VTMTM Current Multiplier VTM48Ex120y025A00 S C NRTL US High-Efficiency Sine Amplitude ConverterTM Features & Benefits Product Ratings * 48VDC to 12VDC 25A current multiplier Operating from standard 48V or 24V PRMTM Regulators * High efficiency (>96%) reduces system power consumption * High density (85A/in3) VIN = 26 - 55V IOUT = 25A (Nominal) VOUT = 6.5 - 13.8V (No Load) K = 1/4 Product Description The VI Chip(R) current multiplier is a high-efficiency (>96%) Sine Amplitude ConverterTM (SAC) operating from a 26 to 55VDC primary bus to deliver an isolated output. The Sine Amplitude Converter offers a low AC impedance beyond the bandwidth of most downstream regulators; therefore capacitance normally at the load can be located at the input to the Sine Amplitude Converter. Since the K factor of the VTM48EF120T025A00 is 1/4, the capacitance value can be reduced by a factor of 16, resulting in savings of board area, materials and total system cost. * "Full Chip" VI Chip(R) package enables surface mount, low-impedance interconnect to system board * Contains built-in protection features against: Overvoltage Lockout Overcurrent Short Circuit Overtemperature * Provides enable / disable control, internal temperature monitoring The VTM48EF120T025A00 is provided in a VI Chip package compatible with standard pick-and-place and surface mount assembly processes. The co-molded VI Chip package provides enhanced thermal management due to a large thermal interface area and superior thermal conductivity. The high conversion efficiency of the VTM48EF120T025A00 increases overall system efficiency and lowers operating costs compared to conventional approaches. * ZVS / ZCS resonant Sine Amplitude Converter topology * Less than 50C temperature rise at full load in typical applications Typical Applications The VTM48EF120T025A00 enables the utilization of Factorized Power ArchitectureTM which provides efficiency and size benefits by lowering conversion and distribution losses and promoting highdensity point-of-load conversion. * High-End Computing Systems * Automated Test Equipment * High-Density Power Supplies Part Numbering * Communications Systems Product Number Package Style (x) VTM48Ex120y025A00 F = J-Lead T = -40 to 125C T = Through hole M = -55 to 125C For Storage and Operating Temperatures see General Characteristics Section Typical Application Regulator Voltage Transformer VC SG OS CD PR PC TM IL Product Grade (y) TM VC PC VTMTM Transformer PRMTM Regulator +IN +OUT -IN -OUT +IN +OUT -IN -OUT VIN VTMTM Current Multiplier Page 1 of 19 Factorized Power ArchitectureTM Rev 3.6 07/2018 L O A D (See Application Note AN:024) VTM48Ex120y025A00 Absolute Maximum Ratings The absolute maximum ratings below are stress ratings only. Operation at or beyond these maximum ratings can cause permanent damage to the device. Parameter Comments Min Max Unit +IN to -IN -1.0 60 VDC PC to -IN -0.3 20 VDC TM to -IN -0.3 7 VDC VC to -IN -0.3 20 VDC 2250 VDC 16 VDC +IN / -IN to +OUT / -OUT (hipot) +OUT to -OUT -1.0 Electrical Specifications Specifications apply over all line and load conditions unless otherwise noted; boldface specifications apply over the temperature range of -40C < TJ < 125C (T-Grade). All other specifications are at TJ = 25C unless otherwise noted. Attribute Symbol Conditions / Notes Min Typ Max Unit Powertrain Input Voltage Range VIN Slew Rate VIN UV Turn Off VIN No external VC applied 26 55 VC applied 0 55 dVIN / dt VIN_UV Module latched shutdown, No external VC applied, IOUT = 25A 3 VIN = 48V No Load Power Dissipation PNL 24 IINRP DC Input Current IIN_DC Transfer Ratio Output Voltage Output Current (Average) Output Current (Peak) Output Power (Average) Efficiency (Ambient) K VOUT 5.3 POUT_AVG AMB Efficiency (Hot) HOT Efficiency (Over Load Range) 20% VTMTM Current Multiplier Page 2 of 19 26 V 6.5 W 9 VC enable, VIN = 48V, COUT = 1000F, RLOAD = 471m 10 K = VOUT / VIN, IOUT = 0A 20 A 7 A 1/4 V/V VOUT = VIN * K - IOUT * ROUT V 25 A tPEAK < 10ms, IOUT_AVG 25A 37.5 A IOUT_AVG 25A 300 W IOUT_AVG IOUT_PK V / s 17 VIN = 26 - 55V, TC = 25C Inrush Current Peak 1 15 VIN = 26 - 55V VIN = 48V, TC = 25C VDC VIN = 48V, IOUT = 25A 95.0 VIN = 26 - 55V, IOUT = 25A 93.5 VIN = 48V, IOUT = 12.5A 94.5 95.5 VIN = 48V, TC = 100C, IOUT = 25A 94.5 95.6 80 5A < IOUT < 25A Rev 3.6 07/2018 96.0 % % % VTM48Ex120y025A00 Electrical Specifications (Cont.) Specifications apply over all line and load conditions unless otherwise noted; boldface specifications apply over the temperature range of -40C < TJ < 125C (T-Grade). All other specifications are at TJ = 25C unless otherwise noted. Attribute Symbol Conditions / Notes Min Typ Max Unit Powertrain (Cont.) Output Resistance (Cold) ROUT_COLD TC = -40C, IOUT = 25A 4.9 7.5 12.0 m Output Resistance (Ambient) ROUT_AMB TC = 25C, IOUT = 25A 6.3 9.0 14.0 m Output Resistance (Hot) ROUT_HOT TC = 100C, IOUT = 25A 8.8 11.5 16.0 m 1.85 1.95 2.05 MHz 3.70 Switching Frequency FSW 3.90 4.10 MHz VOUT_PP Cout = 0F, Iout = 25A, Vin = 48V, 20MHz BW 150 285 mV Output Inductance (Parasitic) LOUT_PAR Frequency up to 30MHz, Simulated J-lead model 600 pH Output Capacitance (Internal) COUT_INT Effective Value at 12Vout 47 F COUT_EXT VTM Standalone Operation. Vin pre-applied, VC enable Output Ripple Frequency Output Voltage Ripple Output Capacitance (External) FSW_RP 1000 F 60 V Protection Overvoltage Lockout 55.1 VIN_OVLO+ Module latched shutdown Overvoltage Lockout Response Time Constant tOVLO Effective internal RC filter Output Overcurrent Trip IOCP 33 Short Circuit Protection Trip Current ISCP 39 Output Overcurrent Response Time Constant tOCP Effective internal RC filter (Integrative) Short Circuit Protection Response Time tSCP From detection to cessation of switching (Instantaneous) Thermal Shutdown Set Point Reverse Inrush Current Protection VTMTM Current Multiplier Page 3 of 19 TJ_OTP 125 Reverse Inrush protection is disabled for this product Rev 3.6 07/2018 58.5 8 s 47 A A 5.3 ms 1 s 130 135 C VTM48Ex120y025A00 Signal Characteristics Specifications apply over all line and load conditions unless otherwise noted; boldface specifications apply over the temperature range of -40C TJ < 125C (T-Grade). All other specifications are at TJ = 25C unless otherwise noted. VTM Control: VC * * * * * * Used to wake up powertrain circuit. A minimum of 11.5V must be applied indefinitely for Vin < 26V to ensure normal operation. VC slew rate must be within range for a successful start. PRMTM VC can be used as valid wake-up signal source. Internal Resistance used in "Adaptive Loop" compensation. VC voltage may be continuously applied. Signal Type State Attribute External VC Voltage VC Current Draw Symbol VVC_EXT IVC Steady ANALOG Start Up Typ 11.5 VC = 11.5V, VIN = 0V 130 VC = 11.5V, VIN > 26V 25 VC = 16.5V, VIN > 26V 115 Fault mode. VC > 11.5V Max Unit 16.5 V 150 mA 60 DVC_INT 100 V VC Internal Resistor RVC-INT 0.511 k TVC_COEFF 3900 ppm/C VC Start-Up Pulse VVC_SP tPEAK < 18ms VC Slew Rate dVC/dt Required for proper start up VC Inrush Current IINR_VC VC = 16.5V, dVC/dt = 0.25V/s VC to VOUT Turn-On Delay Transitional Min VC Internal Diode Rating VC Internal Resistor Temperature Coefficient INPUT Conditions / Notes Required for start up and operation below 26V. 0.02 VIN pre-applied, PC floating, VC enable, CPC = 0F tON VC to PC Delay tVC_PC VC = 11.5V to PC high, VIN = 0V, dVC/dt = 0.25V/s 75 Internal VC Capacitance CVC_INT VC = 0V 3.2 20 V 0.25 V / s 1 A 500 s 125 s F Primary Control: PC * * * * * * The PC pin enables and disables the VTM. When held below 2V, the VTM will be disabled. PC pin outputs 5V during normal operation. PC pin is equal to 2.5V during fault mode given Vin > 26V or VC > 11.5V. After successful start up and under no-fault condition, PC can be used as a 5V regulated voltage source with a 2mA maximum current. Module will shutdown when pulled low with an impedance less than 400. In an array of VTMs, connect PC pin to synchronize start up. PC pin cannot sink current and will not disable other modules during fault mode. Signal Type State Attribute PC Voltage Symbol PC Source Current IPC_OP ANALOG PC Resistance (Internal) RPC_INT OUTPUT PC Source Current Steady Start Up Enable DIGITAL INPUT / OUTPUT Disable Transitional VTMTM Current Multiplier Page 4 of 19 PC Capacitance (Internal) Conditions / Notes VPC Internal pull-down resistor IPC_EN Min Typ Max Unit 4.7 5.0 5.3 V 2 mA 400 k 300 A 1000 pF 50 150 50 100 CPC_INT PC Resistance (External) RPC_S 60 PC Voltage VPC_EN 2 PC Voltage (Disable) VPC_DIS PC Pull-Down Current PC Disable Time PC Fault-Response Time 2.5 5.1 IPC_PD tPC_DIS_T tFR_PC k From fault to PC = 2V Rev 3.6 07/2018 3 V 2 V mA 5 s 100 s VTM48Ex120y025A00 Signal Characteristics (Cont.) Specifications apply over all line and load conditions unless otherwise noted; boldface specifications apply over the temperature range of -40C TJ < 125C (T-Grade). All other specifications are at TJ = 25C unless otherwise noted. Temperature Monitor: TM * * * * The TM pin monitors the internal temperature of the VTM controller IC within an accuracy of 5C. Can be used as a "Power Good" flag to verify that the VTM is operating. The TM pin has a room-temperature set point of 3V and approximate gain of 10mV/C. Output drives Temperature Shutdown comparator. Signal Type State Attribute TM Voltage ANALOG OUTPUT DIGITAL OUTPUT (FAULT FLAG) Steady Disable Transitional VTMTM Current Multiplier Page 5 of 19 Symbol VTM_AMB TM Source Current ITM TM Gain ATM VTM_PP TM Voltage VTM_DIS TM Resistance (Internal) RTM_INT TM Capacitance (External) CTM_EXT tFR_TM Min Typ Max Unit 2.95 3.00 3.05 V 100 A 10 TM Voltage Ripple TM Fault-Response Time Conditions / Notes TJ controller = 27C CTM = 0F, VIN = 48V, IOUT = 25A 120 mV/C 200 mV 50 k 50 pF 0 Internal pull-down resistor From fault to TM = 1.5V Rev 3.6 07/2018 25 40 10 V s VTM48Ex120y025A00 Timing Diagram ISEC 7 6 ISEC ISEC 1 2 3 VC 4 8 d 5 b VVC-EXT a VPRI VOVLO NL 26V c e f VSEC TM VTM-AMB PC g 5V 3V a: VC slew rate (dVC/dt) b: Minimum VC pulse rate c: tOVLO_PIN d: tOCP_SEC e: Secondary turn on delay (tON) f: PC disable time (tPC_DIS_t) g: VC to PC delay (tVC_PC) VTMTM Current Multiplier Page 6 of 19 1. Initiated VC pulse 2. Controller start 3. VPRI ramp up 4. VPRI = VOVLO 5. VPRI ramp down no VC pulse 6. Overcurrent, Secondary 7. Start up on short circuit 8. PC driven low Rev 3.6 07/2018 Notes: - Timing and voltage is not to scale - Error pulse width is load dependent VTM48Ex120y025A00 Application Characteristics The following values, typical of an application environment, are collected at TC = 25C unless otherwise noted. See associated figures for general trend data. Attribute Symbol Conditions / Notes Typ Unit Powertrain No-Load Power Dissipation PNL VIN = 48V, PC enabled 5.1 W Efficiency (Ambient) AMB VIN = 48V, IOUT = 25A 96.0 % Efficiency (Hot) HOT VIN = 48V, IOUT = 25A, TC = 100C 95.6 % Output Resistance (Cold) ROUT_COLD VIN = 48V, IOUT = 25A, TC = -40C 7.4 m Output Resistance (Ambient) ROUT_AMB VIN = 48V, IOUT = 25A 9.4 m Output Resistance (Hot) ROUT_HOT VIN = 48V, IOUT = 25A, TC = 100C 11.7 m Output Voltage Ripple VOUT_PP COUT = 0F, IOUT = 25A, VIN = 48V, 20MHz BW 198 mV VOUT Transient (Positive) VOUT_TRAN+ IOUT_STEP = 0 - 25A, VIN = 48V, ISLEW = 23A/s 650 mV VOUT Transient (Negative) VOUT_TRAN- IOUT_STEP = 25 - 0A, VIN = 48V, ISLEW = 91A/s 310 mV 100 Full Load Efficiency (%) Power Dissipation (W) 11 9 7 5 3 1 26 29 32 35 38 41 43 46 49 52 99 98 97 96 95 94 93 92 91 90 -40 55 -20 0 -40C TCASE: 25C 100C Figure 1 -- No load power dissipation vs. Vin 26V VIN: 40 60 80 100 48V 55V Figure 2 -- Full load efficiency vs. temperature 50 96 45 Power Dissipation (W) 100 92 Efficiency (%) 20 Case Temperature (C) Input Voltage (V) 88 84 80 76 72 68 64 60 40 35 30 25 20 15 10 5 0 0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 0.0 2.5 5.0 Load Current (A) VIN: 26V Figure 3 -- Efficiency at -40C VTMTM Current Multiplier Page 7 of 19 48V 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 Load Current (A) 55V VIN: 26V Figure 4 -- Power dissipation at -40C Rev 3.6 07/2018 48V 55V VTM48Ex120y025A00 Application Characteristics (Cont.) The following values, typical of an application environment, are collected at TC = 25C unless otherwise noted. See associated figures for general trend data. 96 28 Power Dissipation (W) 32 Efficiency (%) 100 92 88 84 80 76 72 68 24 20 16 12 8 4 0 0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 0.0 2.5 5.0 7.5 Load Current (A) 26V VIN: 48V 55V 48V 55V Figure 6 -- Power dissipation at 25C 32 96 28 Power Dissipation (W) 100 Efficiency (%) 26V VIN: Figure 5 -- Efficiency at 25C 92 88 84 80 76 72 68 24 20 16 12 8 4 0 0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 0.0 2.5 5.0 7.5 Load Current (A) 26V VIN: 48V 55V 26V VIN: 48V 55V Figure 8 -- Power dissipation at 100C 14 250 13 225 VRIPPLE (mVPK-PK) 12 11 10 9 8 7 6 200 175 150 125 100 75 5 4 -40 10.0 12.5 15.0 17.5 20.0 22.5 25.0 Load Current (A) Figure 7 -- Efficiency at 100C ROUT (m) 10.0 12.5 15.0 17.5 20.0 22.5 25.0 Load Current (A) 50 -20 0 40 20 60 80 100 0.0 2.5 5.0 Case Temperature (C) IOUT: Figure 9 -- Rout vs. temperature VTMTM Current Multiplier Page 8 of 19 12.5A 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 Load Current (A) 25A VIN: 26V 48V 55V Figure 10 -- Vripple vs. Iout; No external Cout. Board mounted module, scope setting: 20MHz analog BW Rev 3.6 07/2018 VTM48Ex120y025A00 Application Characteristics (Cont.) The following values, typical of an application environment, are collected at TC = 25C unless otherwise noted. See associated figures for general trend data. 45 Output Current (A) 40 35 10ms max 30 25 20 Continuous 15 10 5 0 0 2 4 6 8 10 12 14 16 Output Voltage (V) Figure 11 -- Safe operating area Figure 12 -- Full load ripple, 100F Cin; No external Cout. Boardmounted module, scope setting: 20MHz analog BW Figure 13 -- Start up from application of Vin; VC pre-applied Cout = 1000F Figure 14 -- Start up from application of VC; Vin pre-applied Cout = 1000F Figure 15 -- 0A - Full load transient response: Cin = 100F, no external Cout Figure 16 -- Full load - 0A transient response: Cin = 100F, no external Cout VTMTM Current Multiplier Page 9 of 19 Rev 3.6 07/2018 VTM48Ex120y025A00 General Characteristics Specifications apply over all line and load conditions unless otherwise noted; boldface specifications apply over the temperature range of -40C < TJ < 125 C (T-Grade). All Other specifications are at TJ = 25C unless otherwise noted. Attribute Symbol Conditions / Notes Min Typ Max Unit Mechanical Length L 32.25 [1.270] 32.5 [1.280] 32.75 [1.289] mm [in] Width W 21.75 [0.856] 22.0 [0.866] 22.25 [0.876] mm [in] 6.48 [0.255] 6.73 [0.265] 6.98 [0.275] Height H Volume Vol Weight W Lead Finish No heat sink cm3 [in3] 15.0 [0.53] g [oz] Nickel 0.51 2.03 Palladium 0.02 0.15 0.003 0.051 VTM48EF120T025A00 (T-Grade) -40 125 VTM48EF120M025A00 (M-Grade) -55 125 VTM48ET120T025A00 (T-Grade) -40 125 VTM48ET120M025A00 (M-Grade) -55 125 Gold mm [in] 4.81 [0.294] m Thermal Operating Temperature Thermal Resistance TJ JC Isothermal heat sink and isothermal internal PCB Thermal Capacity C 1 C / W 5 Ws / C Assembly Peak Compressive Force Applied to Case (Z-Axis) Storage Temperature Supported by J-Lead only TST lbs 5.41 lbs / in2 VTM48EF120T025A00 (T-Grade) -40 125 VTM48EF120M025A00 (M-Grade) -65 125 VTM48ET120T025A00 (T-Grade) -40 125 VTM48ET120M025A00 (M-Grade) -65 125 ESDHBM Human Body Model, JEDEC JESD 22-A114-F 1000 ESDCDM Charge Device Model, JEDEC JESD 22-C101-D 400 ESD Withstand 6 C VDC Soldering Peak Temperature During Reflow 245 C Peak Time Above 217C MSL 4 (Datecode 1528 and later) 60 90 s Peak Heating Rate During Reflow 1.5 3 C / s 1.5 6 C / s 3200 3800 Peak Cooling Rate Post Reflow Safety Isolation Voltage (Hipot) VHIPOT Isolation Capacitance CIN_OUT Isolation Resistance RIN_OUT MTBF Agency Approvals / Standards VTMTM Current Multiplier Page 10 of 19 2250 2500 Unpowered unit VDC 10 pF M MIL-HDBK-217 Plus Parts Count; 25C Ground Benign, Stationary, Indoors / Computer Profile 6.03 MHrs Telcordia Issue 2 - Method I Case 1; Ground Benign, Controlled 7.94 MHrs cTUVus CE Marked for Low Voltage Directive and RoHS Recast Directive, as applicable Rev 3.6 07/2018 VTM48Ex120y025A00 Using the Control Signals VC, PC, TM Start-Up Behavior The VTM Control (VC) pin is an input pin which powers the internal VCC circuitry when within the specified voltage range of 11.5 - 16.5V. This voltage is required for VTM current multiplier start up and must be applied as long as the input is below 26V. In order to ensure a proper start, the slew rate of the applied voltage must be within the specified range. Depending on the sequencing of the VC with respect to the input voltage, the behavior during start up will vary as follows: Some additional notes on the using the VC pin: nn In most applications, the VTM module will be powered by an upstream PRMTM regulator which provides a 10ms VC pulse during start up. In these applications the VC pins of the PRM regulator and VTM current multiplier should be tied together. nn The VC voltage can be applied indefinitely allowing for continuous operation down to 0VIN. nn The fault response of the VTM module is latching. A positive edge on VC is required in order to restart the unit. If VC is continuously applied the PC pin may be toggled to restart the VTM module. Primary Control (PC) pin can be used to accomplish the following functions: nn Delayed start: Upon the application of VC, the PC pin will source a constant 100A current to the internal RC network. Adding an external capacitor will allow further delay in reaching the 2.5V threshold for module start. nn Auxiliary voltage source: Once enabled in regular operational conditions (no fault), each VTM PC provides a regulated 5V, 2mA voltage source. nn Output disable: PC pin can be actively pulled down in order to disable the module. Pull-down impedance shall be lower than 400. nn Normal operation (VC applied prior to Vin ): In this case the controller is active prior to ramping the input. When the input voltage is applied, the VTM module output voltage will track the input (See Figure 13). The inrush current is determined by the input voltage rate of rise and output capacitance. If the VC voltage is removed prior to the input reaching 26V, the VTM may shut down. nn Stand-alone operation (VC applied after Vin ): In this case the VTM output will begin to rise upon the application of the VC voltage (See Figure 14). The Adaptive Soft-Start Circuit may vary the output rate of rise in order to limit the inrush current to its maximum level. When starting into high capacitance or a short, the output current will be limited for a maximum of 1200s. After this period, the Adaptive Soft-Start Circuit will time out and the VTM module may shut down. No restart will be attempted until VC is reapplied or PC is toggled. The maximum output capacitance is limited to 1000F in this mode of operation to ensure a successful start. Thermal Considerations VI Chip(R) products are multi-chip modules whose temperature distribution varies greatly for each part number as well as with the input / output conditions, thermal management and environmental conditions. Maintaining the top of the VTM48EF120T025A00 case to less than 100C will keep all junctions within the VI Chip module below 125C for most applications. nn Fault detection flag: The PC 5V voltage source is internally turned off as soon as a fault is detected. It is important to notice that PC doesn't have current sink capability. Therefore, in an array, PC line will not be capable of disabling neighboring modules if a fault is detected. The percent of total heat dissipated through the top surface versus through the J-lead is entirely dependent on the particular mechanical and thermal environment. The heat dissipated through the top surface is typically 60%. The heat dissipated through the J-lead onto the PCB board surface is typically 40%. Use 100% top surface dissipation when designing for a conservative cooling solution. nn Fault reset: PC may be toggled to restart the unit if VC is continuously applied. It is not recommended to use a VI Chip module for an extended period of time at full load without proper heat sinking. Temperature Monitor (TM) pin provides a voltage proportional to the absolute temperature of the converter control IC. It can be used to accomplish the following functions: nn Monitor the control IC temperature: The temperature in Kelvin is equal to the voltage on the TM pin scaled by 100. (i.e., 3.0V = 300K = 27C). If a heat sink is applied, TM can be used to thermally protect the system. nn Fault detection flag: The TM voltage source is internally turned off as soon as a fault is detected. For system monitoring purposes (microcontroller interface) faults are detected on falling edges of TM signal. VTMTM Current Multiplier Page 11 of 19 Rev 3.6 07/2018 VTM48Ex120y025A00 Sine Amplitude ConverterTM Point-of-Load Conversion The Sine Amplitude Converter (SAC) uses a high-frequency resonant tank to move energy from input to output. (The resonant tank is formed by Cr and leakage inductance Lr in the power transformer windings.) The resonant LC tank, operated at high frequency, is amplitude modulated as a function of input voltage and output current. A small amount of capacitance embedded in the input and output stages of the module is sufficient for full functionality and is key to achieving power density. The VTM48EF120T025A00 SAC can be simplified into the following model: 973pH + RCCIN IN 0.57m VVIN IN CIN C2F IN ROUT ROUT 9.0m IOUT IOUT LIN = 5.7nH IQIQ 109mA 1/4 * IOUT + - K + R RCC OUT OUT 3.13 V*I + LOUT = 600pH 430 1/4 * VIN COUT COUT 47F OUT VVOUT - - - Figure 17 -- VI Chip(R) module AC model At no load: VOUT = VIN * K The use of DC voltage transformation provides additional interesting attributes. Assuming that ROUT = 0 and IQ = 0A, Equation 3 now becomes Equation 1 and is essentially load independent, resistor R is now placed in series with VIN as shown in Figure 18. (1) K represents the "turns ratio" of the SAC. Rearranging Equation 1: K= VOUT (2) VIN RIN In the presence of load, VOUT is represented by: VOUT = VIN * K - IOUT * ROUT VIN IOUT = K SACTM K = 1/32 (4) Figure 18 -- K = 1/32 Sine Amplitude ConverterTM with series input resistor The relationship between VIN and VOUT becomes: ROUT represents the impedance of the SAC, and is a function of the RDSON of the input and output MOSFETs and the winding resistance of the power transformer. IQ represents the quiescent current of the SAC control and gate drive circuitry. VOUT = (VIN - IIN * R) * K (5) Substituting the simplified version of Equation 4 (IQ is assumed = 0A) into Equation 5 yields: VOUT = VIN * K - IOUT * R * K2 VTMTM Current Multiplier Page 12 of 19 VOUT (3) and IOUT is represented by: IIN - IQ + - Rev 3.6 07/2018 (6) VTM48Ex120y025A00 This is similar in form to Equation 3, where ROUT is used to represent the characteristic impedance of the SACTM. However, in this case a real R on the input side of the SAC is effectively scaled by K 2 with respect to the output. Assuming that R = 1, the effective R as seen from the secondary side is 0.98m, with K = 1/32 as shown in Figure 18. A similar exercise should be performed with the additon of a capacitor or shunt impedance at the input to the SAC. A switch in series with VIN is added to the circuit. This is depicted in Figure 19. A solution for keeping the impedance of the SAC low involves switching at a high frequency. This enables small magnetic components because magnetizing currents remain low. Small magnetics mean small path lengths for turns. Use of low-loss core material at high frequencies also reduces core losses. S VIN + - C SACTM K = 1/32 Low impedance is a key requirement for powering a highcurrent, lowvoltage load efficiently. A switching regulation stage should have minimal impedance while simultaneously providing appropriate filtering for any switched current. The use of a SAC between the regulation stage and the point-of-load provides a dual benefit of scaling down series impedance leading back to the source and scaling up shunt capacitance or energy storage as a function of its K factor squared. However, the benefits are not useful if the series impedance of the SAC is too high. The impedance of the SAC must be low, i.e., well beyond the crossover frequency of the system. VOUT The two main terms of power loss in the VTM module are: nn No load power dissipation (PNL): defined as the power used to power up the module with an enabled powertrain at no load. nn Resistive loss (ROUT): refers to the power loss across the VTM modeled as pure resistive impedance. Figure 19 -- Sine Amplitude ConverterTM with input capacitor PDISSIPATED = PNL + PR A change in VIN with the switch closed would result in a change in capacitor current according to the following equation: IC (t) = C dVIN (7) dt Therefore, POUT = PIN - PDISSIPATED = PIN - PNL - PR OUT Assume that with the capacitor charged to VIN, the switch is opened and the capacitor is discharged through the idealized SAC. In this case, IC = IOUT * K C (8) K2 * dVOUT dt (9) The equation in terms of the output has yielded a K 2 scaling factor for C, specified in the denominator of the equation. A K factor less than unity results in an effectively larger capacitance on the output when expressed in terms of the input. With a K = 1/32 as shown in Figure 19, C = 1F would appear as C = 1024F when viewed from the output. VTMTM Current Multiplier Page 13 of 19 (11) The above relations can be combined to calculate the overall module efficiency: = Substituting Equations 1 and 8 into Equation 7 reveals: IOUT = (10) OUT Rev 3.6 07/2018 = POUT PIN = PIN - PNL - PR PIN OUT VIN * IIN - PNL - (IOUT)2 * ROUT =1- VIN * IIN ( ) PNL + (IOUT)2 * ROUT VIN * IIN (12) VTM48Ex120y025A00 Input and Output Filter Design A major advantage of a SAC system versus a conventional PWM converter is that the former does not require large functional filters. The resonant LC tank, operated at extreme high frequency, is amplitude modulated as a function of input voltage and output current and efficiently transfers charge through the isolation transformer. A small amount of capacitance embedded in the input and output stages of the module is sufficient for full functionality and is key to achieving high power density. This paradigm shift requires system design to carefully evaluate external filters in order to: A Sine Amplitude Converter has a DC ROUT value which has already been discussed on Page 12. The AC ROUT of the SAC contains several terms: nn Input lead inductance and internal capacitance To take full advantage of the VTM module dynamic response, the impedance presented to its input terminals must be low from DC to approximately 5MHz. Input capacitance may be added to improve transient performance or compensate for high source impedance. nn Further reduce input and/or output voltage ripple without sacrificing dynamic response: Given the wide bandwidth of the VTM module, the source response is generally the limiting factor in the overall system response. Anomalies in the response of the source will appear at the output of the VTM module multiplied by its K factor. The VI Chip(R) module input/output voltage ranges must not be exceeded. An internal overvoltage lockout function prevents operation outside of the normal operating input range. Even during this condition, the powertrain is exposed to the applied voltage and power MOSFETs must withstand it. It is important to consider the impact of adding input and output capacitance to a Sine Amplitude Converter on the system as a whole. Both the capacitance value and the effective impedance of the capacitor must be considered. nn Resonant tank impedance nn Guarantee low source impedance: nn Protect the module from overvoltage transients imposed by the system that would exceed maximum ratings and cause failures: Capacitive Filtering Considerations for a Sine Amplitude ConverterTM nn Output lead inductance and internal capacitance The values of these terms are shown in the behavioral model on Page 12. It is important to note on which side of the transformer these impedances appear and how they reflect across the transformer given the K factor. The overall AC impedance varies from model to model. For most models it is dominated by DC ROUT value from DC to beyond 500kHz. The behavioral model on Page 12 should be used to approximate the AC impedance of the specific model. Any capacitors placed at the output of the VTM module reflect back to the input of the module by the square of the K factor (Equation 9) with the impedance of the module appearing in series. It is very important to keep this in mind when using a PRMTM regulator to power the VTM module. Most PRM modules have a limit on the maximum amount of capacitance that can be applied to the output. This capacitance includes both the PRM output capacitance and the VTM module output capacitance reflected back to the input. In PRM module remote-sense applications, it is important to consider the reflected value of VTM module output capacitance when designing and compensating the PRM module control loop. Capacitance placed at the input of the VTM module appear to the load reflected by the K factor with the impedance of the VTM module in series. In step-down ratios, the effective capacitance is increased by the K factor. The effective ESR of the capacitor is decreased by the square of the K factor, but the impedance of the module appears in series. Still, in most step-down VTM modules an electrolytic capacitor placed at the input of the module will have a lower effective impedance compared to an electrolytic capacitor placed at the output. This is important to consider when placing capacitors at the output of the module. Even though the capacitor may be placed at the output, the majority of the AC current will be sourced from the lower impedance, which in most cases will be the module. This should be studied carefully in any system design using a module. In most cases, it should be clear that electrolytic output capacitors are not necessary to design a stable, wellbypassed system. VTMTM Current Multiplier Page 14 of 19 Rev 3.6 07/2018 VTM48Ex120y025A00 Current Sharing Reverse Operation The SACTM topology bases its performance on efficient transfer of energy through a transformer without the need of closedloop control. For this reason, the transfer characteristic can be approximated by an ideal transformer with some resistive drop and positive temperature coefficient. The VTM48EF120T025A00 is capable of reverse operation. If a voltage is present at the output which satisfies the condition VOUT > VIN * K at the time the VC voltage is applied, or after the unit has started, then energy will be transferred from secondary to primary. The input-to-output ratio will be maintained. The VTM48EF120T025A00 will continue to operate in reverse as long as the input and output are within the specified limits. The VTM48EF120T025A00 has not been qualified for continuous operation (>10ms) in the reverse direction. This type of characteristic is close to the impedance characteristic of a DC power distribution system, both in behavior (AC dynamic) and absolute value (DC dynamic). When connected in an array with the same K factor, the VTM module will inherently share the load current (typically 5%) with parallel units according to the equivalent impedance divider that the system implements from the power source to the point-of-load. Some general recommendations to achieve matched array impedances: nn Dedicate common copper planes within the PCB to deliver and return the current to the modules. nn Provide the PCB layout as symmetric as possible. nn Apply same input / output filters (if present) to each unit. For further details see: AN:016 Using BCM(R) Bus Converters in High Power Arrays. VIN ZIN_EQ1 - ZOUT_EQ1 RO_1 ZIN_EQ2 + VTM1 VTM2 VOUT ZOUT_EQ2 RO_2 DC Load ZIN_EQn VTMn ZOUT_EQn RO_n Figure 20 -- VTM module array Fuse Selection In order to provide flexibility in configuring power systems VI Chip(R) products are not internally fused. Input line fusing of VI Chip products is recommended at system level to provide thermal protection in case of catastrophic failure. The fuse shall be selected by closely matching system requirements with the following characteristics: nn Current rating (usually greater than maximum current of VTM module) nn Maximum voltage rating (usually greater than the maximum possible input voltage) nn Ambient temperature nn Nominal melting I2t VTMTM Current Multiplier Page 15 of 19 Rev 3.6 07/2018 VTM48Ex120y025A00 J-Lead Package Mechanical Drawing mm [inch] NOTES: NOTES: mm 2. DIMENSIONS ARE mm inch . 2. DIMENSIONS ARE . inch UNLESS OTHERWISE SPECIFIED, TOLERANCES ARE: SPECIFIED, TOLERANCES ARE: 3.UNLESS .X / [.XX]OTHERWISE = +/-0.25 / [.01]; .XX / [.XXX] = +/-0.13 / [.005] 3.4..XPRODUCT / [.XX] = +/-0.25 / [.01];ON .XXTOP / [.XXX] = +/-0.13 / [.005] MARKING SURFACE 4. PRODUCT MARKING ON TOP SURFACE DXF and PDF files are available on vicorpower.com DXF and PDF files are available on vicorpower.com J-Lead Package Recommended Land Pattern mm 2. DIMENSIONS ARE mm inch . 2. DIMENSIONS ARE inchSPECIFIED, . UNLESS OTHERWISE TOLERANCES ARE: UNLESS OTHERWISE SPECIFIED, TOLERANCES ARE: VTMTM Current Multiplier Page 16 of 19 3. .X / [.XX] = +/-0.25 / [.01]; .XX / [.XXX] = +/-0.13 / [.005] 3.4..XPRODUCT / [.XX] = +/-0.25 / [.01];ON .XXTOP / [.XXX] = +/-0.13 / [.005] MARKING SURFACE 4. PRODUCT MARKING ON TOP SURFACE DXF and PDF files are available on vicorpower.com DXF and PDF files are available on vicorpower.com Rev 3.6 07/2018 VTM48Ex120y025A00 Through-Hole Package Mechanical Drawing mm [inch] NOTES: mm 2. DIMENSIONS ARE inch . UNLESS OTHERWISE SPECIFIED, TOLERANCES ARE: NOTES: 3. .X / [.XX] = +/-0.25 / [.01]; .XX / [.XXX] = +/-0.13 / [.005] 4. PRODUCT MARKING ON TOP SURFACE mm DXF and PDF files are available on vicorpower.com 2. DIMENSIONS ARE inch . UNLESS OTHERWISE SPECIFIED, TOLERANCES ARE: 3. .X / [.XX] = +/-0.25 / [.01]; .XX / [.XXX] = +/-0.13 / [.005] 4. PRODUCT MARKING ON TOP SURFACE DXF and PDF files are available on vicorpower.com Through-Hole Package Recommended Land Pattern mm 2. DIMENSIONS ARE inch . UNLESS OTHERWISE SPECIFIED, TOLERANCES ARE: mm 2. DIMENSIONS ARE inch . UNLESS OTHERWISE SPECIFIED, TOLERANCES ARE: VTMTM Current Multiplier Page 17 of 19 3. .X / [.XX] = +/-0.25 / [.01]; .XX / [.XXX] = +/-0.13 / [.005] 4. PRODUCT MARKING ON TOP SURFACE DXF and PDF files are available on vicorpower.com 3. .X / [.XX] = +/-0.25 / [.01]; .XX / [.XXX] = +/-0.13 / [.005] 4. PRODUCT MARKING ON TOP SURFACE DXF and PDF files are available on vicorpower.com Rev 3.6 07/2018 VTM48Ex120y025A00 Recommended Heat Sink Push Pin Location (NO GROUNDING CLIPS) (WITH GROUNDING CLIPS) Notes: 1. Maintain 3.50 [0.138] Dia. keep-out zone free of copper, all PCB layers. 2. (A) Minimum recommended pitch is 39.50 (1.555). This provides 7.00 [0.275] component edge-to-edge spacing, and 0.50 [0.020] clearance between Vicor heat sinks. (B) Minimum recommended pitch is 41.00 [1.614]. This provides 8.50 [0.334] component edge-to-edge spacing, and 2.00 [0.079] clearance between Vicor heat sinks. 3. VI Chip(R) module land pattern shown for reference only; actual land pattern may differ. Dimensions from edges of land pattern to push-pin holes will be the same for all full-size VI Chip(R) products. 5. Unless otherwise specified: Dimensions are mm [inches] tolerances are: x.x (x.xx) = 0.3 [0.01] x.xx (x.xxx) = 0.13 [0.005] 4. RoHS compliant per CST-0001 latest revision. 6. Plated through holes for grounding clips (33855) shown for reference, heat sink orientation and device pitch will dictate final grounding solution. VTM Module Pin Configuration 4 3 2 +OUT B B C C D D F G H H J J +OUT -OUT +IN Signal Name Pin Number +IN A1 - E1, A2 - E2 -IN L1 - T1, L2 - T2 TM H1, H2 VC J1, J2 PC K1, K2 +OUT A3 - D3, A4 - D4, J3 - M3, J4 - M4 -OUT E3 - H3, E4 - H4, N3 - T3, N4 - T4 E E -OUT 1 A A K K L L M M N N P P R R TM VC PC -IN T T Bottom View VTMTM Current Multiplier Page 18 of 19 Rev 3.6 07/2018 VTM48Ex120y025A00 Vicor's comprehensive line of power solutions includes high density AC-DC and DC-DC modules and accessory components, fully configurable AC-DC and DC-DC power supplies, and complete custom power systems. Information furnished by Vicor is believed to be accurate and reliable. However, no responsibility is assumed by Vicor for its use. Vicor makes no representations or warranties with respect to the accuracy or completeness of the contents of this publication. Vicor reserves the right to make changes to any products, specifications, and product descriptions at any time without notice. Information published by Vicor has been checked and is believed to be accurate at the time it was printed; however, Vicor assumes no responsibility for inaccuracies. Testing and other quality controls are used to the extent Vicor deems necessary to support Vicor's product warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. Specifications are subject to change without notice. Visit http://www.vicorpower.com/dc-dc-converters-board-mount/vtm for the latest product information. Vicor's Standard Terms and Conditions and Product Warranty All sales are subject to Vicor's Standard Terms and Conditions of Sale, and Product Warranty which are available on Vicor's webpage (http://www.vicorpower.com/termsconditionswarranty) or upon request. Life Support Policy VICOR'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL COUNSEL OF VICOR CORPORATION. As used herein, life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user. 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The products described on this data sheet are protected by the following U.S. Patents Numbers: 5,945,130; 6,403,009; 6,710,257; 6,911,848; 6,930,893; 6,934,166; 6,940,013; 6,969,909; 7,038,917; 7,145,186; 7,166,898; 7,187,263; 7,202,646; 7,361,844; D496,906; D505,114; D506,438; D509,472; and for use under 6,975,098 and 6,984,965. Contact Us: http://www.vicorpower.com/contact-us Vicor Corporation 25 Frontage Road Andover, MA, USA 01810 Tel: 800-735-6200 Fax: 978-475-6715 www.vicorpower.com email Customer Service: custserv@vicorpower.com Technical Support: apps@vicorpower.com (c)2018 Vicor Corporation. All rights reserved. The Vicor name is a registered trademark of Vicor Corporation. All other trademarks, product names, logos and brands are property of their respective owners. VTMTM Current Multiplier Page 19 of 19 Rev 3.6 07/2018