LTM8028 36VIN, UltraFast, Low Output Noise 5A µModule Regulator FEATURES DESCRIPTION High Performance 5A Linear Regulator with Switching Step-Down Converter for High Efficiency n Digitally Programmable V OUT: 0.8V to 1.8V n Input Voltage Range: 6V to 36V n Very Tight Tolerance Over Temperature, Line, Load and Transient Response n Low Output Noise: 40μV RMS (10Hz to 100kHz) n Parallel Multiple Devices for 10A or More n Accurate Programmable Current Limit to Allow Asymmetric Power Sharing n Analog Output Margining: ±10% Range n Synchronization Input n Stable with Low ESR Ceramic Output Capacitors n15mm × 15mm × 4.92mm Surface Mount BGA Package The LTM®8028 is a 36VIN, 5A µModule® regulator, consisting of an UltraFast™ 5A linear regulator preceded by a high efficiency switching regulator. In addition to providing tight output regulation, the linear regulator automatically controls the output voltage of the switcher to provide optimal efficiency and headroom for dynamic response. n APPLICATIONS n n n n The output voltage is digitally selectable in 50mV increments over a 0.8V to 1.8V range. An analog margining function allows the user to adjust system output voltage over a continuous ±10% range, and a single-ended feedback sense line may be used to mitigate IR drops due to parasitic resistance. The LTM8028 is packaged in a compact (15mm × 15mm × 4.92mm) overmolded ball grid array (BGA) package suitable for automated assembly by standard surface mount equipment. The LTM8028 is RoHS compliant. L, LT, LTC, LTM, µModule, Linear Technology and the Linear logo are registered trademarks and UltraFast is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. 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TYPICAL APPLICATION Low Output Noise, 1.2V, 5A µModule Regulator VIN 9V TO 15V LTM8028 VIN 150k 10µF 0.01µF RUN MARGA IMAX VOUT LINEAR REGULATOR SENSEP BKV SS 82.5k RT f = 500kHz VOUT 1.2V 5A PGOOD SYNC GND VOB VO0 VO1 VO2 137µF + VOUT 20mV/DIV IOUT 2A/DIV ∆IOUT = 0.5A TO 5A 1µs RISE/FALL TIME 10µs/DIV 100µF 470µF 8028 TA01a FULL LOAD NOISE AND RIPPLE 500µV/DIV 1µs/DIV MEASURED PER AN70, 150MHz BW 8028 TA01b 8028f For more information www.linear.com/LTM8028 1 LTM8028 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Notes 1, 4) VIN.............................................................................40V VOUT.............................................................................3V RUN, SS, SYNC ...........................................................6V Current Into RUN...................................................100μA VOB, VO0, VO1, VO2, TEST, PGOOD, SENSEP, MARGA............................................4V RT, BKV, IMAX..............................................................3V Maximum Operating Junction Temperature (Note 2).................................................................. 125°C Maximum Body Reflow Temperature..................... 240°C Maximum Storage Temperature............................. 125°C TOP VIEW 11 BANK 1 10 SENSEP TEST PGOOD VO1 VOB MARGA VO0 VO2 BANK 2 VOUT BKV 9 8 7 BANK 3 6 GND 5 4 3 2 SS SYNC 1 BANK 4 VIN IMAX RT RUN A B C D E F G H J K L BGA PACKAGE 114 PADS (15mm × 15mm × 4.92mm) TJMAX = 125°C, θJA = 17.7°C/W, θJB = 6.0°C/W, θJCtop = 15°C/W, θJCbottom = 6.0°C/W θ VALUES DETERMINED PER JEDEC 51-9, 51-12 WEIGHT = 1.8 GRAMS ORDER INFORMATION LEAD FREE FINISH TRAY PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE (NOTE 2) LTM8028EY#PBF LTM8028EY#PBF LTM8028Y 114-Lead (15mm × 15mm × 4.92mm) BGA –40°C to 125°C LTM8028IY#PBF LTM8028IY#PBF LTM8028Y 114-Lead (15mm × 15mm × 4.92mm) BGA –40°C to 125°C LTM8028MPY#PBF LTM8028MPY#PBF LTM8028Y 114-Lead (15mm × 15mm × 4.92mm) BGA –55°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. 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://www.linear.com/packaging/ ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full internal operating temperature range, otherwise specifications are at TA = 25°C. VIN = 12V, RUN = 3V unless otherwise noted. (Note 2) PARAMETER CONDITIONS MIN TYP Minimum Input Voltage Output DC Voltage l l l l l Output DC Current VOUT = 1.8V Quiescent Current Into VIN RUN = 0V No load 0.788 0.985 1.182 1.477 1.773 0.8 1.0 1.2 1.5 1.8 MAX V 0.812 1.015 1.218 1.523 1.827 V V V V V 5 1 35 UNITS 6 A µA mA 8028f 2 For more information www.linear.com/LTM8028 LTM8028 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full internal operating temperature range, otherwise specifications are at TA = 25°C. VIN = 12V, RUN = 3V unless otherwise noted. (Note 2) PARAMETER CONDITIONS MIN Line Regulation 6V < VIN < 36V, IOUT = 10mA Load Regulation 0.01A < IOUT < 5A, VOUT = 0.8V, BKV = 1.05V, RUN = 0V TYP mV –1.5 –3 –5.5 mV mV –2 –4 –7.5 mV mV –2 –4 –7.5 mV mV –2.5 –5 –9 mV mV –3 –7 –13 mV mV l l 0.01A < IOUT < 5A, VOUT = 1.2V, BKV = 1.45V, RUN = 0V l 0.01A < IOUT < 5A, VOUT = 1.5V, BKV = 1.75V, RUN = 0V l 0.01A < IOUT < 5A, VOUT = 1.8V, BKV = 2.05V, RUN = 0V UNITS 1 l 0.01A < IOUT < 5A, VOUT = 1.0V, BKV = 1.25V, RUN = 0V MAX l Sense Pin Current VOUT = 0.8V VOUT = 1.8V 50 300 µA µA Switching Frequency RT = 40.2k RT = 200k 1000 200 kHz kHz RUN Pin Current RUN = 1.45V 5.5 µA RUN Threshold Voltage (Falling) l 1.49 RUN Input Hysteresis IMAX Pin Current IMAX = 0.75V IMAX Current Limit Accuracy IMAX = 1.5V IMAX = 0.75V 1.55 130 mV µA 6.1 3.6 11 SYNC Input Threshold fSYNC = 500kHz SYNC Bias Current SYNC = 0V 0.8 VOB Voltage VOB = 3.3V l VOx Input High Threshold VOB = 3.3V l 3.05 VOx Input Z Range VOB = 3.3V l 0.75 A A µA 1.2 V 1 µA 3.3 VOx Input Low Threshold V 125 5.0 2.20 SS Pin Current 1.61 V 0.25 V V VOx Input Current High VOx Input Current Low 2.4 V 40 µA 40 µA MARGA Pin Current MARGA = 0V 3.5 μA PGOOD Theshold VOUT(NOMINAL) = 1.0V, VOUT Rising VOUT(NOMINAL) = 1.0V, VOUT Falling 0.9 0.85 V V Output Voltage Noise (Note 3) VOUT = 1.8V, COUT = 137µF, 5A Load, BW = 10Hz to 100kHz 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 LTM8028E is guaranteed to meet performance specifications from 0°C to 125°C internal. Specifications over the full –40°C to 125°C internal operating temperature range are assured by design, characterization and correlation with statistical process controls. The LTM8028I is guaranteed to meet specifications over the full –40°C to 125°C internal operating temperature range. The LTM8028MP is 40 µVRMS guaranteed to meet specifications over the full –55°C to 125°C 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: Guaranteed by design, characterization and correlation with statistical process controls. Note 4: Unless otherwise stated, the absolute minimum voltage is zero. 8028f For more information www.linear.com/LTM8028 3 LTM8028 TYPICAL PERFORMANCE CHARACTERISTICS Power Loss vs Output Current, 1VOUT 3 2 36VIN 24VIN 12VIN 6VIN 1 0 0 1 3 4 2 OUTPUT CURRENT (A) 5 5 4 4 POWER LOSS (W) POWER LOSS (W) POWER LOSS (W) 4 3 2 36VIN 24VIN 12VIN 6VIN 1 0 5 0 1 3 4 2 OUTPUT CURRENT (A) 8028 G01 2 36VIN 24VIN 12VIN 6VIN 1 3 4 2 OUTPUT CURRENT (A) 2 0 5 36VIN 24VIN 12VIN 6VIN 0 1 3 4 2 OUTPUT CURRENT (A) 1400 800 600 400 200 1 2 4 3 OUTPUT CURRENT (A) 600 400 0 5 5 8028 G07 0 1 2 3 8026 G06 Input Current vs Output Current, 1.5VOUT 2000 1600 1000 800 600 1400 1200 1000 800 600 400 400 200 200 0 1 3 2 OUTPUT CURRENT (A) 6VIN 12VIN 24VIN 36VIN 1800 1200 0 5 4 OUTPUT CURRENT (A) 6VIN 12VIN 24VIN 36VIN 1600 1000 0 800 200 INPUT CURRENT (mA) 1200 1000 Input Current vs Output Current, 1.2VOUT 1800 5 6VIN 12VIN 24VIN 36VIN 8028 G05 INPUT CURRENT (mA) INPUT CURRENT (mA) 1400 3 4 2 OUTPUT CURRENT (A) 8028 G03 1200 1 6VIN 12VIN 24VIN 36VIN 1 Input Current vs Output Current, 0.8VOUT 3 Input Current vs Output Current, 1VOUT 1600 0 1400 8028 G04 0 0 5 4 POWER LOSS (W) POWER LOSS (W) 4 3 36VIN 24VIN 12VIN 6VIN 1 5 0 2 Power Loss vs Output Current, 1.8VOUT 5 1 3 8028 G02 Power Loss vs Output Current, 1.5VOUT 0 Power Loss vs Output Current, 1.2VOUT INPUT CURRENT (mA) 5 Power Loss vs Output Current, 0.8VOUT 5 4 8028 G08 0 0 1 3 4 2 OUTPUT CURRENT (A) 5 8028 G09 8028f 4 For more information www.linear.com/LTM8028 LTM8028 TYPICAL PERFORMANCE CHARACTERISTICS 6.0 1000 1000 500 5.8 OUTPUT CURRENT (A) 1500 0 Output Current vs Input Voltage, Output Shorted 1200 6VIN 12VIN 24VIN 36VIN 2000 INPUT CURRENT (mA) Input Current vs Input Voltage, Output Shorted INPUT CURRENT (mA) 2500 Input Current vs Output Current, 1.8VOUT 800 600 400 1 3 4 2 OUTPUT CURRENT (A) 5 0 0 10 20 30 INPUT VOLTAGE (V) 8028 G10 10µs/DIV COUT = 100µF + 22µF + 10µF + 4.7µF 5.0 40 0 12 18 24 INPUT VOLTAGE (V) 30 Transient Response, Demo Board, 1.5V VOUT 20mV/DIV VOUT 20mV/DIV IOUT 2A/DIV ∆IOUT 0.5A TO 5A 1µs RISE/FALL TIME IOUT 2A/DIV ∆IOUT 0.5A TO 5A 1µs RISE/FALL TIME Transient Response, Demo Board, 1.8V 10µs/DIV COUT = 100µF + 22µF + 10µF + 4.7µF 36 8028 G12 Transient Response, Demo Board, 1.2V 8028 G13 6 8038 G11 Transient Response, Demo Board, 1V VOUT 20mV/DIV IOUT 2A/DIV ∆IOUT 0.5A TO 5A 1µs RISE/FALL TIME 5.4 5.2 200 0 5.6 8028 G14 10µs/DIV COUT = 100µF + 22µF + 10µF + 4.7µF 8028 G15 Output Current vs IMAX Voltage, 12VIN Output Noise, 1.8VOUT 6 VOUT 20mV/DIV 500µV/DIV 20µs/DIV COUT = 100µF + 22µF + 10µF + 4.7µF 8028 G16 1µs/DIV MEASURED WITH HP461A AMPLIFIER (150MHz BW) AT J5 BNC CONNECTOR ON DC1738 DEMO BOARD fSW = 500kHz COUT = 137µF 5A LOAD 8028 G17 OUTPUT CURRENT (A) IOUT 2A/DIV ∆IOUT 0.5A TO 5A 1µs RISE/FALL TIME 5 4 3 2 1 0 0 0.5 1.0 1.5 IMAX VOLTAGE (V) 2.0 8028 G18 8028f For more information www.linear.com/LTM8028 5 LTM8028 TYPICAL PERFORMANCE CHARACTERISTICS Temperature Rise vs Output Current, 0.8VOUT TEMPERATURE RISE (°C) 5 0 –5 60 50 50 40 30 20 36VIN 24VIN 12VIN 6VIN 10 –10 –15 60 0.3 0.6 0.9 MARGA VOLTAGE (V) 0 0 1.2 0 1 8028 G19 20 60 50 50 50 TEMPERATURE RISE (°C) 60 20 36VIN 24VIN 12VIN 6VIN 10 0 0 1 2 3 4 OUTPUT CURRENT (A) 40 30 20 36VIN 24VIN 12VIN 6VIN 10 5 0 0 1 40 30 20 36VIN 24VIN 12VIN 6VIN 0 0 1 2 3 4 OUTPUT CURRENT (A) 8028 G23 Output Noise Spectral Density 5 2 3 4 OUTPUT CURRENT (A) 10 5 2 3 4 OUTPUT CURRENT (A) 8028 G22 5 8028 G24 Soft-Start Waveform vs CSS 10 CSS = OPEN 1 CSS = 10nF CSS = 100nF 500mV/DIV µV/√Hz 1 Temperature Rise vs Output Current, 1.8VOUT 60 30 0 8028 G21 Temperature Rise vs Output Current, 1.5VOUT 40 36VIN 24VIN 12VIN 6VIN 8028 G20 Temperature Rise vs Output Current, 1.2VOUT TEMPERATURE RISE (°C) 30 0 5 2 3 4 OUTPUT CURRENT (A) 40 10 TEMPERATURE RISE (°C) VOUT CHANGE (%) 10 Temperature Rise vs Output Current, 1VOUT TEMPERATURE RISE (°C) 15 Output Voltage Change vs MARGA Voltage, 1VOUT CSS = 47nF 0.1 0.01 0.001 2ms/DIV VIN = 12V 5A RESISTIVE LOAD COUT = 4.7µF + 10µF + 22µF CBKV = 100µF + 470µF COUT = 137µF VOUT = 1.8V IOUT = 5A VIN = 12V 10 100 1k 10k FREQUENCY (Hz) 100k 8028 G26 1M 8028 G25 8028f 6 For more information www.linear.com/LTM8028 LTM8028 PIN FUNCTIONS VOUT (Bank 1): Power Output Pins. Apply the output filter capacitor and the output load between these and the GND pins. BKV (Bank 2): Buck Regulator Output. Apply the step-down regulator’s bulk capacitance here (refer to Table 1). Do not connect this to the load. Do not drive a voltage into BKV. GND (Bank 3): Tie these GND pins to a local ground plane below the LTM8028 and the circuit components. In most applications, the bulk of the heat flow out of the LTM8028 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. VIN (Bank 4): The VIN pin supplies current to the LTM8028’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. VO0, VO1, VO2 (Pin A6, Pin B6, Pin A5): Output Voltage Select. These three-state pins combine to select a nominal output voltage from 0.8V to 1.8V in increments of 50mV. See Table 2 in the Applications Information section that defines the VO2, VO1 and VO0 settings versus VOUT. MARGA (Pin A7): Analog Margining: This pin margins the output voltage over a continuous analog range of ±10%. Tying this pin to GND adjusts output voltage by –10%. Driving this pin to 1.2V adjusts output voltage by 10%. A voltage source or a voltage output DAC is ideal for driving this pin. If the MARGA function is not used, either float this pin or terminate with a 1nF capacitor to GND. TEST (Pin A8): Factory Test. Leave this pin open. SENSEP (Pin A9): Kelvin Sense for VOUT. The SENSEP pin is the inverting input to the error amplifier. Optimum regulation is obtained when the SENSEP pin is connected to the VOUT pins of the regulator. In critical applications, the resistance of PCB traces between the regulator and the load can cause small voltage drops, creating a load regulation error at the point of load. Connecting the SENSEP pin at the load instead of directly to VOUT eliminates this voltage error. The SENSEP pin input bias current depends on the selected output voltage. SENSEP pin input current varies from 50μA typically at VOUT = 0.8V to 300μA typically at VOUT = 1.8V. SENSEP must be connected to VOUT, either locally or remotely. VOB (Pin B5): Bias for VO0, VO1, VO2. This is a 3.3V source to conveniently pull up the VO0, VO1, VO2 pins, if desired. If not used, leave this pin floating. IMAX (Pin D1): Sets the Maximum Output Current. Connect a resistor/ NTC thermistor network to the IMAX pin to reduce the maximum regulated output current of the LTM8028 in response to temperature. This pin is internally pulled up to 2V through a 10k resistor, and the control voltage range is 0V to 1.5V. SS (Pin D2): The Soft-Start Pin. Place an external capacitor to ground to limit the regulated current during start-up conditions. The soft-start pin has an 11μA charging current. RT (Pin E1): The RT pin is used to program the switching frequency of the LTM8028’s buck regulator by connecting a resistor from this pin to ground. The Applications Information section of the data sheet includes a table to determine the resistance value based on the desired switching frequency. When using the SYNC function, set the frequency to be 20% lower than the SYNC pulse frequency. Do not leave this pin open. SYNC (Pin E2): Frequency Synchronization Pin. This pin allows the switching frequency to be synchronized to an external clock. The RT resistor should be chosen to operate the internal clock at 20% slower than the SYNC pulse frequency. This pin should be grounded when not in use. Do not leave this pin floating. When laying out the board, avoid noise coupling to or from the SYNC trace. See the Synchronization section in Applications Information. RUN (Pin F1): The RUN pin acts as an enable pin and turns off the internal circuitry at 1.55V. The pin does not have any pull-up or pull-down, requiring a voltage bias for normal part operation. The RUN pin is internally clamped, so it may be pulled up to a voltage source that is higher than the absolute maximum voltage of 6V, provided the pin current does not exceed 100μA. 8028f For more information www.linear.com/LTM8028 7 LTM8028 BLOCK DIAGRAM 2.2µH VIN 0.2µF BKV VOUT 10Ω SENSEP 10µF 5A LINEAR REGULATOR TEST MARGA PGOOD RUN SYNC IMAX INPUT-OUTPUT CONTROL CURRENT MODE CONTROLLER SS RT VIN INTERNAL POWER VOB GND VO2 VO1 VO0 8028 BD 8028f 8 For more information www.linear.com/LTM8028 LTM8028 OPERATION Current generation FPGA and ASIC processors place stringent demands on the power supplies that power the core, I/O and transceiver channels. Power supplies that power these processors have demanding output voltage specifications, especially at low voltages, where they require tight tolerances, small transient response excursions, low noise and high bandwidth to achieve the lowest bit-error rates. This can be accomplished with some high performance linear regulators, but this can be inefficient for high current and step-down ratios. The LTM8028 is a 5A high efficiency, UltraFast transient response linear regulator. It integrates a buck regulator with a high performance linear regulator, providing a precisely regulated output voltage digitally programmable from 0.8V to 1.8V. As shown in the Block Diagram, the LTM8028 contains a current mode controller, power switches, power inductor, linear regulator, and a modest amount of capacitance. To achieve high efficiency, the integrated buck regulator is automatically controlled (Input-Output Control on the Block Diagram) to produce the optimal voltage headroom to balance efficiency, tight regulation and transient response at the linear regulator output. Figure 1 is a composite graph of the LTM8028’s power loss compared to the theoretical power loss of a traditional linear regulator. Note that the power loss (left hand Y axis) is plotted on the log scale. For 1.2VOUT at 5A and 24VIN 60 1000 55 50 100 45 TEMPERATURE RISE 10 40 POWER LOSS TEMPERATURE RISE (°C) POWER LOSS (W) TRADITIONAL LINEAR REGULATOR POWER LOSS 35 0 0 10 20 30 INPUT VOLTAGE (V) 40 30 8028 F01 Figure 1. This Graph Shows the Full Load Power Loss and Temperature Rise of the LTM8028 over a Range of Input Voltages. Compare These Numbers to a Traditional Linear Regulator Powering the Same Load an Operating Condition. Note the Log Scale for Power Loss. the LTM8028 only loses 4W, while the traditional linear regulator theoretically dissipates over 110W. The LTM8028 switching buck converter utilizes fixedfrequency, forced continuous current mode control to regulate its output voltage. This means that the switching regulator will stay in fixed frequency operation even as the LTM8028 output current falls to zero. The LTM8028 has an analog control pin, IMAX, to set the maximum allowable current output of the LTM8028. The analog control range of IMAX is from 0V to 1.5V. The RUN pin functions as a precision shutdown pin. When the voltage at the RUN pin is lower than 1.55V, switching is terminated. Below this threshold, the RUN pin sinks 5.5µA. This current can be used with a resistor between RUN and VIN to set the hysteresis. During start-up, the SS pin is held low until the part is enabled, after which the capacitor at the soft-start pin is charged with an 11μA current source. The switching frequency is determined by a resistor at the RT pin. The LTM8028 may also be synchronized to an external clock through the use of the SYNC pin. The output linear regulator supplies up to 5A of output current with a typical dropout voltage of 85mV. Its high bandwidth provides UltraFast transient response using low ESR ceramic output capacitors, saving bulk capacitance, PCB area and cost. The output voltage for the LTM8028 is digitally selectable in 50mV increments over a 0.8V to 1.8V range, and analog margining function allows the user to adjust system output voltage over a continuous ±10% range. It also features a remote sense pin for accurate regulation at the load, and a PGOOD circuit that indicates whether the output is in or out of regulation or if an internal fault has occurred. The LTM8028 is equipped with a thermal shutdown to protect the device during momentary overload conditions. It is set above the 125°C absolute maximum internal temperature rating to avoid interfering with normal specified operation, so internal device temperatures will exceed the absolute maximum rating when the overtemperature protection is active. So, continuous or repeated activation of the thermal shutdown may impair device reliability. During thermal shutdown, all switching is terminated and the SS pin is driven low. 8028f For more information www.linear.com/LTM8028 9 LTM8028 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 10μF to VIN and the recommended RT value (RT(OPTIMAL) in Table 1). Lower RT values (resulting in a higher operating frequency) may be used to reduce the output ripple. Do not use values below RT(MIN). 3. Apply a parallel combination of a 100μF ceramic and a 470μF electrolytic to BKV. The Sanyo OS-CON 6SEPC470M or United Chemi-Con APXF6R3ARA471MH80G work well for the electrolytic capacitor, but other devices with an ESR about 10mΩ may be used. 4. Apply a minimum of 37μF to VOUT. As shown in Table 1, this is usually a parallel combination of 4.7μF, 10μF and 22μF capacitors. 5. Apply an additional 100µF capacitor to VOUT if very small (2%) transient response is required. 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 LTM8028 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. Programming Output Voltage Three tri-level input pins, VO2, VO1 and VO0, select the value of output voltage. Table 2 illustrates the 3-bit digital wordto-output voltage resulting from setting these pins high, low or allowing them to float. These pins may be tied high or low by either pin-strapping them to VOB or driving them Table 1: Recommended Component Values and Configuration (TA = 25°C) VIN 6V to 36V 6V to 36V 6V to 36V 6V to 36V 6V to 36V 9V to 15V 9V to 15V 9V to 15V 9V to 15V 9V to 15V 18V to 36V 18V to 36V 18V to 36V 18V to 36V 18V to 36V VOUT 0.8V 1.0V 1.2V 1.5V 1.8V 0.8V 1.0V 1.2V 1.5V 1.8V 0.8V 1.0V 1.2V 1.5V 1.8V CIN: CBKV: COUT: COUT (Optional): Note: An input bulk capacitor is required. 10 fOPTIMAL RT(OPTIMAL) 200kHz 200k 250kHz 165k 250kHz 165k 250kHz 165k 315kHz 133k 250kHz 165k 280kHz 150k 300kHz 143k 315kHz 133k 350kHz 118k 200kHz 200k 250kHz 165k 250kHz 165k 250kHz 165k 315kHz 133k 10µF, 50V, 1210 100µF, 6.3V, 1210 + 470µF, 6.3V Low ESR Electrolytic 4.7µF, 4V, 0603 + 10µF, 10V, 0805 + 22µF, 10V, 0805 100µF, 6.3V, 1210 fMAX 250kHz 280kHz 315kHz 333kHz 385kHz 650kHz 750kHz 800kHz 1MHz 1MHz 250kHz 280kHz 315kHz 333kHz 385kHz RT(MIN) 165k 150k 133k 127k 107k 61.9k 53.6k 49.9k 40.2k 40.2k 165k 150k 133k 127k 107k 8028f For more information www.linear.com/LTM8028 LTM8028 APPLICATIONS INFORMATION with digital ports. Pins that float may either actually float or require logic that has Hi-Z output capability. This allows the output voltage to be dynamically changed if necessary. The output voltage is selectable from a minimum of 0.8V to a maximum of 1.8V in increments of 50mV. Table 2. VO2 to VO0 Setting vs Output Voltage VO2 VO1 VO0 VOUT(NOM) VO2 VO1 VO0 VOUT(NOM) 0 0 0 0.80V Z 0 1 1.35V 0 0 Z 0.85V Z Z 0 1.40V 0 0 1 0.90V Z Z Z 1.45V 0 Z 0 0.95V Z Z 1 1.50V 0 Z Z 1.00V Z 1 0 1.55V 0 Z 1 1.05V Z 1 Z 1.60V 0 1 0 1.10V Z 1 1 1.65V 0 1 Z 1.15V 1 X 0 1.70V 0 1 1 1.20V 1 X Z 1.75V Z 0 0 1.25V 1 X 1 1.80V Z 0 Z 1.30V The output capacitance for BKV given in Table 1 specifies an electrolytic capacitor. Ceramic capacitors may also be used in the application, but it may be necessary to use more of them. Many high value ceramic capacitors have a large voltage coefficient, so the actual capacitance of the component at the desired operating voltage may be only a fraction of the specified value. Also, the very low ESR of ceramic capacitors may necessitate an additional capacitor for acceptable stability margin. A final precaution regarding ceramic capacitors concerns the maximum input voltage rating of the LTM8028. A ceramic input capacitor combined with trace or cable inductance forms a high Q (under damped) tank circuit. If the LTM8028 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. Why Do Multiple, Small Value Output Capacitors Connected in Parallel Work Better? X = Don’t Care, 0 = Low, Z = Float, 1 = High Capacitor Selection Considerations The CIN, CBKV 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. 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. The parasitic series inductance (ESL) and resistance (ESR) of a capacitor can have a detrimental impact on the transient and ripple/noise response of a linear regulator. Employing a number of capacitors in parallel will reduce this parasitic impedance and improve the performance of the linear regulator. In addition, PCB vias can add significant inductance, so the fundamental decoupling capacitors must be mounted on the same copper plane as the LTM8028. The most area efficient parallel capacitor combination is a graduated 4/2/1 scale capacitances of the same case size, such as the 37μF combination in Table 1, made up of 22μF, 10μF and 4.7μF capacitors in parallel. Capacitors with small case sizes have larger ESR, while those with larger case sizes have larger ESL. As seen in Table 1, the optimum case size is 0805, followed by a larger, fourth bulk energy capacitor, case sized 1210. In general, the large fourth capacitor is required only if very tight transient response is required. 8028f For more information www.linear.com/LTM8028 11 LTM8028 APPLICATIONS INFORMATION Output Voltage Margining The LTM8028’s analog margining pin, MARGA, provides a continuous output voltage adjustment range of ±10%. It margins VOUT by adjusting the internal 600mV reference voltage up and down. Driving MARGA with 600mV to 1.2V provides 0% to 10% of adjustment. Driving MARGA with 600mV to 0V provides 0% to –10% of adjustment. If unused, allow MARGA to float or bypass this pin with a 1nF capacitor to GND. Note that the analog margining function does not adjust the PGOOD threshold. Therefore, negative analog margining may trip the PGOOD comparator and toggle the PGOOD flag. Power Good PGOOD pin is an open-drain NMOS digital output that actively pulls low if any one of these fault modes is detected: • VOUT is less than 90% of VOUT(NOMINAL) on the rising edge of VOUT. • VOUT drops below 85% of VOUT(NOMINAL) for more than 25μs. • Internal faults such as loss of internal housekeeping voltage regulation, reverse-current on the power switch and excessive temperature. SENSEP and Load Regulation The LTM8028 provides a Kelvin sense pin for VOUT, allowing the application to correct for parasitic package and PCB IR drops. If the load is far from the LTM8028, running a separate line from SENSEP to the remote load will correct for IR voltage drops and improve load regulation. SENSEP is the only voltage feedback that the LTM8028 uses to regulate the output, so it must be connected to VOUT, either locally or at the load. In some systems, a loss of feedback signal equates to a loss of output control, potentially damaging the load. If the SENSEP signal is inadvertently disconnected from the load, internal safety circuits in the LTM8028 prevent the output from running away. This also limits the amount of correction to about 0.2V. Bear in mind that the linear regulator of the LTM8028 is a high bandwidth power device. If the load is very far from the LTM8028, the parasitic impedance of the remote connection may interfere with the internal control loop and adversely affect stability. If SENSEP is connected to a remote load, the user must evaluate the load regulation and dynamic load response of the LTM8028. Short-Circuit and Overload Recovery Like many IC power regulators, the internal linear regulator has safe operating area (SOA) protection. The safe area protection decreases current limit as input-to-output voltage increases and keeps the power transistor inside a safe operating region for all values of input-to-output voltage up to the absolute maximum voltage rating. Under maximum ILOAD and maximum VIN-VOUT conditions, the internal linear regulator’s power dissipation peaks at about 1.5W. If ambient temperature is high enough, die junction temperature will exceed the 125°C maximum operating temperature. If this occurs, the LTM8028 relies on two additional thermal safety features. At about 145°C, the device is designed to make the PGOOD output pull low providing an early warning of an impending thermal shutdown condition. At 165°C typically, the LTM8028 is designed to engage its thermal shutdown and the output is turned off until the IC temperature falls below the thermal hysteresis limit. The SOA protection decreases current limit as the in-to-out voltage increases and keeps the power dissipation at safe levels for all values of inputto-output voltage. 8028f 12 For more information www.linear.com/LTM8028 LTM8028 APPLICATIONS INFORMATION Reverse Voltage Switching Frequency Synchronization The LTM8028 incorporates a circuit that detects if BKV decreases below VOUT. If this voltage condition is detected, internal circuitry turns off the drive to the internal linear regulator’s pass transistor, thereby turning off the output. This circuit’s intent is to limit and prevent back-feed current from VOUT to VIN if the input voltage collapses due to a fault or overload condition. Do not apply a voltage to BKV. The nominal switching frequency of the LTM8028 is determined by the resistor from the RT pin to GND and may be set from 200kHz to 1MHz. The internal oscillator may also be synchronized to an external clock through the SYNC pin. The external clock applied to the SYNC pin must have a logic low below 0.25V and a logic high greater than 1.25V. The input frequency must be 20% higher than the frequency determined by the resistor at the RT pin. The duty cycle of the input signal needs to be greater than 10% and less than 90%. Input signals outside of these specified parameters will cause erratic switching behavior and subharmonic oscillations. When synchronizing to an external clock, please be aware that there will be a fixed delay from the input clock edge to the edge of switch. The SYNC pin must be tied to GND if the synchronization to an external clock is not required. When SYNC is grounded, the switching frequency is determined by the resistor at the RT pin. Programming Switching Frequency The LTM8028 has an operational switching frequency range between 200kHz and 1MHz. This frequency is programmed with an external resistor from the RT pin to ground. Do not leave this pin open under any condition. The RT pin is also current limited to 60μA. See Table 3 for resistor values and the corresponding switching frequencies. Table 3. RT Resistor Values and Their Resultant Switching Frequencies SWITCHING FREQUENCY (MHz) 1 0.750 0.5 0.3 0.2 RT (kΩ) 40.2 53.6 82.5 143 200 Switching 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. A higher switching frequency, for example, will yield a smaller output ripple, while a lower frequency will reduce power loss. Switching too fast, however, can generate excessive heat and even possibly damage the LTM8028 in fault conditions. Switching too slow can result in a final design that has too much output capacitance or sub-harmonic oscillations that cause excessive ripple. In all cases, stay below the stated maximum frequency (fMAX) given in Table 1. Soft-Start The soft-start function controls the slew rate of the power supply output voltage during start-up. A controlled output voltage ramp minimizes output voltage overshoot, reduces inrush current from the VIN supply, and facilitates supply sequencing. A capacitor connected from the SS pin to GND programs the slew rate. The capacitor is charged from an internal 11μA current source to produce a ramped output voltage. Maximum Output Current Adjust To adjust the regulated load current, an analog voltage is applied to the IMAX pin. Varying the voltage between 0V and 1.5V adjusts the maximum current between the minimum and the maximum current, 5.6A typical. Above 1.5V, the control voltage has little effect on the regulated inductor current. A graph of the output current versus IMAX voltage is given in the Typical Performance Characteristics 8028f For more information www.linear.com/LTM8028 13 LTM8028 APPLICATIONS INFORMATION section. There is a 10k resistor internally connected from a 2V reference to the IMAX pin, so the current limit can be set as shown in Figure 2 with the following equation: RIMAX = 10 •IMAX kΩ 7.467 –IMAX LTM8028 IMAX LTM8028 when the RUN pin voltage falls to 1.55V. There is also an internal current source that provides 5.5μA of pull-down current to program additional UVLO hysteresis. For RUN rising, the current source is sinking 5.5µA until RUN = 1.68V, after which it turns off. For RUN falling, the current source is off until the RUN = 1.55V, after which it sinks 5.5µA. The following equations determine the voltage divider resistors for programming the falling UVLO voltage and rising enable voltage (VENA) as configured in Figure 3. 1.55 •R2 R1= UVLO – 1.55 RIMAX 8028 F02 Figure 2. Setting The Output Current Limit, IMAX Thermal Shutdown At about 145°C, the LTM8028 is designed to make the PGOOD output pull low providing an early warning of an impending thermal shutdown condition. At 165°C typically, the LTM8028 is designed to engage its thermal shutdown, discharge the soft-start capacitor and turn off the output until the internal temperature falls below the thermal hysteresis limit. When the part has cooled, the part automatically restarts. Note that this thermal shutdown is set to engage at temperatures above the 125°C absolute maximum internal operating rating to ensure that it does not interfere with functionality in the specified operating range. This means that internal temperatures will exceed the 125°C absolute maximum rating when the overtemperature protection is active, so repeated or prolonged operation under these conditions may impair the device’s reliability. UVLO and Shutdown The LTM8028 has an internal UVLO that terminates switching, resets all logic, and discharges the soft-start capacitor for input voltages below 4.2V. The LTM8028 also has a precision RUN function that enables switching when the voltage at the RUN pin rises to 1.68V and shuts down the R2 = VENA – 1.084 •UVLO 5.5µA VIN LTM8028 VIN R2 RUN R1 8028 F03 Figure 3. UVLO Configuration The RUN pin has an absolute maximum voltage of 6V. To accommodate the largest range of applications, there is an internal Zener diode that clamps this pin, so that it can be pulled up to a voltage higher than 6V through a resistor that limits the current to less than 100µA. For applications where the supply range is greater than 4:1, size R2 greater than 375k. PCB Layout Most of the headaches associated with PCB layout have been alleviated or even eliminated by the high level of integration of the LTM8028. The LTM8028 is nevertheless a switching power supply, and care must be taken to 8028f 14 For more information www.linear.com/LTM8028 LTM8028 APPLICATIONS INFORMATION 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 4 for a suggested layout. Ensure that the grounding and heat sinking are acceptable. A few rules to keep in mind are: 1. Place the RT resistor as close as possible to its respective pins. 2. Place the CIN capacitor as close as possible to the VIN and GND connection of the LTM8028. 3. Place the COUT capacitors as close as possible to the VOUT and GND connection of the LTM8028. 4. Place the CIN, CBKV and COUT capacitors such that their ground current flow directly adjacent or underneath the LTM8028. 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 LTM8028. 6. 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 4. The LTM8028 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 might use very small via holes. It should employ more thermal vias than a board that uses larger holes. GND COUT CBKV BKV VOUT SENSEP TEST MARGA PGOOD VO0 (OUTPUT IS VO1 SET TO 1.55V) VO2 VOB GND SS SYNC IMAX RT RUN GND THERMAL VIAS VIN CIN 8028 F04 Figure 4. Layout Showing Suggested External Components, GND Plane and Thermal Vias 8028f For more information www.linear.com/LTM8028 15 LTM8028 APPLICATIONS INFORMATION Load Sharing Hot-Plugging Safely Each LTM8028 features an accurate current limit that enables the use of multiple devices to power a load heavier than 5A. This is accomplished by simply tying the VOUT terminals of the LTM8028s together, and set the outputs of the parallel units to the same voltage. There is no need to power the μModule regulators from the same power supply. That is, the application can use multiple LTM8028s, each powered from separate input voltage rails and contribute a different amount of current to the load as dictated by the programmed current limit. Keep in mind that the paralleled LTM8028s will not share current equally. In most cases, one LTM8028 will provide almost all the load until its current limit is reached, and then the other unit or units will start to provide current. This might be an unacceptable operating condition in other power regulators, but the accurate current loop of the LTM8028 controls the electrical and thermal performance of each individual μModule regulator. This prevents the oscillations, thermal runaway and other issues that other regulators might suffer. An example of two LTM8028s connected in parallel to deliver 1.8V at 10A, while powered from two disparate power sources, is given in the Typical Applications section. A graph of the output current delivered from each μModule regulator is given below in Figure 5. The small size, robustness and low impedance of ceramic capacitors make them an attractive option for the input bypass capacitor of LTM8028. However, these capacitors can cause problems if the LTM8028 is plugged into a live input supply (see 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 LTM8028 can ring to more than twice the nominal input voltage, possibly exceeding the LTM8028’s rating and damaging the part. If the input supply is poorly controlled or the user will be plugging the LTM8028 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 physically large. CURRENT DELIVERED BY LTM8028s (A) 6 5 4 3 2 1 0 1 2 4 6 8 TOTAL LOAD CURRENT (A) 10 8028 F05 Figure 5. In Most Cases Where Paralleled LTM8028s are Used, One µModule Will Deliver All of The Load Current Until Its Current Limit Is Reached, Then The Other Unit(s) Will Provide Current. The Tightly Controlled Output Current Prevents Oscillations and Thermal Runaway Observed In Other Types of Regulators 8028f 16 For more information www.linear.com/LTM8028 LTM8028 APPLICATIONS INFORMATION Thermal Considerations The LTM8028 relies on two thermal safety features. At about 145°C, the device is designed to pull the PGOOD output low providing an early warning of an impending thermal shutdown condition. At 165°C typically, the LTM8028 is designed to engage its thermal shutdown and the output is turned off until the IC temperature falls below the thermal hysteresis limit. Note that these temperature thresholds are above the 125°C absolute maximum rating 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. The LTM8028 output current may need to be derated if it is required to operate in a high ambient temperature. 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 the LTM8028 mounted to a 58cm2 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. For increased accuracy and fidelity to the actual application, many designers use finite element analysis (FEA) to predict thermal performance. To that end, the Pin Configuration of the data sheet typically gives four thermal coefficients: θJA – Thermal resistance from junction to ambient θJCbottom – Thermal resistance from junction to the bottom of the product case θJCtop – Thermal resistance from junction to top of the product case 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: θJA 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 “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. θJCbottom is the junction-to-board thermal resistance with all of the component power dissipation flowing through the bottom of the package. In the typical µModule regulator, 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. θJCtop is determined with nearly all of the component power dissipation flowing through the top of the package. As the electrical connections of the typical µModule regulator 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 θJCbottom, this value may be useful for comparing packages but the test conditions don’t generally match the user’s application. θJB is the junction-to-board thermal resistance where almost all of the heat flows through the bottom of the µModule regulator and into the board, and is really the sum of the θJCbottom 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 2-sided, 2-layer board. This board is described in JESD 51-9. θJBoard – Thermal resistance from junction to the printed circuit board. 8028f For more information www.linear.com/LTM8028 17 LTM8028 APPLICATIONS INFORMATION Given these definitions, it should now be apparent that none of these thermal coefficients reflects an actual physical operating condition of a µModule regulator. 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 is given in Figure 6: The blue resistances are contained within the µModule regulator, and the green are outside. The die temperature of the LTM8028 must be lower than the maximum rating of 125°C, so care should be taken in the layout of the circuit to ensure good heat sinking of the LTM8028. The bulk of the heat flow out of the LTM8028 is through the bottom of the module 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 AMBIENT BOARD-TO-AMBIENT RESISTANCE 8028 F06 µMODULE DEVICE Figure 6. Thermal Model of µModule 8028f 18 For more information www.linear.com/LTM8028 LTM8028 TYPICAL APPLICATIONS Transient Response from 0.5A to 5A, 1µs Load Current Rise and Fall Time, 12VIN 1V at 5A Regulator with 2% Transient Response VIN 6V TO 36V LTM8028 VIN 402k 10µF 0.01µF RUN MARGA IMAX BKV SS 165k RT VOUT 1V 5A VOUT LINEAR REGULATOR SENSEP PGOOD SYNC GND VOB VO0 VO1 VO2 137µF* + 100µF LOAD CURRENT 2A/DIV VOUT 20mV/DIV 470µF 8028 TA03 1µs/DIV 8028 TA02 *137µF = 4.7µF + 10µF + 22µF +100µF IN PARALLEL Output Voltage vs Current 1.8V Regulator with 3.5A Current Limit 2.0 1.8 10µF 402k 10k RUN MARGA LINEAR REGULATOR SENSEP BKV IMAX SS 0.01µF 133k RT VOUT 1.8V 3.5A VOUT PGOOD SYNC GND VOB VO0 VO1 VO2 37µF* + 100µF 1.6 OUTPUT VOLTAGE (V) VIN 6V TO 36V LTM8028 VIN 1.4 1.2 1.0 0.8 0.6 0.4 470µF 8028 TA04 0.2 0 *37µF = 4.7µF + 10µF + 22µF IN PARALLEL 0 2 1 3 OUTPUT CURRENT (A) 4 8028 TA05 8028f For more information www.linear.com/LTM8028 19 LTM8028 TYPICAL APPLICATIONS 1.8V, 10A with Two LTM8028s Powered from Two Different Sources Each µModule Regulator Is Limited to Provide a Maximum of 5A VIN 24V 10µF LTM8028 VIN 402k 20.5k RUN MARGA BKV IMAX SS 0.01µF 133k VIN 12V 10µF RT PGOOD SYNC 20.5k GND LTM8028 VIN 150k RUN MARGA VOB VO0 VO1 VO2 + 100µF 330µF BKV IMAX RT 17µF* VOUT LINEAR REGULATOR SENSEP SS 0.01µF 133k VOUT 1.8V 10A VOUT LINEAR REGULATOR SENSEP PGOOD SYNC GND VOB VO0 VO1 VO2 17µF* + 100µF 330µF 8028 TA06 *17µF = 2.2µF + 4.7µF + 10µF IN PARALLEL 8028f 20 For more information www.linear.com/LTM8028 LTM8028 TYPICAL APPLICATIONS Low Noise LTM8028 Powering 16-Bit, 125Msps ADC LTM8028 VIN 402k 10µF 0.01µF RUN MARGA IMAX SS 133k RT VOUT 1.8V 5A VOUT LINEAR REGULATOR SENSEP BKV GND SYNC VOB VO0 VO1 VO2 VDD AIN+ PGOOD 137µF* + OVDD LTC®2185 ADC AIN– 100µF ENC+ ENC– GND 470µF 1.8V 0V 8028 TA08a *137µF = 4.7µF + 10µF + 22µF + 100µF IN PARALLEL 32k-Point FFT, fIN = 70.3MHz, –1dBFS, 100Msps 0 –10 –20 –30 MAGNITUDE (dBFS) VIN 6V TO 36V –40 –50 –60 –70 –80 –90 –100 –110 –120 0 10 30 20 FREQUENCY (MHz) 40 50 8028 TA08b 8028f For more information www.linear.com/LTM8028 21 LTM8028 PACKAGE DESCRIPTION Table 3. Pin Assignment Table (Arranged by Pin Number) PIN A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 NAME GND GND GND GND VO2 VO0 MARGA TEST SENSEP VOUT VOUT PIN B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 NAME GND GND GND GND VOB VO1 PGOOD GND GND VOUT VOUT PIN C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 NAME GND GND GND GND GND GND GND GND GND VOUT VOUT PIN D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 NAME IMAX SS GND GND GND GND GND GND GND VOUT VOUT PIN E1 E2 E3 E4 E5 E6 E7 E8 E9 E10 E11 NAME RT SYNC GND GND GND GND GND GND GND VOUT VOUT PIN G1 G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 NAME – – – GND GND GND GND GND GND GND GND PIN H1 H2 H3 H4 H5 H6 H7 H8 H9 H10 H11 NAME VIN VIN – GND GND GND GND GND GND GND GND PIN J1 J2 J3 J4 J5 J6 J7 J8 J9 J10 J11 NAME VIN VIN – GND GND GND GND GND BKV BKV BKV PIN K1 K2 K3 K4 K5 K6 K7 K8 K9 K10 K11 NAM VIN VIN – GND GND GND GND GND BKV BKV BKV PIN L1 L2 L3 L4 L5 L6 L7 L8 L9 L10 L11 NAME VIN VIN – GND GND GND GND GND BKV BKV BKV PIN F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 D11 NAME RUN GND GND GND GND GND GND GND GND VOUT VOUT PACKAGE PHOTO 8028f 22 For more information www.linear.com/LTM8028 aaa Z 0.630 ±0.025 Ø 114x E 2.540 SUGGESTED PCB LAYOUT TOP VIEW 2.540 PACKAGE TOP VIEW 1.270 4 0.000 PAD “A1” CORNER 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/LTM8028 6.350 5.080 3.810 2.540 1.270 0.000 1.270 2.540 3.810 5.080 6.350 X D 3.95 – 4.05 aaa Z 6.350 5.080 3.810 3.810 5.080 6.350 SYMBOL A A1 A2 b b1 D E e F G aaa bbb ccc ddd eee NOM 4.92 0.60 4.32 0.75 0.63 15.0 15.0 1.27 12.70 12.70 DIMENSIONS 0.15 0.10 0.20 0.30 0.15 MAX 5.12 0.70 4.42 0.90 0.66 NOTES DETAIL B PACKAGE SIDE VIEW TOTAL NUMBER OF BALLS: 114 MIN 4.72 0.50 4.22 0.60 0.60 DETAIL A b1 0.27 – 0.37 SUBSTRATE A1 ddd M Z X Y eee M Z DETAIL B MOLD CAP ccc Z A2 A Z (Reference LTC DWG # 05-08-1894 Rev A) Øb (114 PLACES) // bbb Z BGA Package 114-Lead (15mm × 15mm × 4.92mm) F e b b 10 9 7 G 6 5 e 4 PACKAGE BOTTOM VIEW 8 3 2 1 DETAILS OF PAD #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE PAD #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE 4 TRAY PIN 1 BEVEL COMPONENT PIN “A1” 7 ! PACKAGE IN TRAY LOADING ORIENTATION LTMXXXXXX µModule PAD 1 BGA 114 1112 REV A 3 7 SEE NOTES SEE NOTES L K J H G F E D C B A PACKAGE ROW AND COLUMN LABELING MAY VARY AMONG µModule PRODUCTS. REVIEW EACH PACKAGE LAYOUT CAREFULLY 6. THE TOTAL NUMBER OF PADS: 114 5. PRIMARY DATUM -Z- IS SEATING PLANE LAND DESIGNATION PER JESD MO-222, SPP-010 3 2. ALL DIMENSIONS ARE IN MILLIMETERS NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994 11 DETAIL A LTM8028 PACKAGE DESCRIPTION Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. 8028f 23 LTM8028 TYPICAL APPLICATION 1V at 5A Regulator VIN 6V TO 36V LTM8028 VIN 402k 10µF 0.01µF RUN MARGA IMAX BKV SS 165k RT VOUT 1V 5A VOUT LINEAR REGULATOR SENSEP PGOOD SYNC GND VOB VO0 VO1 VO2 37µF* + 100µF 470µF 8028 TA07 *37µF = 4.7µF + 10µF + 22µF IN PARALLEL RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTM8032 Step-Down µModule Regulator, EN55022B Compliant 3.6V ≤ VIN ≤ 36V, 0.8V ≤ VOUT ≤ 10V, 2A LTM4613 Step-Down µModule Regulator, EN55022B Compliant 5V ≤ VIN ≤ 36V, 3.3V ≤ VOUT ≤ 15V, 8A LTM8027 60V, 4A Step-Down µModule Regulator 4.5V ≤ VIN ≤ 60V, 2.5V ≤ VOUT ≤ 24V, 4A LTM8048 Isolated µModule Converter 725V Isolation, 3.1V ≤ VIN ≤ 32V, 1.2V ≤ VOUT ≤ 12V, 300mA LTM4615 Triple Output Step-Down µModule Regulator 2.375V ≤ VIN ≤ 5.5V, 0.8V ≤ VOUT ≤ 5.5V, 4A, 4A, 1.5A LTM4620 Dual 13A, Single 26A Step-Down µModule Regulator 4.5V ≤ VIN ≤ 16V, 0.6V ≤ VOUT ≤ 2.5V, Up to 100A Current Sharing 8028f 24 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LTM8028 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LTM8028 LT 0413 • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 2013