Output Voltage Power Good Indicator. Opendrain logic output that is pulled to ground when the output voltage is not within ±7.5% of the regulation point. RUN/SS (D1): Run Control and Soft-Start Pin. A voltage above 0.8V will turn on the module, and below 0.5V will turn off the module. This pin has a 1M resistor to VIN and a 1000pF capacitor to GND. See Application Infomation section for soft-start information. SW (B3 and B4): Switching Node of the circuit is used for testing purposes. This can be connected to copper on the board to improve thermal performance. Make sure not to connect it to other output pins. PGOOD F G COMP SW RUN/ SS GND FB TOP VIEW TRACK A 1 2 3 4 5 6 7 8 9 10 11 GND B VIN C D E VOUT 4604f 6 LTM4604 BLOCK DIAGRAM PGOOD RSS 1M CSS 1000pF M1 TRACK SUPPLY 4.99k 5.76k TRACK COMP INTERNAL COMP CONTROL, DRIVE M2 L C2 470pF R1 4.99k 0.5% 10μF 6.3V VOUT 22μF 6.3V ×3 GND VOUT 1.5V 4A 10μF 6.3V ×2 VIN 10μF 6.3V VIN 2.375V TO 5.5V RUN/SS CSSEXT 4604 BD FB RFB 5.76k SW Figure 1. Simplified LTM4604 Block Diagram DECOUPLING REQUIREMENTS TA = 25°C. Use Figure 1 Configuration. SYMBOL CIN COUT PARAMETER External Input Capacitor Requirement (VIN = 2.375V to 5.5V, VOUT = 1.5V) External Output Capacitor Requirement (VIN = 2.375V to 5.5V, VOUT = 1.5V) CONDITIONS IOUT = 4A IOUT = 4A MIN 10 22 100 TYP MAX UNITS μF μF 4604f 7 LTM4604 OPERATION Power Module Description The LTM4604 is a standalone non-isolated switch mode DC/DC power supply. It can deliver up to 4A of DC output current with few external input and output capacitors. This module provides a precise regulated output voltage programmable via one external resistor from 0.8V DC to 5.0V DC over a 2.375V to 5.5V input voltage. A typical application schematic is shown in Figure 15. The LTM4604 has an integrated constant frequency current mode regulator with built-in power MOSFETs with fast switching speed. The typical switching frequency is 1.25MHz. With current mode control and internal feedback loop compensation, the LTM4604 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. Current mode control provides cycle-by-cycle fast current limit. In addition, foldback current limiting is provided in an overcurrent condition while VOUT drops. Internal overvoltage and undervoltage comparators pull the opendrain PGOOD output low if the output feedback voltage exits a ±7.5% window around the regulation point. Furthermore, in an overvoltage condition, internal top FET M1 is turned off and bottom FET M2 is turned on and held on until the overvoltage condition clears. Pulling the RUN pin below 0.5V forces the controller into its shutdown state, turning off both M1 and M2. At low load current, the module works in continuous current mode by default to achieve minimum output voltage ripple. The TRACK pin is used for power supply tracking. See the Applications Information section. The LTM4604 is internally compensated to be stable over a wide operating range. Table 4 provides a guideline for input and output capacitance for several operating conditions. An excel loop analysis tool is provided for transient and stability analysis. The FB pin is used to program the output voltage with a single resistor connected to ground. 4604f 8 LTM4604 APPLICATIONS INFORMATION A typical LTM4604 application circuit is shown in Figure 15. External component selection is primarily determined by the maximum load current and output voltage. Refer to Table 4 for specific external capacitor requirements for a particular application. VIN to VOUT Step-Down Ratios There are restrictions in the maximum VIN and VOUT stepdown ratio that can be achieved for a given input voltage. The LTM4604 is 100% duty cycle, but the VIN to VOUT minimum dropout is a function of the load current. A typical 0.5V minimum is sufficient (see Typical Performance Characteristics). Output Voltage Programming The PWM controller has an internal 0.8V reference voltage. As shown in the Block Diagram, a 4.99k, 0.5% internal feedback resistor connects the VOUT and FB pins together. The output voltage will default to 0.8V with no feedback resistor. Adding a resistor RFB from the FB pin to GND programs the output voltage: VOUT = 0.8 V • 4.99k + RFB RFB Without considering the inductor current ripple, the RMS current of the input capacitor can be estimated as: ICIN(RMS) = IOUT(MAX ) η% • D • (1 – D) In the above equation, η% is the estimated efficiency of the power module. The bulk capacitor can be a switcherrated electrolytic aluminum capacitor, OS-CON capacitor for bulk input capacitance due to high inductance traces or leads. If a low inductance plane is used to power the device, then no input capacitance is required. The two internal 10μF ceramics are typically rated for 2A to 3A of RMS ripple current. The worst-case ripple current for the 4A maximum current is 2A or less. Output Capacitors The LTM4604 is designed for low output voltage ripple. The bulk output capacitors defined as COUT are chosen with low enough effective series resistance (ESR) to meet the output voltage ripple and transient requirements. COUT can be a low ESR tantalum capacitor, a low ESR polymer capacitor or an X5R/X7R ceramic capacitor. The typical output capacitance range is 22μF to 100μF. Additional output filtering may be required by the system designer if further reduction of output ripple or dynamic transient spike is required. Table 4 shows a matrix of different output voltages and output capacitors to minimize the voltage droop and overshoot during a 2A/μs transient. The table optimizes the total equivalent ESR and total bulk capacitance to maximize transient performance. The Linear Technology μModule Power Design Tool can be for further optimization. Fault Conditions: Current Limit and Overcurrent Foldback The LTM4604 has current mode control, 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 overload condition, the LTM4604 provides foldback current limiting as the output voltage falls. The LTM4604 device has overtemperature shutdown protection that inhibits switching operation around 150°C. 4604f Table 1. FB Resistor vs Output Voltage VOUT RFB 0.8V Open 1.2V 10k 1.5V 5.76k 1.8V 4.02k 2.5V 2.37k 3.3V 1.62k Input Capacitors The LTM4604 module should be connected to a low acimpedance DC source. Two 10μF ceramic capacitors are included inside the module. Additional input capacitors are only needed if a large load step is required up to a full 4A level. An input 47μF bulk capacitor is only needed if the input source impedance is compromised by long inductive leads or traces. For a buck converter, the switching duty cycle can be estimated as: D= VOUT VIN 9 LTM4604 APPLICATIONS INFORMATION Run Enable and Soft-Start The RUN/SS pin provides dual functions of enable and soft-start control. The RUN/SS pin is used to control turn on of the LTM4604. While this pin is below 0.5V, the LTM4604 will be in a 7μA low quiescent current state. A 0.8V threshold will enable the LTM4604. This pin can be used to sequence LTM4604 devices. The soft-start control is provided by a 1M pull-up resistor (RSS) and a 1000pF capacitor (CSS) as drawn in the Block Diagram. An external capacitor can be applied to the RUN/SS pin to increase the soft-start time. A typical value is 0.01μF. The approximate equation for soft-start is: ⎛ VIN ⎞ t SOFTSTART = ln ⎜ • RSS (CSS + CSSEXT ) ⎝ VIN – 1.8 V ⎟ ⎠ where RSS and CSS are shown in the Block Diagram of Figure 1, 1.8V is the soft-start upper range, and CSSEXT is the additional capacitance for further soft-start contol. The soft-start function can also be used to control the output ramp-up time, so that another regulator can be easily tracked. An independent ramp control signal can be applied to the master ramp, otherwise, connect the TRACK pin to VIN to disable tracking. Output Voltage Tracking Output voltage tracking can be programmed externally using the TRACK 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 to implement coincident tracking. The LTM4604 uses a very accurate 4.99k resistor for the top feedback resistor. Figure 2 shows an example of coincident tracking. VTRACK = RFB2 •V 4.99k + RFB2 MASTER CIN1 10μF 6.3V X5R OR X7R VIN PGOOD COMP GND VOUT FB RAMP CONTROL OR VIN RFB3 1.62k COUT1 22μF 6.3V ×3 X5R OR X7R LTM4604 RUN/SS TRACK CSSEXT VMASTER 3.3V 4A VIN 5V VIN 5V CIN2 10μF 6.3V X5R OR X7R VIN PGOOD COMP GND VOUT FB RFB2 5.76k RFB 5.76k COUT2 22μF 6.3V ×3 X5R OR X7R LTM4604 RUN/SS TRACK VSLAVE 1.5V 4A RFB1 4.99k 4604 F02 Figure 2 MASTER OUTPUT OUTPUT VOLTAGE (V) SLAVE OUTPUT TIME 4604 F03 VTRACK is the track ramp applied to the slave’s TRACK pin. VTRACK applies the track reference for the slave output up to the point of the programmed value at which VTRACK proceeds beyond the 0.8V reference value. The VTRACK pin must go beyond 0.8V to ensure the slave output has reached its final value. Load current must be present for proper tracking. Figure 3 4604f 10 LTM4604 APPLICATIONS INFORMATION Ratio metric 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. Linear Technology Tracker Cad26 can be used to implement different tracking scenarios. The Master and Slave data inputs can be used to implement the correct resistor values for coincident or ratio tracking. The master and slave regulators require load current for tracking down. Power Good The PGOOD pin is an open-drain pin that can be used to monitor valid output voltage regulation. This pin monitors a ±7.5% window around the regulation point. COMP Pin The pin is the external compensation pin. The module has already been internally compensated for all output voltages. Table 4 is provided for most application requirements. A spice model will be provided for other control loop optimizations. Parallel Operation The LTM4604 device is an inherently current mode controlled device. Parallel modules will have very good current sharing. This will balance the thermals on the design. Figure 16 shows a schematic of the parallel design. The voltage feedback changes with the variable N as more modules are paralleled. The equation: 4.99k + RFB = 0.8 V • N RFB VOUT N is the number of paralleled modules. Thermal Considerations and Output Current Derating The power loss curves in Figures 4 and 5 can be used in coordination with the load derating curves in Figures 6 through 13 for calculating an approximate θJA for the module with and without heat sinking methods with various airflow conditions. Thermal models are derived from several temperature measurements at the bench, and are correlated with thermal analysis software. Tables 2 and 3 provide a summary of the equivalent θJA for the noted conditions. These equivalent θJA parameters are correlated to the measured values and improve with air flow. The maximum junction temperature is monitored while the derating curves are derived. 2.0 1.8 1.6 1.4 WATTS 1.2 1.0 0.8 0.6 2.0 1.8 1.6 1.4 WATTS 1.2 1.0 0.8 0.6 0.4 0.2 0 0 1 5V TO 1.2V POWER LOSS 3.3V TO 1.2V POWER LOSS 3 2 LOAD CURRENT (A) 4 5 4604 F04 0.4 0.2 0 0 1 5V TO 2.5V POWER LOSS 3.3V TO 2.5V POWER LOSS 2 3 LOAD CURRENT (A) 4 4604 F05 5 Figure 4. 1.2V Power Loss Figure 5. 2.5V Power Loss 4604f 11 LTM4604 APPLICATIONS INFORMATION 4.0 3.5 LOAD CURRENT (A) LOAD CURRENT (A) 0LFM 200LFM 400LFM 70 75 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (°C) 4606 F06 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (°C) 4606 F07 3.0 2.5 2.0 1.5 1.0 0.5 0 Figure 6. 5VIN to 1.2VOUT No Heat Sink 4.0 3.5 LOAD CURRENT (A) LOAD CURRENT (A) 0LFM 200LFM 400LFM 70 75 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (°C) 4606 F08 Figure 7. 5VIN to 1.2VOUT with Heat Sink 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (°C) 4606 F09 3.0 2.5 2.0 1.5 1.0 0.5 0 Figure 8. 3.3VIN to 1.2VOUT No Heat Sink 4.0 3.5 LOAD CURRENT (A) 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 AMBIENT TEMPERATURE (°C) 4606 F10 Figure 9. 3.3VIN to 1.2VOUT with Heat Sink 4.0 3.5 LOAD CURRENT (A) 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (°C) 4606 F11 Figure 10. 5VIN to 2.5VOUT No Heat Sink Figure 11. 5VIN to 2.5VOUT with Heat Sink 4604f 12 LTM4604 APPLICATIONS INFORMATION 4.0 3.5 LOAD CURRENT (A) LOAD CURRENT (A) 0LFM 200LFM 400LFM 70 75 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (°C) 4606 F12 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (°C) 4606 F13 3.0 2.5 2.0 1.5 1.0 0.5 0 Figure 12. 3.3VIN to 2.5VOUT No Heat Sink Figure 13. 3.3VIN to 2.5VOUT with Heat Sink 4604f 13 LTM4604 APPLICATIONS INFORMATION Table 2. 1.2V Output DERATING CURVE Figures 6, 8 Figures 6, 8 Figures 6, 8 Figures 7, 9 Figures 7, 9 Figures 7, 9 VIN (V) 3.3, 5 3.3, 5 3.3, 5 3.3, 5 3.3, 5 3.3, 5 POWER LOSS CURVE Figure 4 Figure 4 Figure 4 Figure 4 Figure 4 Figure 4 AIR FLOW (LFM) 0 200 400 0 200 400 HEAT SINK None None None BGA Heat Sink BGA Heat Sink BGA Heat Sink θJA (°C/W) 25 22.5 21 21 20 18 Table 3. 2.5V Output DERATING CURVE Figures 10, 12 Figures 10, 12 Figures 10, 12 Figures 11, 13 Figures 11, 13 Figures 11, 13 VIN (V) 3.3, 5 3.3, 5 3.3, 5 3.3, 5 3.3, 5 3.3, 5 POWER LOSS CURVE Figure 5 Figure 5 Figure 5 Figure 5 Figure 5 Figure 5 AIR FLOW (LFM) 0 200 400 0 200 400 HEAT SINK None None None BGA Heat Sink BGA Heat Sink BGA Heat Sink θJA (°C/W) 25 21 21 21 18 16 Table 4. Output Voltage Response Versus Component Matrix (Refer to Figure 17), 0A to 2A Load Step Typical Measured Values CIN VOUT (V) (CERAMIC) 1.2 1.2 1.2 1.5 1.5 1.5 1.8 1.8 1.8 2.5 2.5 2.5 3.3 3.3 3.3 10μF 10μF 10μF 10μF 10μF 10μF 10μF 10μF 10μF 10μF 10μF 10μF 10μF 10μF 10μF CIN (Bulk) 56μF Aluminum 56μF Aluminum 56μF Aluminum 56μF Aluminum 56μF Aluminum 56μF Aluminum 56μF Aluminum 56μF Aluminum 56μF Aluminum 56μF Aluminum 56μF Aluminum 56μF Aluminum 56μF Aluminum 56μF Aluminum 56μF Aluminum COUT (CERAMIC) 100μF 6.3V 22μF ×4 22μF ×4 100μF 6.3V 22μF ×4 22μF ×4 100μF 6.3V 22μF ×3 22μF ×3 100μF 6.3V 22μF ×3 22μF ×3 100μF 6.3V 22μF ×3 22μF ×3 CCOMP None None None None None None None None None None None None None None None VIN (V) 2.5 3.3 5 2.5 3.3 5 2.5 3.3 5 2.5 3.3 5 2.5 3.3 5 DROOP (mV) 21 23 24 19 21 21 25 30 30 22 25 25 22 25 25 PEAK-TOPEAK(mV) 43 45 46 41 43 43 50 60 60 45 55 55 50 56 56 RECOVERY LOAD STEP (μs) (A/μs) 10 10 10 10 10 10 10 10 10 12 12 12 15 15 15 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 RFB (kΩ) 10 10 10 5.76 5.76 5.76 4.02 4.02 4.02 2.37 2.37 2.37 1.62 1.62 1.62 4604f 14 LTM4604 APPLICATIONS INFORMATION Safety Considerations The LTM4604 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 needs to be provided to protect each unit from catastrophic failure. Layout Checklist/Example The high integration of LTM4604 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, GND 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, GND 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. VIN • Do not put vias directly on the pads unless they are capped. • SW pads can be soldered to board to improve thermal performance. Figure14 gives a good example of the recommended layout. GND VOUT COUT COUT COUT • • • •• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •• • • CIN • • SW • • • • • • • • • • •• GND •• 4604 F14 Figure 14. Recommended PCB Layout VIN 2.375V TO 5.5V CIN 10μF 6.3V X5R OR X7R OPEN-DRAIN PULL UP VIN PGOOD COMP CSSEXT 0.01μF GND VOUT FB RFB 5.69k 0.5% LTM4604 RUN/SS TRACK VOUT 1.5V 4A COUT 22μF ×3 6.3V X5R OR X7R REFER TO TABLE 4 4604 F15 Figure 15. Typical 2.375V to 5.5V Input, 1.5V at 4A Design 4604f 15 LTM4604 TYPICAL APPLICATIONS VIN 2.375V TO 5V CIN1 10μF 6.3V X5R OR X7R OPEN-DRAIN PULL UP VIN PGOOD COMP CSSEXT 0.01μF GND VOUT FB RFB 2.87k COUT1 22μF ×3 6.3V X5R OR X7R REFER TO TABLE 4 VOUT 1.5V 8A CIN2 10μF 6.3V X5R OR X7R VIN PGOOD COMP GND 4604 F16 VOUT = 0.8V × ((4.99k/N) + RFB)/RFB WHERE N IS THE NUMBER OF PARALLEL DEVICES LTM4604 RUN/SS TRACK VOUT FB COUT2 22μF ×3 6.3V X5R OR X7R REFER TO TABLE 4 LTM4604 RUN/SS TRACK Figure 16. Two LTM4604s in Parallel, 1.5V at 8A Design 4604f 16 LTM4604 TYPICAL APPLICATIONS VIN 3.3V TO 5V CIN 10μF 6.3V X5R OR X7R 50k OPEN-DRAIN PULL UP VIN PGOOD COMP CSSEXT 0.01μF GND VOUT FB RFB 2.37k LTM4604 RUN/SS TRACK VOUT 2.5V 4A COUT 22μF ×3 6.3V X5R OR X7R REFER TO TABLE 4 4604 F17 Figure 17. 3.3V to 5V Input, 2.5V at 4A Design 4604f 17 LTM4604 aaa Z 4 aaa Z bbb Z PAD “A1” CORNER Z 6.350 5.080 3.810 2.540 1.270 0.4445 0.000 0.4445 1.270 2.540 3.810 5.080 6.350 18 LGA Package 66-Lead (15mm × 9mm × 2.32mm) (Reference LTC DWG # 05-08-1807 Rev A) 12.70 BSC X Y 15.00 BSC 2.19 – 2.45 0.864 – 0.914 PACKAGE DESCRIPTION G F 0.864 – 0.914 9.00 BSC 0.29 – 0.35 1.90 – 2.10 MOLD CAP SUBSTRATE 7.620 BSC E D C B DETAIL A 1.27 BSC A PADS SEE NOTES DETAIL A PACKAGE SIDE VIEW 3 PACKAGE TOP VIEW 11 10 9 8 7 6 5 PACKAGE BOTTOM VIEW 4 3 2 1 PAD 1 NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994 2. ALL DIMENSIONS ARE IN MILLIMETERS 3 LAND DESIGNATION PER JESD MO-222 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 A MARKED FEATURE 4 3.810 2.540 1.270 5. PRIMARY DATUM -Z- IS SEATING PLANE 6. THE TOTAL NUMBER OF PADS: 66 SYMBOL TOLERANCE 0.15 aaa 0.10 bbb COMPONENT PIN “A1” TRAY PIN 1 BEVEL LTMXXXXXX mModule 0.4445 0.000 0.4445 1.270 2.540 3.810 PACKAGE IN TRAY LOADING ORIENTATION LGA 66 0607 REV A SUGGESTED PCB LAYOUT TOP VIEW 4604f LTM4604 PACKAGE DESCRIPTION Pin Assignment Table (Arranged by Pin Number) PIN NAME A1 A2 A3 A4 A5 A6 A7 A8 A9 GND GND GND GND GND GND GND GND GND PIN NAME B1 B2 B3 B4 B5 B6 B7 B8 B9 VIN – SW SW – GND GND GND GND PIN NAME C1 C2 C3 C4 C5 C6 C7 C8 C9 VIN – VIN VIN VIN VIN VIN GND GND PIN NAME D1 D2 D3 D4 D5 D6 D7 D8 D9 RUN/SS – – – – – VIN VOUT VOUT PIN NAME E1 E2 E3 E4 E5 E6 E7 E8 E9 TRACK – – GND GND VIN VIN VOUT VOUT PIN NAME F1 F2 F3 F4 F5 F6 F7 F8 F9 PGOOD – GND GND GND VOUT VOUT VOUT VOUT PIN NAME G1 G2 G3 G4 G5 G6 G7 G8 G9 COMP FB GND GND GND VOUT VOUT VOUT VOUT A10 GND A11 GND B10 GND B11 GND C10 GND C11 GND D10 VOUT D11 VOUT E10 VOUT E11 VOUT F10 VOUT F11 VOUT G10 VOUT G11 VOUT 4604f 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. 19 LTM4604 RELATED PARTS PART NUMBER LTC2900 LTC2923 LTM4600 LTM4601 LTM4602 LTM4603 LTM4608 DESCRIPTION Quad Supply Monitor with Adjustable Reset Timer Power Supply Tracking Controller 10A DC/DC μModule 12A DC/DC μModule with PLL, Output Tracking/ Margining and Remote Sensing 6A DC/DC μModule 6A DC/DC μModule with PLL and Output Tracking/ Margining and Remote Sensing 8A Low Voltage μModule COMMENTS Monitors Four Supplies; Adjustable Reset Timer Tracks Both Up and Down; Power Supply Sequencing Basic 10A DC/DC μModule Synchronizable, PolyPhase Operation, LTM4601-1 Version has no Remote Sensing Pin Compatible with the LTM4600 Synchronizable, PolyPhase Operation, LTM4603-1 Version has no Remote Sensing, Pin Compatible with the LTM4601 2.375V ≤ VIN ≤ 5V, Parallel for Higher Output Current, 9mm × 15mm × 2.8mm 4604f 20 Linear Technology Corporation (408) 432-1900 ● FAX: (408) 434-0507 ● LT 0807 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 www.linear.com © LINEAR TECHNOLOGY CORPORATION 2007