LTM8046 3.1VIN to 31VIN, 2kVAC Isolated DC/DC µModule Converter Features Description 2kVAC Isolated µModule Converter (Tested to 3kVDC) n UL 60950 Recognized , File E464570 n Wide Input Voltage Range: 3.1V to 31V n5V at 550mA from 24V IN n1.8V to 12V Output Voltage n Current Mode Control n Programmable Soft-Start n User Configurable Undervoltage Lockout n SnPb or RoHS Compliant Finish n9mm × 15mm × 4.92mm BGA Package The LTM®8046 is an isolated flyback DC/DC µModule® (micromodule) converter. The LTM8046 has an isolation rating of 2kVAC. Included in the package are the switching controller, power switches, transformer, and all support components. Operating over an input voltage range of 3.1V to 31V, the LTM8046 supports an output voltage range of 1.8V to 12V, set by one resistor. Only output, input, and bias capacitors are needed to finish the design. An optional capacitor can be used to set the soft-start period. n ® Applications Industrial Sensors Industrial Switches n Ground Loop Mitigation n n The LTM8046 is packaged in a 9mm × 15mm × 4.92mm over-molded ball grid array (BGA) package suitable for automated assembly by standard surface mount equipment. The LTM8046 is available with SnPb (BGA) or RoHS compliant terminal finish. L, LT, LTC, LTM, Linear Technology, the Linear logo and µModule are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical Application Maximum Output Current vs VIN 2kV Isolated Low Noise µModule Regulator VIN RUN BIAS 1µF 8.45k FB SS GND ISOLATION BARRIER 1µF VOUT 5V VOUT 100µF VOUT– 2kVAC ISOLATION 8046 TA01a MAXIMUM OUTPUT CURRENT (mA) LTM8046 VIN 4.3V TO 26V 700 600 500 400 300 200 100 0 5 10 15 VIN (V) 20 25 30 8046 TA01b 8046fb For more information www.linear.com/LTM8046 1 LTM8046 Absolute Maximum Ratings Pin Configuration (Note 1) TOP VIEW VIN, RUN....................................................................32V FB, SS..........................................................................5V VOUT Relative to VOUT–...............................................16V VIN + 2VOUT (Note 5)..................................................36V BIAS................................................................. VIN + 0.1V GND to VOUT– Isolation (Note 2)............................2kVAC Maximum Internal Temperature (Note 3)............... 125°C Peak Solder Reflow Body Temperature.................. 245°C A BANK 4 VOUT B C BANK 3 VOUT– D E F G H BANK 2 GND J BANK 1 VIN K L RUN BIAS SS 1 2 3 4 5 FB 6 7 BGA PACKAGE 51-LEAD (15mm × 9mm × 4.92mm) TJMAX = 125°C, θJA = 21.9°C/W, θJCbottom = 7.9°C/W, θJCtop = 17.9°C/W, θJB = 8.4°C/W WEIGHT = 1.5g, θ VALUES DETERMINED PER JEDEC 51-9, 51-12 Order Information PART NUMBER PAD OR BALL FINISH PART MARKING* DEVICE FINISH CODE PACKAGE TYPE MSL RATING TEMPERATURE RANGE (See Note 3) LTM8046EY#PBF SAC305 (RoHS) LTM8046Y e1 BGA 3 –40°C to 125°C LTM8046IY#PBF SAC305 (RoHS) LTM8046Y e1 BGA 3 –40°C to 125°C LTM8046IY SnPb (63/37) LTM8046Y e0 BGA 3 –40°C to 125°C LTM8046MPY#PBF SAC305 (RoHS) LTM8046Y e1 BGA 3 –55°C to 125°C LTM8046MPY SnPb (63/37) LTM8046Y e0 BGA 3 –55°C to 125°C 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 • Pb-free and Non-Pb-free Part Markings: www.linear.com/leadfree • LGA and BGA Package and Tray Drawings: www.linear.com/packaging 8046fb 2 For more information www.linear.com/LTM8046 LTM8046 Electrical Characteristics The l denotes the specifications which apply over the full internal operating temperature range, otherwise specifications are at TA = 25°C, RUN = 12V (Note 3). PARAMETER CONDITIONS Minimum Input DC Voltage BIAS = VIN, VRUN = 2V BIAS Open, VRUN = 2V l l MIN VOUT DC Voltage RFB = 14.7k RFB = 8.45k RFB = 3.83k l 4.75 TYP 2.5 5 12 MAX UNITS 3.1 4.3 V V 5.25 V V V 1 µA VIN Quiescent Current VRUN = 0V VOUT Line Regulation 6V ≤ VIN ≤ 31V, IOUT = 0.15A, VRUN = 2V 1 % VOUT Load Regulation 0.05A ≤ IOUT ≤ 0.4A, VRUN = 2V 1.5 % VOUT Ripple (RMS) IOUT = 0.1A, BW = 1MHz 20 mV Isolation Test Voltage (Note 2) Input Short Circuit Current VOUT Shorted 3000 RUN Pin Input Threshold VRUN Pin Rising RUN Pin Current VRUN = 1V VRUN = 1.3V VDC 30 1.18 SS Threshold 1.24 1.30 V 2.5 0.1 µA µA 0.7 V µA SS Sourcing Current SS = 0V –8 BIAS Current VIN = 12V, BIAS = 5V, IOUT = 100mA 10 Minimum BIAS Voltage (Note 4) IOUT = 100mA 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 LTM8046 isolation is tested at 3kVDC for one second. Note 3: The LTM8046E is guaranteed to meet performance specifications from 0°C to 125°C. Specifications over the –40°C to 125°C internal temperature range are assured by design, characterization and correlation with statistical process controls. LTM8046I is guaranteed to meet specifications over the full –40°C to 125°C internal operating temperature range. The LTM8046MP is 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. mA mA 3.1 V Note 4: This is the BIAS pin voltage at which the internal circuitry is powered through the BIAS pin and not the integrated regulator. See BIAS Pin Considerations for details. Note 5: VIN + 2VOUT is defined as the sum of the voltage between (VIN – GND) added to twice the voltage between (VOUT – VOUT–). 8046fb For more information www.linear.com/LTM8046 3 LTM8046 Typical Performance Characteristics 1.8VOUT Efficiency vs Output Current 5VIN 65 12VIN 24VIN 60 55 75 5VIN 5VIN 70 12VIN 65 24VIN 60 55 50 45 BIAS = 3.3V 70 EFFICIENCY (%) 70 EFFICIENCY (%) 75 BIAS = 3.3V 0 200 400 600 OUTPUT CURRENT (mA) 50 800 0 100 200 300 400 500 OUTPUT CURRENT (mA) 600 BIAS = 3.3V 12VIN 75 5VIN 24VIN EFFICIENCY (%) 70 60 50 700 65 60 BIAS = 3.3V 0 100 200 300 400 500 OUTPUT CURRENT (mA) 12VOUT Efficiency vs Output Current 80 12VIN 5VIN BIAS = 3.3V 75 70 20VIN 70 700 600 8046 G03 EFFICIENCY (%) 75 24VIN 8VOUT Efficiency vs Output Current 80 BIAS = 3.3V 65 8046 G02 5VOUT Efficiency vs Output Current 80 12VIN 55 8046 G01 EFFICIENCY (%) 3.3VOUT Efficiency vs Output Current EFFICIENCY (%) 75 2.5VOUT Efficiency vs Output Current 65 60 5VIN 65 60 12VIN 55 50 55 0 200 400 OUTPUT CURRENT (mA) 50 600 45 0 8046 G04 5VIN 12VIN 100 50 300 150 12VIN 100 24VIN 50 0 200 600 400 OUTPUT CURRENT (mA) 800 8046 G07 100 150 200 OUTPUT CURRENT (mA) 0 250 BIAS = 3.3V 250 5VIN 5VIN 200 12VIN 150 100 24VIN 50 24VIN 0 50 3.3VOUT Input Current vs Output Current BIAS = 3.3V 200 INPUT CURRENT (mA) INPUT CURRENT (mA) 250 150 0 8046 G06 2.5VOUT Input Current vs Output Current BIAS = 3.3V 200 40 500 8046 G05 1.8VOUT Input Current vs Output Current 250 100 300 400 200 OUTPUT CURRENT (mA) INPUT CURRENT (mA) 50 55 0 200 400 600 OUTPUT CURRENT (mA) 800 8046 G08 0 0 200 400 600 OUTPUT CURRENT (mA) 400 8046 G09 8046fb 4 For more information www.linear.com/LTM8046 LTM8046 Typical Performance Characteristics 350 400 BIAS = 3.3V 12VIN 200 150 24VIN 100 200 20VIN 150 100 0 800 0 100 200 300 400 OUTPUT CURRENT (mA) 14 5VIN 9 0 500 12VIN 8 24VIN 7 6 0 50 100 150 200 OUTPUT CURRENT (mA) 250 8046 12 3.3VOUT Bias Current vs Output Current 13 BIAS = 3.3V 11 12VIN 10 8 24VIN 6 BIAS = 3.3V 5VIN 12 5VIN 12 BIAS CURRENT (mA) 4 12VIN 10 9 24VIN 8 7 6 5 2 4 0 0 200 400 600 OUTPUT CURRENT (mA) 800 5 0 200 400 600 OUTPUT CURRENT (mA) 12 16 5VIN 12VIN BIAS CURRENT (mA) 24VIN 10 8 6 4 2 0 200 400 OUTPUT CURRENT (mA) 600 8046 G16 16 13 11 20VIN 10 9 13 5VIN 11 10 9 8 7 7 0 700 100 200 300 400 OUTPUT CURRENT (mA) 500 8046 G17 12VIN 12 8 6 600 14 12VIN 12 BIAS = 3.3V 15 5VIN 14 200 300 400 500 OUTPUT CURRENT (mA) 12VOUT Bias Current vs Output Current BIAS = 3.3V 15 100 8046 G15 8VOUT Bias Current vs Output Current 5VOUT Bias Current vs Output Current BIAS = 3.3V 0 8046 G14 8046 G13 14 4 800 BIAS CURRENT (mA) BIAS CURREBT (mA) 100 2.5VOUT Bias Current vs Output Current BIAS = 3.3V 10 BIAS CURRENT (mA) 150 8046 G11 1.8VOUT Bias Current vs Output Current 0 200 50 8046 G10 11 12VIN 250 BIAS CURRENT (mA) 200 400 OUTPUT CURRENT (mA) 5VIN 300 50 0 BIAS = 3.3V 350 12VIN 250 50 0 400 5VIN 300 INPUT CURRENT (mA) 250 12VOUT Input Current vs Output Current BIAS = 3.3V 350 5VIN 300 INPUT CURRENT (mA) 8VOUT Input Current vs Output Current INPUT CURRENT (mA) 5VOUT Input Current vs Output Current 6 0 50 100 150 200 OUTPUT CURRENT (mA) 250 8046 G18 8046fb For more information www.linear.com/LTM8046 5 LTM8046 Typical Performance Characteristics Maximum Output Current vs VIN Maximum Output Current vs VIN 600 700 600 500 400 1.8VOUT 2.5VOUT 3.3VOUT 300 10 20 VIN (V) 7 MINIMUM LOAD (mA) MINIMUM LOAD (mA) 5 4 3 2 8VOUT 10 20 VIN (V) TEMPERATURE RISE (°C) 20 200 5VOUT 8VOUT 12VOUT 100 0 3 9 12 15 VIN (V) 18 21 10 0 8 16 VIN (V) 24 32 8046 G21 Input Current vs VIN Output Shorted BIAS = 3.3V 80 60 40 20 0 4 8 12 VIN (V) 3.3VIN 5VIN 12VIN 24VIN 800 0 0 10 20 VIN (V) 8046 G23 20 10 200 400 600 OUTPUT CURRENT (mA) 1.8VOUT 2.5VOUT 3.3VOUT 100 8046 G22 5 10 120 BIAS = 3.3V 15 0 15 0 27 5 30 20 8046 G20 Temperature Rise vs Output Current 2.5VOUT 0 24 12VOUT Minimum Load vs VIN 15 0 6 25 5 20 5VOUT 0 300 25 BIAS = 3.3V 6 0 400 8046 G19 Minimum Load vs VIN 1 500 0 30 BIAS = 3.3V 30 INPUT CURRENT (mA) 0 BIAS = 3.3V TEMPERATURE RISE (°C) 200 Minimum Load vs VIN 35 MINIMUM LOAD (mA) BIAS = 3.3V MAXIMUM OUTPUT CURRENT (mA) MAXIMUM OUTPUT CURRENT (mA) 800 30 40 8046 G24 Temperature Rise vs Output Current 3.3VOUT 15 10 3.3VIN 5VIN 12VIN 24VIN 5 0 0 8046 G25 200 400 600 OUTPUT CURRENT (mA) 800 8046 G26 8046fb 6 For more information www.linear.com/LTM8046 LTM8046 Typical Performance Characteristics 10 3.3VIN 5VIN 12VIN 24VIN 0 0 100 200 300 400 500 OUTPUT CURRENT (mA) 600 700 TEMPERATURE RISE (°C) 15 5 20 15 TEMPERATURE RISE (°C) TEMPERATURE RISE (°C) 20 Temperature Rise vs Output Current 8VOUT Temperature Rise vs Output Current 5VOUT 10 5 0 3.3VIN 5VIN 12VIN 0 100 200 300 OUTPUT CURRENT (mA) 8046 G27 400 Temperature Rise vs Output Current 12VOUT 15 10 5 0 3.3VIN 5VIN 12VIN 0 100 200 OUTPUT CURRENT (mA) 8046 G29 8046 G28 Output Ripple 300 Step Input Start-Up Waveform NO CSS 1V/ DIV 50mV/ DIV CSS = 0.1µF CSS = 0.033µF 2µs/DIV 24VIN, 5VOUT 570mA LOAD DC1559A DEMO BOARD UNMODIFIED 150MHz BW 8046 G30 200µs/DIV 24VIN, 5VOUT 20Ω RESISTIVE LOAD 8046 G31 8046fb For more information www.linear.com/LTM8046 7 LTM8046 Pin Functions VIN (Bank 1): VIN supplies current to the LTM8046’s internal regulator and to the integrated power switch. These pins must be locally bypassed with an external, low ESR capacitor. GND (Bank 2): This is the primary side local ground of the LTM8046 primary. In most applications, the bulk of the heat flow out of the LTM8046 is through the GND and VOUT– 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. VOUT– VOUT– – (Bank 3): VOUT is the return for VOUT. VOUT and comprise the isolated output of the LTM8046. In most applications, the bulk of the heat flow out of the LTM8046 is through the GND and VOUT– 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. Apply an external capacitor between VOUT and VOUT–. VOUT (Bank 4): VOUT and VOUT– comprise the isolated output of the LTM8046 flyback stage. Apply an external capacitor between VOUT and VOUT–. Do not allow VOUT– to exceed VOUT. RUN (Pin L3): A resistive divider connected to VIN and this pin programs the minimum voltage at which the LTM8046 will operate. Below 1.24V, the LTM8046 does not deliver power to the secondary. Above 1.24V, power will be delivered to the secondary and 8µA will be fed into the SS pin. When RUN is less than 1.24V, the pin draws 2.5µA, allowing for a programmable hysteresis. Do not allow a negative voltage (relative to GND) on this pin. BIAS (Pin L4): This pin supplies the power necessary to operate the LTM8046. It must be locally bypassed with a low ESR capacitor of at least 1μF. Do not allow this pin voltage to rise above VIN. SS (Pin L5): Place a soft-start capacitor here to limit inrush current and the output voltage ramp rate. Do not allow a negative voltage (relative to GND) on this pin. FB (Pin L6): Apply a resistor from this pin to GND to set the output voltage, using the recommended value given in Table 1. If Table 1 does not list the desired VOUT value, the equation ( ) RFB = 31.6 VOUT –0.84 kΩ may be used to approximate the value. To the seasoned designer, this exponential equation may seem unusual. The equation is exponential due to non-linear current sources that are used to temperature compensate the output regulation. 8046fb 8 For more information www.linear.com/LTM8046 LTM8046 Block Diagram VOUT VIN • • 0.1µF 1µF RUN BIAS* SS VOUT– CURRENT MODE CONTROLLER FB GND 8046 BD *DO NOT ALLOW BIAS VOLTAGE TO EXCEED VIN Operation The LTM8046 is a stand-alone isolated flyback switching DC/DC µModule converter that can deliver over 700mA of output current. This module provides a regulated output voltage programmable via one external resistor from 1.8V to 12V. The input voltage range of the LTM8046 is 3.1V to 31V. Given that the LTM8046 is a flyback converter, the output current depends upon the input and output voltages, so make sure that the input voltage is high enough to support the desired output voltage and load current. The Typical Performance Characteristics section gives several graphs of the maximum load versus VIN for several output voltages. A simplified block diagram is given. The LTM8046 contains a current mode controller, power switching element, power transformer, power Schottky diode, a modest amount of input and output capacitance. The LTM8046 has a galvanic primary to secondary isolation rating of 2kVAC. This is verified by applying 3kVDC between the primary to secondary for 1 second. Note that the 2kVAC isolation is verified by a 3kVDC test. This is because the 2kVAC waveform has a peak voltage 1.414 times higher than 2kV, or 2.83kVDC. For the LTM8046, at least 3kVDC is applied. For further details please refer to the Isolation and Working Voltage section. 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 3.1V, bias power will be drawn from the external source, improving efficiency. VBIAS must not exceed VIN. The RUN pin is used to turn on or off the LTM8046, disconnecting the output and reducing the input current to 1μA or less. The LTM8046 is a variable frequency device. For a fixed input and output voltage, the frequency decreases as the load increases. For light loads, the current through the internal transformer may be discontinuous, so that frequency may appear to decrease. Note that a minimum load is required to keep the output voltage in regulation. Refer to the Typical Performance Characteristics section. 8046fb For more information www.linear.com/LTM8046 9 LTM8046 Applications Information For most applications, the design process is straightforward, 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 and RFB. 3.Connect BIAS as indicated, or tie to an external source up to 15V or VIN, whichever is less. 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 may be 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. 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. 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. A final precaution regarding ceramic capacitors concerns the maximum input voltage rating of the LTM8046. A ceramic input capacitor combined with trace or cable inductance forms a high-Q (underdamped) tank circuit. If the LTM8046 circuit is plugged into a live supply, the input voltage can ring to much higher than its nominal value, possibly exceeding the device’s rating. This situation is easily avoided; see the Hot-Plugging Safely section. Table 1. Recommended Components and Configuration (TA = 25°C) VIN VOUT CIN COUT RFB 3.2V to 32V 1.8V 1µF, 50V, 0805 X5R 2 × 100µF, 6.3V, 1206 X5R 18.7k 3.2V to 31V 2.5V 1µF, 50V, 0805 X5R 2 × 100µF, 6.3V, 1206 X5R 14.7k 3.2V to 29V 3.3V 1µF, 50V, 0805 X5R 100µF, 6.3V, 1206 X5R 11.8k 3.2V to 26V 5V 1µF, 25V, 0603 X5R 100µF, 6.3V, 1206 X5R 8.45k 3.2V to 20V 8V 1µF, 25V, 0603 X5R 47µF, 10V, 1206 X5R 5.49k 3.2V to 12V 12V 1µF, 25V, 0603 X5R 2 × 10µF, 16V, 1210 X5R 3.83k 3.2V to 25V 2.5V 1µF, 25V, 0603 X5R 2 × 100µF, 6.3V, 1206 X5R 14.7k 3.2V to 25V 3.3V 1µF, 25V, 0603 X5R 100µF, 6.3V, 1206 X5R 11.8k CBIAS = 1µF 10V 0402 X5R BIAS = 3.3V for VIN ≥ 3.3V, VIN for VIN < 3.3V. If BIAS = VIN, the minimum input voltage is 4.3V. 8046fb 10 For more information www.linear.com/LTM8046 LTM8046 Applications Information BIAS Pin Considerations The BIAS pin is the output of an internal linear regulator that powers the LTM8046’s internal circuitry. It is set to 3V and must be decoupled with a low ESR capacitor of at least 1μF. The LTM8046 will run properly without applying a voltage to this pin, but will operate more efficiently and dissipate less power if a voltage greater than 3.1V is applied. At low VIN, the LTM8046 will be able to deliver more output current if BIAS is 3.1V or greater. Up to 31V may be applied to this pin, but a high BIAS voltage will cause excessive power dissipation in the internal circuitry. For applications with an input voltage less than 15V, the BIAS pin is typically connected directly to the VIN pin. For input voltages greater than 15V, it is preferred to leave the BIAS pin separate from the VIN pin, either powered from a separate voltage source or left running from the internal regulator. This has the added advantage of keeping the physical size of the BIAS capacitor small. Do not allow BIAS to rise above VIN. Soft-Start For many applications, it is necessary to minimize the inrush current at start-up. The built-in soft-start circuit significantly reduces the start-up current spike and output voltage overshoot by applying a capacitor from SS to GND. When the LTM8046 is enabled, whether from VIN reaching a sufficiently high voltage or RUN being pulled high, the LTM8046 will source approximately 8µA out of the SS pin. As this current gradually charges the capacitor from SS to GND, the LTM8046 will correspondingly increase the power delivered to the output, allowing for a graceful turn-on ramp. Isolation Working Voltage and Safety The LTM8046 isolation is 100% hi-pot tested by tying all of the primary pins together, all of the secondary pins together and subjecting the two resultant circuits to a differential of 3kVDC for one second. This establishes the isolation voltage rating of the LTM8046 component. The isolation rating of the LTM8046 is not the same as the working or operational voltage that the application will experience. This is subject to the application’s power source, operating conditions, the industry where the end product is used and other factors that dictate design requirements such as the gap between copper planes, traces and component pins on the printed circuit board, as well as the type of connector that may be used. To maximize the allowable working voltage, the LTM8046 has three rows of solder balls removed to facilitate the printed circuit board design. The ball to ball pitch is 1.27mm, and the typical ball diameter is 0.78mm. Accounting for the missing row and the ball diameter, the printed circuit board may be designed for a metal-to-metal separation of up to 4.3mm. This may have to be reduced somewhat to allow for tolerances in solder mask or other printed circuit board design rules. To reiterate, the manufacturer’s isolation voltage rating and the required operational voltage are often different numbers. In the case of the LTM8046, the isolation voltage rating is established by 100% hi-pot testing. The working or operational voltage is a function of the end product and its system level specifications. The actual required operational voltage is often smaller than the manufacturer’s isolation rating. For those situations where information about the spacing of LTM8046 internal circuitry is required, the minimum metal to metal separation of the primary and secondary is 1.9mm. The LTM8046 is a UL recognized component under UL 60950-1, file number E464570. The UL 60950-1 insulation category of the LTM8046 transformer is Functional. Considering UL 60950-1 Table 2N and the gap distances stated above, 4.3mm external and 1.9mm internal, the LTM8046 may be operated with up to 400V working voltage in a pollution degree 2 environment. The actual working voltage, insulation category, pollution degree and other critical parameters for the specific end application depend upon the actual environmental, application and safety compliance requirements. It is therefore up to the user to perform a safety and compliance review to ensure that the LTM8046 is suitable for the intended application. 8046fb For more information www.linear.com/LTM8046 11 LTM8046 Applications Information VOUT to VOUT– Reverse Voltage VOUT– The LTM8046 cannot tolerate a reverse voltage from VOUT to VOUT– during operation. If VOUT– raises above VOUT during operation, the LTM8046 may be damaged. To protect against this condition, a low forward drop power Schottky diode has been integrated into the LTM8046, anti-parallel to VOUT/VOUT–. This can protect the output against many reverse voltage faults. Reverse voltage faults can be both steady state and transient. An example of a steady state voltage reversal is accidentally misconnecting a powered LTM8046 to a negative voltage source. An example of transient voltage reversals is a momentary connection to a negative voltage. It is also possible to achieve a VOUT reversal if the load is short-circuited through a long cable. The inductance of the long cable forms an LC tank circuit with the VOUT capacitance, which drives VOUT negative. Avoid these conditions. Minimum Load GND FB SS BIAS RUN VOUT THERMAL/INTERCONNECT VIAS VIN GND 8046 F01 Figure 1. Layout Showing Suggested External Components, Planes and Thermal Vias Figure 1 for a suggested layout. Ensure that the grounding and heat sinking are acceptable. The LTM8046 requires a minimum load in order to maintain regulation. If less than the minimum load is applied, the output voltage may rise beyond the intended value uncontrollably, possibly damaging the LTM8046 or the application system. Avoid this situation. The Typical Performance Characteristics section provides graphs of the minimum required load for several input and output conditions at room temperature. A few rules to keep in mind are: The LTM8046 is designed to skip switching cycles, if necessary, to maintain regulation. While cycle skipping, the output ripple may be higher than when the LTM8046 is not skipping cycles. The user must validate the performance of the LTM8046 application over the appropriate temperature, line, load and other operating conditions. 4.Place the CIN and COUT capacitors such that their ground current flow directly adjacent or underneath the LTM8046. 1.Place the RADJ resistor as close as possible to its respective pin. 2.Place the CIN capacitor as close as possible to the VIN and GND connections of the LTM8046. 3.Place the COUT capacitor as close as possible to VOUT and VOUT–. PCB Layout 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 LTM8046. Most of the headaches associated with PCB layout have been alleviated or even eliminated by the high level of integration of the LTM8046. The LTM8046 is nevertheless a switching power supply, and care must be taken to minimize electrical noise to ensure proper operation. Even with the high level of integration, you may fail to achieve specified operation with a haphazard or poor layout. See 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 1. The LTM8046 can benefit from the heat sinking afforded by vias that connect to internal 8046fb 12 For more information www.linear.com/LTM8046 LTM8046 Applications Information 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. The printed circuit board construction has an impact on the isolation performance of the end product. For example, increased trace and layer spacing, as well as the choice of core and prepreg materials (such as using polyimide versus FR4) can significantly affect the isolation withstand of the end product. Hot-Plugging Safely The small size, robustness and low impedance of ceramic capacitors make them an attractive option for the input bypass capacitor of the LTM8046. However, these capacitors can cause problems if the LTM8046 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 LTM8046 can ring to more than twice the nominal input voltage, possibly exceeding the LTM8046’s rating and damaging the part. If the input supply is poorly controlled or the user will be plugging the LTM8046 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 adding an electrolytic bulk capacitor to VIN. 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 can be a large component in the circuit. Thermal Considerations The LTM8046 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 LTM8046 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 FEA to predict thermal performance. To that end, the Pin Configuration section 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 θJB: 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 as follows: 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 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. 8046fb For more information www.linear.com/LTM8046 13 LTM8046 Applications Information 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 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 θJCbottom, this value may be useful for comparing packages but the test conditions don’t generally match the user’s application. 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. θJB is the junction-to-board thermal resistance where almost all of the heat flows through the bottom of the µModule converter 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 two-sided, two-layer board. This board is described in JESD 51-9. The blue resistances are contained within the µModule converter, and the green are outside. Given these definitions, it should now be apparent that none of these thermal coefficients reflects an actual physical operating condition of a µModule converter. Thus, none of them can be individually used to accurately predict the thermal performance of the product. Likewise, it would A graphical representation of these thermal resistances is given in Figure 2. The die temperature of the LTM8046 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 LTM8046. The bulk of the heat flow out of the LTM8046 is through the bottom of the module and the BGA 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 CASE (BOTTOM)-TO-BOARD JUNCTION-TO-CASE RESISTANCE (BOTTOM) RESISTANCE AMBIENT BOARD-TO-AMBIENT RESISTANCE 8046 F02 µMODULE DEVICE Figure 2. 8046fb 14 For more information www.linear.com/LTM8046 LTM8046 Typical Applications 3.3V Isolated Flyback Converter LTM8046 VIN 3.3V TO 29V VIN 3.3V BIAS 1µF 11.8k FB SS ISOLATION BARRIER RUN 1µF VOUT 3.3V VOUT 100µF VOUT– GND 2kVAC ISOLATION 8046 TA02a Maximum Output Current vs VIN MAXIMUM OUTPUT CURRENT (mA) 800 700 600 500 400 300 200 0 10 20 VIN (V) 30 8046 TA02b 8046fb For more information www.linear.com/LTM8046 15 LTM8046 Typical Applications Use Two LTM8046 Flyback Converters to Generate ±5V LTM8046 VIN 4.3V TO 26V 1µF VIN BIAS 8.45k FB SS 1µF ISOLATION BARRIER RUN 1µF 5V VOUT 100µF VOUT– GND 2kVAC ISOLATION 22µF LTM8046 VIN RUN BIAS 1µF 8.45k FB SS 1µF ISOLATION BARRIER 1µF VOUT 100µF VOUT– GND –5V 2kVAC ISOLATION 8046 TA03a Maximum Output Current vs VIN MAXIMUM OUTPUT CURRENT (mA) 700 600 500 400 300 200 100 0 5 10 15 VIN (V) 20 25 30 8046 TA03b 8046fb 16 For more information www.linear.com/LTM8046 LTM8046 Package Description Pin Assignment Table (Arranged by Pin Number) PIN NAME A1 VOUT A2 VOUT A3 VOUT A4 VOUT A5 VOUT– A6 VOUT– A7 VOUT– PIN NAME B1 VOUT B2 VOUT B3 VOUT B4 VOUT B5 VOUT– B6 VOUT– B7 VOUT– PIN NAME C1 VOUT– C2 VOUT– C3 VOUT– C4 VOUT– C5 VOUT– C6 VOUT– C7 VOUT– PIN NAME D1D2D3D4D5D6D7- PIN NAME E1E2E3E4E5E6E7- PIN NAME F1F2F3F4F5F6F7- PIN NAME G1 GND G2 GND G3 GND G4 GND G5 GND G6 GND G7 GND PIN NAME H1H2H3 GND H4 GND H5 GND H6 GND H7 GND PIN NAME J1 VIN J2J3 GND J4 GND J5 GND J6 GND J7 GND PIN NAME K1 VIN K2K3 GND K4 GND K5 GND K6 GND K7 GND PIN NAME L1 VIN L2L3 RUN L4 BIAS L5 SS L6 FB L7 GND Package Photo 8046fb For more information www.linear.com/LTM8046 17 0.630 ±0.025 Ø 51x SUGGESTED PCB LAYOUT TOP VIEW 2.540 PACKAGE TOP VIEW 1.270 4 0.3175 0.000 0.3175 PIN “A1” CORNER E 1.270 aaa Z 2.540 18 Y For more information www.linear.com/LTM8046 6.350 5.080 3.810 2.540 1.270 0.000 3.810 5.080 6.350 D X aaa Z // bbb Z SYMBOL A A1 A2 b b1 D E e F G H1 H2 aaa bbb ccc ddd eee H1 SUBSTRATE NOM 4.92 0.60 4.32 0.78 0.63 15.00 9.00 1.27 12.70 7.62 0.32 4.00 A A2 MAX 5.12 0.70 4.42 0.85 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: 51 0.27 3.95 MIN 4.72 0.50 4.22 0.71 0.60 b1 DIMENSIONS ddd M Z X Y eee M Z DETAIL A Øb (51 PLACES) DETAIL B H2 MOLD CAP ccc Z A1 Z (Reference LTC DWG# 05-08-1889 Rev Ø) Z b 3 F e SEE NOTES 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 BALL DESIGNATION PER JESD MS-028 AND JEP95 TRAY PIN 1 BEVEL BGA 51 1110 REV Ø PACKAGE IN TRAY LOADING ORIENTATION LTMXXXXXX µModule 6. SOLDER BALL COMPOSITION CAN BE 96.5% Sn/3.0% Ag/0.5% Cu OR Sn Pb EUTECTIC 5. PRIMARY DATUM -Z- IS SEATING PLANE 4 3 2. ALL DIMENSIONS ARE IN MILLIMETERS NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994 COMPONENT PIN “A1” BGA Package 51-Lead (15.00mm × 9.00mm × 4.92mm) LTM8046 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. 8046fb 3.810 3.810 LTM8046 Revision History REV DATE DESCRIPTION PAGE NUMBER A 07/14 Add MP-grade 2, 3 B 04/15 VIN changed from 32V to 31V 1 8046fb 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 representaFor more information www.linear.com/LTM8046 tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. 19 LTM8046 Typical Application Maximum Output Current vs VIN 12V Isolated Flyback Converter 1µF 3.3V BIAS 1µF 3.83k VOUT 12V VOUT RUN FB SS MAXIMUM OUTPUT CURRENT (mA) LTM8046 VIN ISOLATION BARRIER VIN 3.3VDC TO 12VDC 300 10µF ×2 VOUT– GND 2kVAC ISOLATION 250 200 150 100 50 8046 TA04 0 3 6 9 VIN (V) 12 8046 TA04b Design Resources SUBJECT DESCRIPTION µModule Design and Manufacturing Resources Design: • Selector Guides • Demo Boards and Gerber Files • Free Simulation Tools µModule Regulator Products Search 1. Sort table of products by parameters and download the result as a spread sheet. Manufacturing: • Quick Start Guide • PCB Design, Assembly and Manufacturing Guidelines • Package and Board Level Reliability 2. Search using the Quick Power Search parametric table. TechClip Videos Quick videos detailing how to bench test electrical and thermal performance of µModule 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. Related Parts PART NUMBER DESCRIPTION COMMENTS LTM8057 UL60950 Recognized 1.5W, 2kVAC Isolated µModule 3.1V ≤ VIN ≤ 31V, 2.5V ≤ VOUT ≤ 12V, 5% VOUT Accuracy, Internal Isolated Transformer, 9mm × 11.25mm × 4.92mm BGA Converter LTM8058 UL60950 Recognized 1.5W, 2kVAC Isolated µModule 3.1V ≤ VIN ≤ 31V, 1.2V ≤ VOUT ≤ 12V, 2.5% VOUT Accuracy, 1mVP-P Output Ripple, Internal Isolated Transformer, 9mm × 11.25mm × 4.92mm BGA Converter with LDO Post Regulator LTM8048 1.5W, 725VDC Galvanically Isolated µModule Converter with LDO Post Regulator 3.1V ≤ VIN ≤ 32V, 1.2V ≤ VOUT ≤ 12V, 2.5% VOUT Accuracy, 1mVP-P Output Ripple, Internal Isolated Transformer, 9mm × 11.25mm × 4.92mm BGA LTM8045 Inverting or SEPIC μModule DC/DC Converter with Up to 700mA Output Current 2.8V ≤ VIN ≤ 18V, ±2.5V ≤ VOUT ≤ ±15V, Synchronizable, No Derating or Logic Level Shift for Control Inputs When Inverting, 6.25mm × 11.25mm × 4.92mm BGA LTM4609 36VIN, 5A DC/DC μModule Buck-Boost Regulator 4.5V ≤ VIN ≤ 36V, 0.8V ≤ VOUT ≤ 34V, Adjustable Soft-Start, Clock Input, 15mm × 15mm × 2.82mm LGA and 15mm × 15mm × 3.42mm BGA LTM8061 32V, 2A Step-Down μModule Battery Charger with Programmable Input Current Limit Suitable for Charging Single and Dual Cell Li-Ion or Li-Poly Batteries, 4.95V ≤ VIN ≤ 32V, C/10 or Adjustable Timer Charge Termination, NTC Resistor Monitor Input, 9mm × 15mm × 4.32mm LGA 8046fb 20 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LTM8046 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LTM8046 LT 0415 REV B • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 2014