LTM8050 58V, 2A Step-Down Module Regulator FEATURES n n n n n n n n n DESCRIPTION Wide Input Voltage Range: 3.6V to 58V (60V Absolute Maximum) Up to 2A Output Current Parallelable for Increased Output Current 0.8V to 24V Output Voltage Adjustable Switching Frequency: 100kHz to 2.4MHz Configurable as an Inverter Current Mode Control Programmable Soft-Start 9mm x 15mm x 4.92mm BGA Package APPLICATIONS n n n n n Automotive Battery Regulation Power for Portable Products Distributed Supply Regulation Industrial Supplies Wall Transformer Regulation The LTM(R)8050 is a 58VIN, 2A step down Module(R) (micromodule) converter. Included in the package are the switching controller, power switches, inductor and all support components. Operating over an input voltage range of 3.6V to 58V, the LTM8050 supports an output voltage range of 0.8V to 24V and a switching frequency range of 100kHz to 2.4MHz, each set by a single resistor. Only the bulk input and output filter capacitors are needed to finish the design. The LTM8050 is packaged in a 9mm x 15mm x 4.92mm ball grid array (BGA) package suitable for automated assembly by standard surface mount equipment. The LTM8050 is available with SnPb (BGA) or RoHS compliant terminal finish. L, LT, LTC, LTM, Linear Technology, the Linear logo, Module and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Click to view associated TechClip Videos. TYPICAL APPLICATION Efficiency vs Output Current, 12VOUT 92 12VOUT, 2A Module Regulator VIN 4.7F RUN/SS BIAS PGOOD RT 57.6k f = 600kHz 22F FB SYNC VIN = 36V AUX LTM8050 SHARE 90 VOUT 12V AT 2A VOUT GND EFFICIENCY (%) VIN* 17V TO 58V VIN = 24V 88 VIN = 48V 86 84 34.8k 82 *RUNNING VOLTAGE RANGE. PLEASE REFER TO APPLICATIONS INFORMATION SECTION FOR START-UP DETAILS 80 8050 TA01a 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 8050 TA01b 8050fc For more information www.linear.com/LTM8050 1 LTM8050 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Notes 1, 3) VIN, RUN/SS Voltage..................................................60V FB, RT, SHARE Voltage................................................5V VOUT, AUX..................................................................25V PGOOD, SYNC, BIAS..................................................25V VIN + BIAS..................................................................72V Maximum Junction Temperature (Note 2)............. 125C Solder Temperature................................................ 245C Storage Temperature............................................. 125C 1 2 TOP VIEW 3 4 5 VOUT 6 7 GND A BANK 1 B C D E BANK 2 BANK 3 F RT G H AUX SHARE J BIAS PGOOD K FB L VIN RUN/SS SYNC BGA PACKAGE 70-PIN (15mm x 9mm x 4.92mm) TJMAX = 125C, JA = 24.4C/W, JC(BOTTOM) = 11.5C/W, JC(TOP) = 42.7C/W, JB = 18.7C/W VALUES DETERMINED PER JESD51-9, MAX OUTPUT POWER WEIGHT = 1.8 GRAMS ORDER INFORMATION http://www.linear.com/product/LTM8050#orderinfo PART MARKING* PART NUMBER PAD OR BALL FINISH LTM8050EY#PBF SAC305 (RoHS) DEVICE FINISH CODE PACKAGE TYPE MSL RATING LTM8050Y e1 BGA 3 TEMPERATURE RANGE (SEE NOTE 2) -40C to 125C LTM8050IY#PBF SAC305 (RoHS) LTM8050Y e1 BGA 3 -40C to 125C LTM8050IY SnPb (63/37) LTM8050Y e0 BGA 3 -40C to 125C LTM8050MPY#PBF SAC305 (RoHS) LTM8050Y e1 BGA 3 -55C to 125C LTM8050MPY SnPb (63/37) LTM8050Y e0 BGA 3 -55C to 125C Consult Marketing for parts specified with wider operating temperature ranges. *Device temperature grade is indicated by a label on the shipping container. Pad or ball finish code is per IPC/JEDEC J-STD-609. * Recommended LGA and BGA PCB Assembly and Manufacturing Procedures: www.linear.com/umodule/pcbassembly * Terminal Finish Part Marking: www.linear.com/leadfree * LGA and BGA Package and Tray Drawings: www.linear.com/packaging 2 8050fc For more information www.linear.com/LTM8050 LTM8050 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = 12V, RUN/SS = 12V, BIAS = 3V unless otherwise noted. (Note 2) PARAMETER CONDITIONS MIN Minimum Input Voltage Output DC Voltage TYP MAX 3.6 l 0 < IOUT 2A; RFB Open 0 < IOUT 2A; RFB = 16.9k; VIN = 32V 0.8 24 Output DC Current 0 UNITS V V V 2 A Quiescent Current into VIN RUN/SS = 0V Not Switching BIAS = 0V, Not Switching 0.01 35 120 1 60 160 A A A Quiescent Current into BIAS RUN/SS = 0V Not Switching BIAS = 0V, Not Switching 0.01 82 1 0.5 120 5 A A A Line Regulation 5.5V < VIN < 58V, IOUT = 1A 0.3 % Load Regulation 0A < IOUT < 2A 0.3 % Output Voltage Ripple (RMS) 0A < IOUT < 2A 10 mV Switching Frequency RT = 45.3k 750 kHz Voltage (at FB Pin) l 775 770 Internal Feedback Resistor 790 499 Minimum BIAS Voltage for Proper Operation RUN/SS Pin Current 805 810 RUN/SS = 2.5V 6 RUN Input High Voltage k 2.8 V 10 A 2.5 V RUN Input Low Voltage 0.2 PGOOD Threshold (at FB Pin) VOUT Rising PGOOD Leakage Current PGOOD = 30V PGOOD Sink Current PGOOD = 0.4V SYNC Input Low Threshold fSYNC = 550kHz SYNC Input High Threshold fSYNC = 550kHz SYNC Bias Current SYNC = 0V 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 LTM8050E is guaranteed to meet performance specifications from 0C to 125C internal. Specifications over the full -40C to 125C internal operating temperature range are assured by design, characterization and correlation with statistical process controls. The 730 0.1 200 mV mV mV 1 600 A A 0.5 0.7 V V V 0.1 A LTM8050I is guaranteed to meet specifications over the full -40C to 125C internal operating temperature range. The LTM8050MP is guaranteed to meet specifications over the full -55C to 125C internal operating temperature range. Note that the maximum internal temperature is determined by specific operating conditions in conjunction with board layout, the rated package thermal resistance and other environmental factors. Note 3: Unless otherwise noted, the absolute minimum voltage is zero. 8050fc For more information www.linear.com/LTM8050 3 LTM8050 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25C, unless otherwise noted. 85 75 5VIN 12VIN 24VIN 36VIN 48VIN 65 94 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 60 2.0 92 88 EFFICIENCY (%) EFFICIENCY (%) 90 86 84 82 76 12VIN 24VIN 36VIN 48VIN 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 91 36VIN 48VIN 0.5 1.0 OUTPUT CURRENT (A) 94 88 90 86 84 24VIN 36VIN 48VIN 0.5 1.0 1.5 OUTPUT CURRENT (A) 1.5 8050 G07 0.5 1.0 1.5 OUTPUT CURRENT (A) 86 82 36VIN 48VIN 0 0.5 1.0 OUTPUT CURRENT (A) Input Current vs Output Current 2.5VOUT 75 1.2 70 1.0 65 60 45 1.00 5VIN 12VIN 24VIN 36VIN 48VIN 1.25 1.50 VOUT (V) 1.75 1.5 8050 G06 1.4 50 8050 G03 Efficiency vs Output Current, 18VOUT 84 2.0 2.0 88 80 55 89 0 8050 G02 92 0 12VIN 24VIN 36VIN 48VIN 8050 G05 EFFICIENCY (%) 93 0 65 2.0 Efficiency, VOUT 2V, 2A Load, BIAS = 5V 95 87 75 70 Efficiency vs Output Current, 12VOUT 8050 G04 97 EFFICIENCY (%) 0.5 1.0 1.5 OUTPUT CURRENT (A) 80 90 80 2.0 99 4 0 82 Efficiency vs Output Current, 24VOUT 85 12VIN 24VIN 36VIN 48VIN 8050 G01 92 78 70 65 Efficiency vs Output Current, 8VOUT 80 75 EFFICIENCY (%) 70 Efficiency vs Output Current, 5VOUT 85 EFFICIENCY (%) 80 60 90 80 EFFICIENCY (%) EFFICIENCY (%) 85 Efficiency vs Output Current, 3.3VOUT 2.00 8050 G08 INPUT CURRENT (A) 90 Efficiency vs Output Current, 2.5VOUT Operating conditions are per Table 1 and 5VIN 12VIN 24VIN 36VIN 48VIN 0.8 0.6 0.4 0.2 0 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 8050 G09 8050fc For more information www.linear.com/LTM8050 LTM8050 TYPICAL PERFORMANCE CHARACTERISTICS Operating conditions are per Table 1 and TA = 25C, unless otherwise noted. 1.0 INPUT CURRENT (A) 0.6 0.5 0.4 0.3 0.2 0.6 0.4 0 2.0 1.2 24VIN 36VIN 48VIN 0.6 0.4 0.2 0 0.5 1.0 1.5 OUTPUT CURRENT (A) Input Current vs Output Current 18VOUT 0 0.5 1.0 OUTPUT CURRENT (A) 80 8050 G16 2.0 8050 G12 Input Current vs Output Current 24VOUT 36VIN 48VIN 0.8 0.6 0.4 0 1.5 3 2 RT = 215k (200kHz) RT = 93.1k (400kHz) RT = 57.6k (600kHz) RT = 33.2k (900kHz) 0 20 40 60 INPUT VOLTAGE (V) 0 8050 G14 4 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 1.0 16 1 40 60 INPUT VOLTAGE (V) 0 1.2 5 OUTPUT CURRENT (A) 100 20 0.4 Output Current vs VIN Output Shorted 200 0 0.6 0.2 8050 G13 RT = 215k (200kHz) RT = 93.1k (400kHz) RT = 57.6k (600kHz) RT = 33.2k (900kHz) 300 0.8 1.4 36VIN 48VIN 0.4 0 1.0 8050 G11 0.6 2.0 1.2 0 2.0 0.2 400 INPUT CURRENT (mA) 0.5 1.0 1.5 OUTPUT CURRENT (A) 0.8 Input Current vs VIN Output Shorted 0 0 1.0 0.8 12VIN 24VIN 36VIN 48VIN 0.2 8050 G10 INPUT CURRENT (A) INPUT CURRENT (A) 0.5 1.0 1.5 OUTPUT CURRENT (A) Input Current vs Output Current 12VOUT 1.0 0 0.8 INPUT CURRENT (A) 1.2 0 Input Current vs Output Current 8VOUT 1.4 0.2 0.1 0 1.6 12VIN 24VIN 36VIN 48VIN INPUT CURRENT (A) 0.7 INPUT CURRENT (A) 1.2 12VIN 24VIN 36VIN 48VIN Input Current vs Output Current 5VOUT BIAS CURRENT (mA) 0.8 Input Current vs Output Current 3.3VOUT 80 8050 G16 0.5 1.0 OUTPUT CURRENT (A) 1.5 8050 G15 BIAS Current vs Output Current 2.5VOUT BIAS = 5V 12VIN 24VIN 36VIN 48VIN 12 8 4 0 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 8050 G18 8050fc For more information www.linear.com/LTM8050 5 LTM8050 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25C, unless otherwise noted. 10 5 50 12VIN 24VIN 36VIN 48VIN BIAS Current vs Output Current 8VOUT BIAS = 5V 12VIN 24VIN 36VIN 48VIN 40 20 10 30 20 10 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 0 2.0 0 8050 G19 BIAS Current vs Output Current 12VOUT BIAS = 5V 50 24VIN 36VIN 48VIN 0.5 1.0 1.5 OUTPUT CURRENT (A) 0 2.0 BIAS Current vs Output Current 18VOUT BIAS = 5V 80 36VIN 48VIN 20 10 30 20 10 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 8050 G21 BIAS Current vs Output Current 24VOUT BIAS = 5V 36VIN 48VIN 70 40 30 0 8050 G20 BIAS CURRENT (mA) 40 BIAS Current vs Output Current 5VOUT BIAS = 5V BIAS CURRENT (mA) BIAS CURRENT (mA) 15 0 BIAS CURRENT (mA) 30 12VIN 24VIN 36VIN 48VIN BIAS CURRENT (mA) BIAS CURRENT (mA) 20 BIAS Current vs Output Current 3.3VOUT BIAS = 5V Operating conditions are per Table 1 and 60 50 40 30 20 10 0 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 0 2.0 0 8050 G22 Minimum VIN vs VOUT Maximum Load, BIAS = 5V 40 4.00 0.5 1.0 OUTPUT CURRENT (A) 0 1.5 8050 G23 Minimum VIN vs Output Current 1.8VOUT and Below, BIAS = 5V 4.2 35 25 20 15 MINIMUM VIN (V) MINIMUM VIN (V) MINIMUM VIN (V) 3.75 10 3.50 3.25 1.5 8050 G24 Minimum VIN vs Output Current 2.5VOUT, BIAS = 5V 4.0 3.9 3.8 3.7 3.6 5 6 0.5 1.0 OUTPUT CURRENT (A) 4.1 30 0 0 0 5 10 15 VOUT (V) 20 25 8050 G25 3.00 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 8050 G26 3.5 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 8050 G27 8050fc For more information www.linear.com/LTM8050 LTM8050 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25C, unless otherwise noted. 6.0 Minimum VIN vs Output Current 3.3VOUT, BIAS = VOUT 7.55 Minimum VIN vs Output Current 5VOUT, BIAS = VOUT 4.5 4.0 RUNNING TO START, RUN CONTROL TO START, RUN = VIN 3.5 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 7.35 7.30 7.25 7.20 7.05 MINIMUM VIN (V) MINIMUM VIN (V) 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 7.5 2.0 RUNNING TO START, RUN CONTROL TO START, RUN = VIN Minimum VIN vs Output Current 18VOUT, BIAS = VOUT 35 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 23 22 21 30 25 0 0.5 1.0 OUTPUT CURRENT (A) MINIMUM VIN (V) 10 0.5 1.0 1.5 OUTPUT CURRENT (A) 30 29 28 2.0 8050 G34 0.5 1.0 OUTPUT CURRENT (A) 1.5 8050 G33 Minimum VIN vs Output Current -8VOUT, BIAS = GND 25 RUNNING TO START, RUN CONTROL TO START, RUN = VIN 20 15 10 0 0 8050 G32 5 5 0 31 25 1.5 RUNNING TO START, RUN CONTROL TO START, RUN = VIN 20 15 Minimum VIN vs Output Current 24VOUT, BIAS = 5V 26 25 20 8050 G30 32 Minimum VIN vs Output Current -5VOUT, BIAS = GND RUNNING TO START, RUN CONTROL TO START, RUN = VIN 2.0 27 8050 G31 Minimum VIN vs Output Current -3.3VOUT, BIAS = GND 0.5 1.0 1.5 OUTPUT CURRENT (A) 33 20 2.0 0 34 24 19 RUNNING TO START, RUN CONTROL TO START, RUN = VIN 8050 G29 25 13 9.0 8.0 26 14 9.5 7.10 Minimum VIN vs Output Current 12VOUT, BIAS = VOUT 12 MINIMUM VIN (V) 10.0 8.5 8050 G28 15 0 10.5 7.15 16 11 11.0 MINIMUM VIN (V) 17 0 11.5 7.40 MINIMUM VIN (V) 3.0 Minimum VIN vs Output Current 8VOUT, BIAS = VOUT 12.0 MINIMUM VIN (V) MINIMUM VIN (V) MINIMUM VIN (V) 7.45 5.0 12.5 RUNNING TO START, RUN CONTROL TO START, RUN = VIN 7.50 5.5 Operating conditions are per Table 1 and 15 10 5 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 8050 G35 0 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 8050 G36 8050fc For more information www.linear.com/LTM8050 7 LTM8050 TYPICAL PERFORMANCE CHARACTERISTICS Operating conditions are per Table 1 and TA = 25C, unless otherwise noted. 25 Minimum VIN vs Output Current -12VOUT, BIAS = GND 15 10 5 0 25 0 0.5 1.0 OUTPUT CURRENT (A) 10 0 1.5 Minimum VIN vs Output Current -24VOUT, BIAS = GND 10 5 0.2 0.3 0.4 OUTPUT CURRENT (A) 10 0 0.5 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 8050 G40 Internal Temperature Rise vs Output Current, 5VOUT 30 20 10 12VIN 24VIN 36VIN 48VIN 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 TEMPERATURE RISE (C) TEMPERATURE RISE (C) 5VIN 12VIN 24VIN 36VIN 48VIN 8050 G39 30 8 8050 G38 20 Internal Temperature Rise vs Output Current, 3.3VOUT 0 0.75 30 15 0.1 0.25 0.50 OUTPUT CURRENT (A) Internal Temperature Rise vs Output Current, 2.5VOUT RUNNING TO START, RUN CONTROL TO START, RUN = VIN 0 0 8050 G37 TEMPERATURE RISE (C) MINIMUM VIN (V) 15 5 20 0 RUNNING TO START, RUN CONTROL TO START, RUN = VIN 20 MINIMUM VIN (V) 20 MINIMUM VIN (V) 25 RUNNING TO START, RUN CONTROL TO START, RUN = VIN Minimum VIN vs Output Current -18VOUT, BIAS = GND 20 10 0 12VIN 24VIN 36VIN 48VIN 0 8050 G41 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 8050 G42 8050fc For more information www.linear.com/LTM8050 LTM8050 TYPICAL PERFORMANCE CHARACTERISTICS Operating conditions are per Table 1 and TA = 25C, unless otherwise noted. 40 30 20 10 0 12VIN 24VIN 36VIN 48VIN 0 0.5 1.0 1.5 OUTPUT CURRENT (A) TEMPERATURE RISE (C) TEMPERATURE RISE (C) 40 Internal Temperature Rise vs Output Current, 8VOUT TEMPERATURE RISE (C) TEMPERATURE RISE (C) 30 20 10 24VIN 36VIN 48VIN 0.5 1.0 OUTPUT CURRENT (A) 10 50 40 0 20 24VIN 36VIN 48VIN 0 8050 G43 Internal Temperature Rise vs Output Current, 18VOUT 0 30 0 2.0 Internal Temperature Rise vs Output Current, 12VOUT 1.5 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 8050 G44 Internal Temperature Rise vs Output Current, 24VOUT 40 30 20 10 0 36VIN 48VIN 58VIN 0 0.5 1.0 OUTPUT CURRENT (A) 8050 G45 Soft-Start Waveform for Various CSS Values 1A Resistive Load, DC1723A Demo Board 1.5 8050 G46 Output Ripple at 2A Load, Standard DC1723A Demo Board CSS = 0F FREE RUNNING (400kHz) CSS = 0.1F 1V/DIV 600kHz SYNC 10mV/DIV CSS = 0.47F 800kHz SYNC 200s/DIV RSS = 100k 8050 G47 1s/DIV 8050 G48 REFER TO DC1723A DEMO MANUAL FOR PROPER RIPPLE MEASUREMENT TECHNIQUE 8050fc For more information www.linear.com/LTM8050 9 LTM8050 PIN FUNCTIONS PACKAGE ROW AND COLUMN LABELING MAY VARY AMONG Module PRODUCTS. REVIEW EACH PACKAGE LAYOUT CAREFULLY. VOUT (Bank 1): Power Output Pins. Apply the output filter capacitor and the output load between these pins and GND pins. GND (Bank 2): Tie these GND pins to a local ground plane below the LTM8050 and the circuit components. In most applications, the bulk of the heat flow out of the LTM8050 is through these pads, so the printed circuit design has a large impact on the thermal performance of the part. See the PCB Layout and Thermal Considerations sections for more details. Return the feedback divider (RFB) to this net. VIN (Bank 3): The VIN pin supplies current to the LTM8050's internal regulator and to the internal power switch. This pin must be locally bypassed with an external, low ESR capacitor; see Table 1 for recommended values. AUX (Pin G5): Low Current Voltage Source for BIAS. In many designs, the BIAS pin is simply connected to VOUT. The AUX pin is internally connected to VOUT and is placed adjacent to the BIAS pin to ease printed circuit board routing. Although this pin is internally connected to VOUT, it is not intended to deliver a high current, so do not draw current from this pin to the load. If this pin is not tied to BIAS, leave it floating. BIAS (Pin H5): The BIAS pin connects to the internal power bus. Connect to a power source greater than 2.8V and less than 25V. If the output is greater than 2.8V, connect this pin there. If the output voltage is less, connect this to a voltage source between 2.8V and 25V. Also, make sure that BIAS + VIN is less than 72V. 10 RUN/SS (Pin L5): Pull the RUN/SS pin below 0.2V to shut down the LTM8050. Tie to 2.5V or more for normal operation. If the shutdown feature is not used, tie this pin to the VIN pin. RUN/SS also provides a soft-start function; see the Applications Information section. SYNC (Pin L6): This is the external clock synchronization input. Ground this pin for low ripple Burst Mode operation at low output loads. Tie to a stable voltage source greater than 0.7V to disable Burst Mode operation. Do not leave this pin floating. Tie to a clock source for synchronization. Clock edges should have rise and fall times faster than 1s. See the Synchronization section in Applications Information. RT (Pin G7): The RT pin is used to program the switching frequency of the LTM8050 by connecting a resistor from this pin to ground. Table 2 gives the resistor values that correspond to the resultant switching frequency. Minimize the capacitance at this pin. SHARE (Pin H7): Tie this to the SHARE pin of another LTM8050 when paralleling the outputs. Otherwise, do not connect. PGOOD (Pin J7): The PGOOD pin is the open-collector output of an internal comparator. PGOOD remains low until the FB pin is within 10% of the final regulation voltage. PGOOD output is valid when VIN is above 3.6V and RUN/SS is high. If this function is not used, leave this pin floating. FB (Pin K7): The LTM8050 regulates its FB pin to 0.79V. Connect the adjust resistor from this pin to ground. The value of RFB is given by the equation RFB = 394.21/(VOUT - 0.79), where RFB is in k. 8050fc For more information www.linear.com/LTM8050 LTM8050 BLOCK DIAGRAM VIN VOUT 8.2H 0.2F 499k 1% 15pF 4.4F AUX BIAS RUN/SS SHARE CURRENT MODE CONTROLLER SYNC GND RT PGOOD FB 8050 BD OPERATION The LTM8050 is a standalone nonisolated step-down switching DC/DC power supply that can deliver up to 2A of output current. This module provides a precisely regulated output voltage programmable via one external resistor from 0.8V to 24V. The input voltage range is 3.6V to 58V. Given that the LTM8050 is a step-down converter, make sure that the input voltage is high enough to support the desired output voltage and load current. As shown in the Block Diagram, the LTM8050 contains a current mode controller, power switching element, power inductor, power Schottky diode and a modest amount of input and output capacitance. The LTM8050 is a fixed frequency PWM regulator. The switching frequency is set by simply connecting the appropriate resistor value from the RT pin to GND. An internal regulator provides power to the control circuitry. The bias regulator normally draws power from the VIN pin, but if the BIAS pin is connected to an external voltage higher than 2.8V, bias power will be drawn from the external source (typically the regulated output voltage). This improves efficiency. The RUN/SS pin is used to place the LTM8050 in shutdown, disconnecting the output and reducing the input current to less than 1A. To further optimize efficiency, the LTM8050 automatically switches to Burst Mode(R) operation in light load situations. Between bursts, all circuitry associated with controlling the output switch is shut down reducing the input supply current to 50A in a typical application. The oscillator reduces the LTM8050's operating frequency when the voltage at the FB pin is low. This frequency foldback helps to control the output current during start-up and overload. The LTM8050 contains a power good comparator which trips when the FB pin is at roughly 90% of its regulated value. The PGOOD output is an open-collector transistor that is off when the output is in regulation, allowing an external resistor to pull the PGOOD pin high. Power good is valid when the LTM8050 is enabled and VIN is above 3.6V. The LTM8050 is equipped with a thermal shutdown that will inhibit power switching at high junction temperatures. The activation threshold of this function, however, is above 125C to avoid interfering with normal operation. Thus, prolonged or repetitive operation under a condition in which the thermal shutdown activates may damage or impair the reliability of the device. 8050fc For more information www.linear.com/LTM8050 11 LTM8050 APPLICATIONS INFORMATION For most applications, the design process is straight forward, summarized as follows: 1. Look at Table 1 and find the row that has the desired input range and output voltage. 2. Apply the recommended CIN, COUT, RFB and RT values. 3. Connect BIAS as indicated. While these component combinations have been tested for proper operation, it is incumbent upon the user to verify proper operation over the intended system's line, load and environmental conditions. Bear in mind that the maximum output current is limited by junction temperature, the relationship between the input and output voltage magnitude and polarity and other factors. Please refer to the graphs in the Typical Performance Characteristics section for guidance. The maximum frequency (and attendant RT value) at which the LTM8050 should be allowed to switch is given in Table 1 in the fMAX column, while the recommended frequency (and RT value) for optimal efficiency over the given input condition is given in the fOPTIMAL column. There are additional conditions that must be satisfied if the synchronization function is used. Please refer to the Synchronization section for details. Capacitor Selection Considerations The CIN and COUT capacitor values in Table 1 are the minimum recommended values for the associated operating conditions. Applying capacitor values below those indicated in Table 1 is not recommended, and may result in undesirable operation. Using larger values is generally acceptable, and can yield improved dynamic response, if it is necessary. Again, it is incumbent upon the user to verify proper operation over the intended system's line, load and environmental conditions. 12 Ceramic capacitors are small, robust and have very low ESR. However, not all ceramic capacitors are suitable. X5R and X7R types are stable over temperature and applied voltage and give dependable service. Other types, including Y5V and Z5U have very large temperature and voltage coefficients of capacitance. In an application circuit they may have only a small fraction of their nominal capacitance resulting in much higher output voltage ripple than expected. Ceramic capacitors are also piezoelectric. In Burst Mode operation, the LTM8050's switching frequency depends on the load current, and can excite a ceramic capacitor at audio frequencies, generating audible noise. Since the LTM8050 operates at a lower current limit during Burst Mode operation, the noise is typically very quiet to a casual ear. If this audible noise is unacceptable, use a high performance electrolytic capacitor at the output. It may also be a parallel combination of a ceramic capacitor and a low cost electrolytic capacitor. A final precaution regarding ceramic capacitors concerns the maximum input voltage rating of the LTM8050. A ceramic input capacitor combined with trace or cable inductance forms a high Q (under damped) tank circuit. If the LTM8050 circuit is plugged into a live supply, the input voltage can ring to twice its nominal value, possibly exceeding the device's rating. This situation is easily avoided; see the Hot-Plugging Safely section. Frequency Selection The LTM8050 uses a constant frequency PWM architecture that can be programmed to switch from 100kHz to 2.4MHz by using a resistor tied from the RT pin to ground. Table 2 provides a list of RT resistor values and their resultant frequencies. 8050fc For more information www.linear.com/LTM8050 LTM8050 APPLICATIONS INFORMATION Table 1: Recommended Component Values and Configuration (TA = 25C) VIN RANGE VOUT VBIAS CIN COUT RFB fOPTIMAL RT(OPTIMAL) fMAX RT(MIN) 3.6V to 58V 0.8V 2.8V to 25V 3x 4.7F, 2220, 100V 3x 220F, 1206, 4V Open 110kHz 392k 125kHz 340k 3.6V to 58V 1V 2.8V to 25V 3x 4.7F, 2220, 100V 3x 220F, 1206, 4V 1.87M 110kHz 392k 125kHz 340k 3.6V to 58V 1.2V 2.8V to 25V 2x 4.7F, 2220, 100V 3x 220F, 1206, 4V 953k 125kHz 340k 150kHz 280k 3.6V to 58V 1.5V 2.8V to 25V 2x 4.7F, 2220, 100V 2x 220F, 1206, 4V 549k 150kHz 280k 180kHz 232k 3.6V to 58V 1.8V 2.8V to 25V 2x 4.7F, 2220, 100V 2x 220F, 1206, 4V 383k 180kHz 232k 215kHz 191k 4.1V to 58V 2.5V 2.8V to 25V 4.7F, 2220, 100V 220F, 1206, 4V 226k 230kHz 174k 270kHz 150k 5.3V to 58V 3.3V AUX 4.7F, 2220, 100V 220F, 1206, 4V 154k 280kHz 140k 330kHz 118k 7.5V to 58V 5V AUX 4.7F, 2220, 100V 100F, 1210, 6.3V 93.1k 400kHz 93.1k 460kHz 80.6k 10.5V to 58V 8V AUX 4.7F, 2220, 100V 47F, 1210, 10V 54.9k 550kHz 64.9k 690kHz 49.9k 17V to 58V 12V AUX 4.7F, 2220, 100V 22F, 1210, 16V 34.8k 600kHz 57.6k 750kHz 44.2k 24V to 58V 18V 2.8V to 25V 4.7F, 2220, 100V 22F, 1812, 25V 22.6k 760kHz 42.2k 850kHz 37.4k 34V to 58V 24V 2.8V to 25V 4.7F, 2220, 100V 22F, 1812, 25V 16.5k 900kHz 33.2k 960kHz 30.1k 9V to 24V 0.8V VIN 4.7F, 1206, 25V 2x 220F, 1206, 4V Open 150kHz 280k 300kHz 130k 9V to 24V 1V VIN 4.7F, 1206, 25V 2x 220F, 1206, 4V 1.87M 180kHz 232k 345kHz 113k 9V to 24V 1.2V VIN 4.7F, 1206, 25V 2x 220F, 1206, 4V 953k 230kHz 174k 400kHz 93.1k 9V to 24V 1.5V VIN 4.7F, 1206, 25V 220F, 1206, 4V 549k 280kHz 140k 460kHz 80.6k 9V to 24V 1.8V VIN 4.7F, 1206, 25V 220F, 1206, 4V 383k 330kHz 118k 500kHz 73.2k 9V to 24V 2.5V VIN 4.7F, 1206, 25V 100F, 1210, 6.3V 226k 345kHz 113k 600kHz 57.6k 9V to 24V 3.3V AUX 4.7F, 1206, 25V 100F, 1210, 6.3V 154k 425kHz 88.7k 650kHz 52.3k 9V to 24V 5V AUX 4.7F, 1206, 25V 47F, 1210, 10V 93.1k 500kHz 73.2k 700kHz 48.7k 10.5V to 24V 8V AUX 4.7F, 1206, 25V 47F, 1210, 10V 54.9k 600kHz 57.6k 750kHz 44.2k 17V to 24V 12V AUX 2.2F, 1206, 50V 22F, 1210, 16V 34.8k 760kHz 42.2k 850kHz 36.5k 18V to 36V 0.8V 2.8V to 25V 1F, 1206, 50V 3x 220F, 1206, 4V Open 100kHz 432k 200kHz 205k 18V to 36V 1V 2.8V to 25V 1F, 1206, 50V 3x 220F, 1206, 4V 1.87M 120kHz 357k 250kHz 162k 18V to 36V 1.2V 2.8V to 25V 1F, 1206, 50V 2x 220F, 1206, 4V 953k 140kHz 301k 270kHz 150k 18V to 36V 1.5V 2.8V to 25V 1F, 1206, 50V 2x 220F, 1206, 4V 549k 180kHz 232k 300kHz 130k 18V to 36V 1.8V 2.8V to 25V 1F, 1206, 50V 220F, 1206, 4V 383k 220kHz 187k 350kHz 110k 18V to 36V 2.5V 2.8V to 25V 1F, 1206, 50V 100F, 1210, 6.3V 226k 300kHz 130k 425kHz 88.7k 18V to 36V 3.3V AUX 1F, 1206, 50V 100F, 1210, 6.3V 154k 345kHz 113k 550kHz 64.9k 18V to 36V 5V AUX 1F, 1206, 50V 47F, 1210, 10V 93.1k 425kHz 88.7k 800kHz 38.3k 18V to 36V 8V AUX 2.2F, 1206, 50V 22F, 1210, 16V 54.9k 550kHz 64.9k 1.03MHz 25.5k 18V to 36V 12V AUX 2.2F, 1206, 50V 22F, 1210, 16V 34.8k 760kHz 42.2k 1.03MHz 25.5k 24V to 36V 18V 2.8V to 25V 2.2F, 1206, 50V 22F, 1812, 25V 22.6k 800kHz 38.3k 1.03MHz 25.5k 18V to 58V 0.8V 2.8V to 25V 1F, 1206, 100V 3x 220F, 1206, 4V Open 100kHz 432k 125kHz 340k 18V to 58V 1V 2.8V to 25V 1F, 1206, 100V 3x 220F, 1206, 4V 1.87M 100kHz 432k 125kHz 340k 18V to 58V 1.2V 2.8V to 25V 1F, 1206, 100V 3x 220F, 1206, 4V 953k 100kHz 432k 150kHz 280k 18V to 58V 1.5V 2.8V to 25V 1F, 1206, 100V 2x 220F, 1206, 4V 549k 110kHz 392k 180kHz 232k 18V to 58V 1.8V 2.8V to 25V 1F, 1206, 100V 2x 220F, 1206, 4V 383k 125kHz 340k 215kHz 191k 18V to 58V 2.5V 2.8V to 25V 1F, 1206, 100V 220F, 1206, 4V 226k 180kHz 232k 270kHz 150k 18V to 58V 3.3V AUX 1F, 1206, 100V 100F, 1210, 6.3V 154k 280kHz 140k 330kHz 118k 18V to 58V 5V AUX 1F, 1206, 100V 100F, 1210, 6.3V 93.1k 400kHz 93.1k 460kHz 80.6k 18V to 58V 8V AUX 2.2F, 1206, 100V 47F, 1210, 10V 54.9k 550kHz 64.9k 690kHz 49.9k 18V to 58V 12V AUX 2.2F, 1206, 100V 22F, 1210, 16V 34.8k 600kHz 57.6k 960kHz 30.1k 2.5V to 54.7V -3.3V AUX 2x 4.7F, 2220, 100V 100F, 1210, 6.3V 154k 300kHz 130k 330kHz 118k 3.3V to 53V -5V AUX 4.7F, 2220, 100V 100F, 1210, 6.3V 93.1k 400kHz 93.1k 460kHz 80.6k 3.3V to 50V -8V AUX 4.7F, 2220, 100V 47F, 1210, 10V 54.9k 550kHz 64.9k 690kHz 49.9k 4.5V to 46V -12V AUX 4.7F, 2220, 100V 47F, 1210, 16V 34.8k 600kHz 57.6k 750kHz 44.2k 6V to 40V -18V 2.8V to 25V 4.7F, 2220, 100V 22F, 1812, 25V 22.6k 760kHz 42.2k 850kHz 37.4k 10V to 34V -24V 2.8V to 25V 4.7F, 2220, 100V 22F, 1812, 25V 16.5k 900kHz 33.2k 960kHz 30.1k Note: Do not allow VIN + BIAS to exceed 72V. 8050fc For more information www.linear.com/LTM8050 13 LTM8050 APPLICATIONS INFORMATION Table 2. Switching Frequency vs RT Value SWITCHING FREQUENCY (MHz) RT VALUE (k) 0.1 432 0.2 215 0.3 137 0.4 93.1 0.5 73.2 0.6 57.6 0.7 51.1 0.8 38.3 0.9 33.2 1 32.4 1.2 24.9 1.4 20 1.6 16.2 1.8 14 2 11 2.2 8.06 2.4 7.15 Operating Frequency Trade-offs It is recommended that the user apply the optimal RT value given in Table 1 for the input and output operating condition. System level or other considerations, however, may necessitate another operating frequency. While the LTM8050 is flexible enough to accommodate a wide range of operating frequencies, a haphazardly chosen one may result in undesirable operation under certain operating or fault conditions. A frequency that is too high can reduce efficiency, generate excessive heat or even damage the LTM8050 if the output is overloaded or short circuited. A frequency that is too low can result in a final design that has too much output ripple or too large of an output capacitor. BIAS Pin Considerations The BIAS pin is used to provide drive power for the internal power switching stage and operate other internal circuitry. For proper operation, it must be powered by at least 2.8V. If the output voltage is programmed to 2.8V or higher, BIAS may be simply tied to AUX. If VOUT is less than 2.8V, BIAS can be tied to VIN or some other voltage source. If the BIAS pin voltage is too high, the efficiency of the LTM8050 may suffer. The optimum BIAS voltage is dependent upon many 14 factors, such as load current, input voltage, output voltage and switching frequency, but 4V to 5V works well in many applications. In all cases, ensure that the maximum voltage at the BIAS pin is less than 25V and that the sum of VIN and BIAS is less than 72V. If BIAS power is applied from a remote or noisy voltage source, it may be necessary to apply a decoupling capacitor locally to the pin. Load Sharing Two or more LTM8050's may be paralleled to produce higher currents. To do this, tie the VIN, FB, VOUT and SHARE pins of all the paralleled LTM8050's together. To ensure that paralleled modules start up together, the RUN/SS pins may be tied together, as well. If the RUN/SS pins are not tied together, make sure that the same valued soft-start capacitors are used for each module. Current sharing can be improved by synchronizing the LTM8050s. An example of two LTM8050s configured for load sharing is given in the Typical Applications section. When n number of units are connected for parallel operation and a single feedback resistor is used for all of them, the equation for the feedback resistor is: RFB = 394.21 k N( VOUT - 0.79 ) Burst Mode Operation To enhance efficiency at light loads, the LTM8050 automatically switches to Burst Mode operation which keeps the output capacitor charged to the proper voltage while minimizing the input quiescent current. During Burst Mode operation, the LTM8050 delivers single cycle bursts of current to the output capacitor followed by sleep periods where the output power is delivered to the load by the output capacitor. In addition, VIN and BIAS quiescent currents are each reduced to microamps during the sleep time. As the load current decreases towards a no load condition, the percentage of time that the LTM8050 operates in sleep mode increases and the average input current is greatly reduced, resulting in higher efficiency. Burst Mode operation is enabled by tying SYNC to GND. To disable Burst Mode operation, tie SYNC to a stable voltage above 0.7V. Do not leave the SYNC pin floating. 8050fc For more information www.linear.com/LTM8050 LTM8050 APPLICATIONS INFORMATION Minimum Input Voltage The LTM8050 is a step-down converter, so a minimum amount of headroom is required to keep the output in regulation. In addition, the input voltage required to turn on is higher than that required to run, and depends upon whether the RUN/SS is used. As shown in the Typical Performance Characteristics section, the minimum input voltage to run a 3.3V output at light load is only about 3.6V, but, if RUN/SS is pulled up to VIN, it takes 5.5VIN to start. If the LTM8050 is enabled with the RUN/SS pin after VIN is applied, the minimum voltage to start at light loads is lower, about 4.3V. Similar curves detailing this behavior of the LTM8050 for other outputs are also included in the Typical Performance Characteristics section. Soft-Start The RUN/SS pin can be used to soft-start the LTM8050, reducing the maximum input current during start-up. The RUN/SS pin is driven through an external RC network to create a voltage ramp at this pin. (See Figure 1). By choosing an appropriate RC time constant, the peak start-up current can be reduced to the current that is required to regulate the output, with no overshoot. Choose the value of the resistor so that it can supply at least 20A when the RUN/SS pin reaches 2.5V. Output voltage soft-start waveforms for various values of RSS and CSS are given in the Typical Performance Characteristics section. RUN 100k RUN/SS CSS RUN Figure 1. Apply an RC Network to RUN/SS to Control the Soft-Start Behavior of the LTM8050 at Power-Up Frequency Foldback The LTM8050 is equipped with frequency foldback which acts to reduce the thermal and energy stress on the internal power elements during a short circuit or output overload condition. If the LTM8050 detects that the output has fallen out of regulation, the switching frequency is reduced as a function of how far the output is below the target voltage. This in turn limits the amount of energy that can be delivered to the load under fault. During the start-up time, frequency foldback is also active to limit the energy delivered to the potentially large output capacitance of the load. Synchronization The internal oscillator of the LTM8050 can be synchronized by applying an external 250kHz to 2MHz clock to the SYNC pin. Do not leave this pin floating. When synchronizing the LTM8050, select an RT resistor value that corresponds to an operating frequency 20% lower than the intended synchronization frequency (see the Frequency Selection section). In addition to synchronization, the SYNC pin controls Burst Mode behavior. If the SYNC pin is driven by an external clock, or pulled up above 0.7V, the LTM8050 will not enter Burst Mode operation, but will instead skip pulses to maintain regulation instead. Shorted Input Protection Care needs to be taken in systems where the output will be held high when the input to the LTM8050 is absent. This may occur in battery charging applications or in battery backup systems where a battery or some other supply is diode ORed with the LTM8050's output. If the VIN pin is allowed to float and the SHDN pin is held high (either by a logic signal or because it is tied to VIN), then the LTM8050's internal circuitry will pull its quiescent current through its internal power switch. This is fine if your system can tolerate a few milliamps in this state. If you ground the RUN/SS pin, the input current will drop to essentially zero. However, if the VIN pin is grounded while the output is held high, then parasitic diodes inside the LTM8050 can pull large currents from the output through the VIN pin. Figure 2 shows a circuit that will run only when the input voltage is present and that protects against a shorted or reversed input. PCB Layout Most of the headaches associated with PCB layout have been alleviated or even eliminated by the high level of integration of the LTM8050. The LTM8050 is nevertheless a switching power supply, and care must be taken to 8050fc For more information www.linear.com/LTM8050 15 LTM8050 APPLICATIONS INFORMATION VIN VIN VOUT VOUT RUN/SS AUX LTM8050 RT AUX GND PGOOD RT RFB GND BIAS SYNC FB SYNC RUN/SS GND BIAS VOUT VIN 8050 F02 Figure 2. The Input Diode Prevents a Shorted Input from Discharging a Backup Battery Tied to the Output. It Also Protects the Circuit from a Reversed Input. The LTM8050 Runs Only When the Input is Present minimize EMI and ensure proper operation. Even with the high level of integration, you may fail to achieve specified operation with a haphazard or poor layout. See Figure 3 for a suggested layout. Ensure that the grounding and heat sinking are acceptable. 1. Place the RFB and RT resistors as close as possible to their respective pins. 2. Place the CIN capacitor as close as possible to the VIN and GND connection of the LTM8050. 3. Place the COUT capacitor as close as possible to the VOUT and GND connection of the LTM8050. 4. Place the CIN and COUT capacitors such that their ground current flow directly adjacent to or underneath the LTM8050. 5. Connect all of the GND connections to as large a copper pour or plane area as possible on the top layer. Avoid breaking the ground connection between the external components and the LTM8050. 6. For good heat sinking, use vias to connect the GND copper area to the board's internal ground planes. Liberally distribute these GND vias to provide both a good ground connection and thermal path to the internal planes of the printed circuit board. Pay attention to the location and density of the thermal vias in Figure 3. The LTM8050 can benefit from the heat-sinking afforded by vias that connect to internal GND planes at these locations, due to their proximity to internal power handling components. The optimum number of thermal vias depends upon the printed circuit board design. For example, a board 16 CIN COUT GND THERMAL VIAS TO GND 8050 F03 Figure 3. Layout Showing Suggested External Components, GND Plane and Thermal Vias might use very small via holes. It should employ more thermal vias than a board that uses larger holes. Hot-Plugging Safely The small size, robustness and low impedance of ceramic capacitors make them an attractive option for the input bypass capacitor of LTM8050. However, these capacitors can cause problems if the LTM8050 is plugged into a live supply (see Linear Technology Application Note 88 for a complete discussion). The low loss ceramic capacitor combined with stray inductance in series with the power source forms an underdamped tank circuit, and the voltage at the VIN pin of the LTM8050 can ring to more than twice the nominal input voltage, possibly exceeding the LTM8050's rating and damaging the part. If the input supply is poorly controlled or the user will be plugging the LTM8050 into an energized supply, the input network should be designed to prevent this overshoot. This can be accomplished by installing a small resistor in series to VIN, but the most popular method of controlling input voltage overshoot is to add an electrolytic bulk capacitor to the VIN net. This capacitor's relatively high equivalent series resistance damps the circuit and eliminates the voltage overshoot. The extra capacitor improves low frequency ripple filtering and can slightly improve the efficiency of the circuit, though it is likely to be the largest component in the circuit. 8050fc For more information www.linear.com/LTM8050 LTM8050 APPLICATIONS INFORMATION Negative Output Considerations The LTM8050 may be configured to generate a negative output voltage. Examples of this are shown in the Typical Applications section. For very fast rising input voltages, care must be taken to ensure that start-up does not create excessive surge currents that may create unwanted voltages or even damage the LTM8050. Consider the circuit in Figure 4. If a step input is applied between VIN and system GND, the CIN and COUT capacitors form an AC divider network that tends to create a positive voltage on system VOUT. In order to protect the load from seeing an excessive inverted voltage, an antiparallel Schottky diode may be used to clamp the voltage. Furthermore, current flowing out of the BIAS pin can have adverse affects. To prevent this from happening, apply a series resistor (about 200) and Schottky diode between BIAS and its voltage source. Thermal Considerations The LTM8050 output current may need to be derated if it is required to operate in a high ambient temperature or deliver a large amount of continuous power. The amount of current derating is dependent upon the input voltage, output power and ambient temperature. The temperature rise curves given in the Typical Performance Characteristics section can be used as a guide. These curves were generated by a LTM8050 mounted to a 40cm2 4-layer FR4 printed circuit board. Boards of other sizes and layer count can exhibit different thermal behavior, so it is incumbent upon the user to verify proper operation over the intended system's line, load and environmental operating conditions. The thermal resistance numbers listed in Page 2 of the data sheet are based on modeling the Module package mounted on a test board specified per JESD51-9 (Test Boards for Area Array Surface Mount Package Thermal Measurements). The thermal coefficients provided in this page are based on JESD 51-12 (Guidelines for Reporting and Using Electronic Package Thermal Information). For increased accuracy and fidelity to the actual application, many designers use FEA to predict thermal performance. To that end, Page 2 of the data sheet typically gives four thermal coefficients: JA - Thermal resistance from junction to ambient JCbottom - Thermal resistance from junction to the bottom of the product case JCtop - Thermal resistance from junction to top of the product case JB - Thermal resistance from junction to the printed circuit board While the meaning of each of these coefficients may seem to be intuitive, JEDEC has defined each to avoid confusion and inconsistency. These definitions are given in JESD 51-12, and are quoted or paraphrased below: JA is the natural convection junction-to-ambient air thermal resistance measured in a one cubic foot sealed enclosure. This environment is sometimes referred to as ADD A SERIES RESISTOR AND DIODE TO PREVENT CURRENT FROM FLOWING OUT OF BIAS VIN VIN VOUT RUN/SS AUX LTM8050 BIAS CIN SHARE RT SYNC PGOOD GND ADJ COUT INRUSH CURRENT CAN CAUSE A POSITIVE TRANSIENT ON VOUT ADD AN ANTI-PARALLEL DIODE TO CLAMP POSITIVE VOLTAGE SPIKE VOUT (NEGATIVE VOLTAGE) 8050 F04 Figure 4. In Negative Output Voltage Applications, Prevent Adverse Effects from Fast Rising VIN by Adding Clamp and Rectifying Diodes 8050fc For more information www.linear.com/LTM8050 17 LTM8050 APPLICATIONS INFORMATION still air although natural convection causes the air to move. This value is determined with the part mounted to a JESD 51-9 defined test board, which does not reflect an actual application or viable operating condition. JCbottom is the thermal resistance between the junction and bottom of the package with all of the component power dissipation flowing through the bottom of the package. In the typical Module converter, the bulk of the heat flows out the bottom of the package, but there is always heat flow out into the ambient environment. As a result, this thermal resistance value may be useful for comparing packages but the test conditions don't generally match the user's application. JCtop is determined with nearly all of the component power dissipation flowing through the top of the package. As the electrical connections of the typical Module converter are on the bottom of the package, it is rare for an application to operate such that most of the heat flows from the junction to the top of the part. As in the case of JCbottom, this value may be useful for comparing packages but the test conditions don't generally match the user's application. JB is the junction-to-board thermal resistance where almost all of the heat flows through the bottom of the Module converter and into the board, and is really the sum of the JCbottom and the thermal resistance of the bottom of the part through the solder joints and through a portion of the board. The board temperature is measured a specified distance from the package, using a two sided, two layer board. This board is described in JESD 51-9. Given these definitions, it should now be apparent that none of these thermal coefficients reflects an actual physical operating condition of a Module converter. Thus, none of them can be individually used to accurately predict the thermal performance of the product. Likewise, it would be inappropriate to attempt to use any one coefficient to correlate to the junction temperature vs load graphs given in the product's data sheet. The only appropriate way to use the coefficients is when running a detailed thermal analysis, such as FEA, which considers all of the thermal resistances simultaneously. A graphical representation of these thermal resistances follows: The blue resistances are contained within the Module converter, and the green are outside. The die temperature of the LTM8050 must be lower than the maximum rating of 125C, so care should be taken in the layout of the circuit to ensure good heat sinking of the LTM8050. The bulk of the heat flow out of the LTM8050 is through the bottom of the Module converter and the LGA pads into the printed circuit board. Consequently a poor printed circuit board design can cause excessive heating, resulting in impaired performance or reliability. Please refer to the PCB Layout section for printed circuit board design suggestions. JUNCTION-TO-AMBIENT RESISTANCE (JESD 51-9 DEFINED BOARD) JUNCTION-TO-CASE (TOP) RESISTANCE JUNCTION CASE (TOP)-TO-AMBIENT RESISTANCE JUNCTION-TO-BOARD RESISTANCE JUNCTION-TO-CASE CASE (BOTTOM)-TO-BOARD (BOTTOM) RESISTANCE RESISTANCE At BOARD-TO-AMBIENT RESISTANCE 8050 F04 MODULE DEVICE 18 8050fc For more information www.linear.com/LTM8050 LTM8050 TYPICAL APPLICATIONS 1.8V Step-Down Converter VIN 3.6V TO 58V VIN RUN/SS 10F 3.3V AUX 440F LTM8050 BIAS SHARE PGOOD RT FB SYNC 232k f = 180kHz VOUT 1.8V AT 2A VOUT GND 383k 8050 TA02 2.5V Step-Down Converter VIN* 4.1V TO 58V VIN 3.3V AUX SHARE VIN* 11V TO 58V VIN 220F LTM8050 BIAS 4.7F PGOOD RT GND *RUNNING VOLTAGE RANGE. PLEASE REFER TO APPLICATIONS INFORMATION SECTION FOR START-UP DETAILS 8050 TA03 VIN BIAS PGOOD RT 47F FB SYNC GND PGOOD 47F FB SYNC GND 54.9k 8050 TA04 RUNNING TO START, RUN CONTROL TO START, RUN = VIN 20 AUX LTM8050 SHARE 93.1k f = 400kHz 25 93.1k 8050 TA05 VOUT -5V MINIMUM VIN (V) 4.7F BIAS Minimum VIN vs Output Current -5VOUT, BIAS = GND VOUT RUN/SS AUX LTM8050 *RUNNING VOLTAGE RANGE. PLEASE REFER TO APPLICATIONS INFORMATION SECTION FOR START-UP DETAILS -5V Negative Output Converter VIN RUN/SS RT 64.9k f = 550kHz 226k VOUT 8V AT 2A VOUT SHARE FB SYNC 174k f = 230kHz VOUT 2.5V AT 2A VOUT RUN/SS 4.7F 8V Step-Down Converter 15 10 5 0 0 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 8050 TA05b 8050fc For more information www.linear.com/LTM8050 19 LTM8050 TYPICAL APPLICATIONS Two LTM8050s in Parallel, 2.5V at 3.8A VIN* 4.1V TO 58V VIN VOUT 2.5V AT 3.8A VOUT RUN/SS AUX LTM8050 SHARE BIAS 3V PGOOD 10F RT FB SYNC 174k 230kHz GND 113k OPTIONAL SYNC VIN VOUT RUN/SS AUX LTM8050 SHARE 300F BIAS PGOOD 10F RT FB SYNC 174k 230kHz GND *RUNNING VOLTAGE RANGE. PLEASE REFER TO APPLICATIONS INFORMATION SECTION FOR START-UP DETAILS NOTE: SYNCHRONIZE THE TWO MODULES TO AVOID BEAT FREQUENCIES, IF NECESSARY. OTHERWISE, TIE EACH SYNC TO GND 8050 TA06 3.3V Step-Down Converter VIN* 5.3V TO 58V VIN 4.7F RUN/SS AUX LTM8050 SHARE BIAS PGOOD RT 140k f = 280kHz VOUT 3.3V AT 2A VOUT 220F FB SYNC GND 154k *RUNNING VOLTAGE RANGE. PLEASE REFER TO APPLICATIONS INFORMATION SECTION FOR START-UP DETAILS 20 8050 TA07 8050fc For more information www.linear.com/LTM8050 LTM8050 PACKAGE DESCRIPTION PACKAGE ROW AND COLUMN LABELING MAY VARY AMONG Module PRODUCTS. REVIEW EACH PACKAGE LAYOUT CAREFULLY. Pin Assignment Table (Arranged by Pin Number) PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME A1 VOUT B1 VOUT C1 VOUT D1 VOUT E1 GND F1 GND A2 VOUT A3 VOUT B2 VOUT B3 VOUT C2 VOUT C3 VOUT D2 VOUT D3 VOUT E2 GND F2 GND E3 GND F3 GND A4 VOUT B4 VOUT C4 VOUT D4 VOUT E4 GND F4 GND A5 GND B5 GND C5 GND D5 GND E5 GND F5 GND A6 GND B6 GND C6 GND D6 GND E6 GND F6 GND A7 GND B7 GND C7 GND D7 GND E7 GND F7 GND PIN NAME PIN NAME PIN NAME PIN NAME K1 VIN K2 VIN PIN NAME L1 VIN L2 VIN G1 GND H1 - J1 VIN G2 GND H2 - J2 VIN G3 GND H3 - J3 VIN K3 VIN L3 VIN G4 GND H4 - J4 - K4 - L4 - G5 AUX H5 BIAS J5 GND K5 GND L5 RUN/SS G6 GND H6 GND J6 GND K6 GND L6 SYNC G7 RT H7 SHARE J7 PGOOD K7 FB L7 GND 8050fc For more information www.linear.com/LTM8050 21 0.630 0.025 O 70x E PACKAGE TOP VIEW SUGGESTED PCB LAYOUT TOP VIEW 2.540 4 1.270 PIN "A1" CORNER 0.3175 0.000 0.3175 aaa Z 1.270 Y 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. For more information www.linear.com/LTM8050 6.350 5.080 3.810 2.540 1.270 0.000 1.270 2.540 3.810 5.080 6.350 D X aaa Z SYMBOL A A1 A2 b b1 D E e F G H1 H2 aaa bbb ccc ddd eee H1 SUBSTRATE A1 NOM 4.92 0.60 4.32 0.75 0.63 15.00 9.00 1.27 12.70 7.62 0.32 4.00 DIMENSIONS b1 A A2 MAX 5.12 0.70 4.42 0.90 0.66 NOTES DETAIL B PACKAGE SIDE VIEW 0.37 4.05 0.15 0.10 0.20 0.30 0.15 TOTAL NUMBER OF BALLS: 70 0.27 3.95 MIN 4.72 0.50 4.22 0.60 0.60 DETAIL A ddd M Z X Y eee M Z DETAIL B H2 MOLD CAP ccc Z Ob (70 PLACES) // bbb Z Z (Reference LTC DWG# 05-08-1918 Rev A) Z 22 2.540 BGA Package 70-Lead (15mm x 9mm x 4.92mm) F e 7 5 4 3 2 1 DETAIL A PACKAGE BOTTOM VIEW 6 G L K J H G F E D C B A PIN 1 DETAILS OF PIN #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE PIN #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE 4 TRAY PIN 1 BEVEL COMPONENT PIN "A1" 7 ! BGA 70 1212 REV A PACKAGE IN TRAY LOADING ORIENTATION LTMXXXXXX Module PACKAGE ROW AND COLUMN LABELING MAY VARY AMONG Module PRODUCTS. REVIEW EACH PACKAGE LAYOUT CAREFULLY 6. SOLDER BALL COMPOSITION IS 96.5% Sn/3.0% Ag/0.5% Cu 5. PRIMARY DATUM -Z- IS SEATING PLANE BALL DESIGNATION PER JESD MS-028 AND JEP95 3 2. ALL DIMENSIONS ARE IN MILLIMETERS 7 SEE NOTES NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994 b 3 SEE NOTES LTM8050 Please refer to http://www.linear.com/product/LTM8050#packaging for the most recent package drawings. PACKAGE DESCRIPTION 8050fc 3.810 3.810 LTM8050 REVISION HISTORY REV DATE DESCRIPTION A 02/14 Add SnPb BGA package option B 05/14 C 10/16 PAGE NUMBER 1, 2 Add TechClip Video icons 1 Correct Typical Performance Characteristics labels 8 Corrected BIAS voltage from 33V to 3.3V (top of page) 19 8050fc For more information www.linear.com/LTM8050 23 LTM8050 PACKAGE PHOTO RELATED PARTS PART NUMBER DESCRIPTION COMMENTS Pin Compatible; Remote Sensing; PLL, Tracking and Margining, 4.5V VIN 28V LTM4601/LTM4603 12A and 6A DC/DC Module 4A, Low VIN DC/DC Module LTM4604A 2.375V VIN 5.5V, 0.8V VOUT 5V, 9mm x 15mm x 2.3mm LGA Package LTM4606 Low EMI 6A, 28V DC/DC Module 4.5V VIN 28V, 0.6V VOUT 5V, 15mm x 15mm x 2.8mm LGA Package LTM8020 200mA, 36V DC/DC Module 4V VIN 36V, 1.25V VOUT 5V, 6.25mm x 6.25mm x 2.32mm LGA Package LTM8022/LTM8023 1A and 2A, 36V DC/DC Module Pin Compatible 3.6V VIN 36V, 0.8V VOUT 10V, 11.25mm x 9mm x 2.82mm LGA Package LTM8027 4.5V VIN 60V; 2.5V VOUT 24V, 15mm x 15mm x 4.32mm LGA Package 60V, 4A DC/DC Module DESIGN RESOURCES SUBJECT DESCRIPTION Module Design and Manufacturing Resources Design: * Selector Guides * Demo Boards and Gerber Files * Free Simulation Tools Module Regulator Products Search Manufacturing: * Quick Start Guide * PCB Design, Assembly and Manufacturing Guidelines * Package and Board Level Reliability 1. Sort table of products by parameters and download the result as a spread sheet. 2. Search using the Quick Power Search parametric table. TechClip Videos Quick videos detailing how to bench test electrical and thermal performance of Module products. Digital Power System Management Linear Technology's family of digital power supply management ICs are highly integrated solutions that offer essential functions, including power supply monitoring, supervision, margining and sequencing, and feature EEPROM for storing user configurations and fault logging. 24 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LTM8050 (408) 432-1900 FAX: (408) 434-0507 www.linear.com/LTM8050 8050fc LT 1016 REV C * PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 2013