14. Input Attenuator Module (IAM / MI-IAM) Design Guide & Applications Manual For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies OVERVIEW EMC The IAM is a component-level, DC input front-end filter that when used in conjunction with the Vx-200 and Vx-J00 Family of DC-DC converters provides a highly efficient, high density power system with outputs from 1 – 95 Vdc and power expansion from 25 – 800 W. EMC performance is guaranteed when the IAM is used in conjunction with the recommended Vicor converters within the permissible power rating and in accordance with the recommended installation procedure. (Figure14–3) The capacitor shown across the input of the converter and bypass capacitors shown on the –IN and +IN of the DC-DC converters to ground are required to meet EMC specifications. The capacitors should be Y-rated (interference suppression). Y capacitors have high voltage breakdown ratings to meet the isolation characteristics of the module’s input to baseplate specification, self-healing properties, and safety agency approvals. There are five input attenuator modules available for the commercial market that comply with telecommunication and industrial control EMC specifications: Refer to data sheets for applicable standards at vicorpower.com. Input Voltage Range VI-A11-xU 24 V (21 – 32 V) VI-AWW-xU 24 V “W” (18 – 36 V) VI-A33-xQ 48 V (42 – 60 V) VI-ANN-xQ 48 V “N” (36 – 76 V) VI-A66-xQ 300 V (200 – 400 V) Model [a] Maximum Output Power[a] of Converter Combinations 200 W 200 W 400 W 400 W 400 W INPUT REVERSE POLARITY PROTECTION A Zener diode in the EMC filter provides reverse polarity protection when used with a properly rated fuse external to the IAM. The characteristics of the recommended input line fuses permit normal full load operation with protection in the event of a reverse polarity by clearing of the fuse. (Table 4–3). Based on DC-DC converters with 5 V outputs or higher. Table 14 –1 — Output power capability There are two input attenuator modules available for the defense market that comply with military EMC specifications, transient specifications and spike specifications. Refer to product data sheet for applicable standards at vicorpower.com. Model MI-A22-xU MI-A66-xU Input Voltage Range 28 V (16 – 50 V) 270 V (125 – 400 V) INPUT TRANSIENT PROTECTION A Zener diode, inductor and capacitor in the EMC filter protect against short term transients. Transient voltages that persist beyond these limits are dropped across an N-channel enhancement FET, Q1. It is necessary that the FET be kept in saturation mode during normal operation. Thus it is necessary to connect the DC-DC converters’ GATE OUT to the IAM’s GATE OUT to charge pump the Maximum Output Power of Converter Combinations 200 W 200 W Table 14 –2 — Output power capability +OUT +IN Q1 +IN D1 C2 Vref 1 EMI Filter OV U2 Vref 2 OC –IN D2 Level Shift GATE OUT 10V PARALLEL GATE IN Q2 U1 –OUT –IN Figure 14–1 — Block diagram of Input Attenuator Module (IAM) VI-200 and VI-J00 Family Design Guide Page 43 of 98 Rev 3.5 Apps. Eng. 800 927.9474 vicorpower.com 800 735.6200 14. Input Attenuator Module (IAM / MI-IAM) Design Guide & Applications Manual For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies INPUT CURRENT gate of the FET to a voltage in excess of its source. In the case where multiple DC-DC Driver modules are connected to one IAM, an external charge pump through the PARALLEL pin (connected to the gate of the FET) must be added to ensure that the FET remains enhanced in the event GATE OUT enhancement is lost (Figure 14 – 4). The additional circuitry, C2, D1 and D2 are added externally to charge pump through the PARALLEL pin. Shut down of the DC-DC converters is accomplished by saturating Q2 during an input overvoltage to prevent possible damage to the converters. The IAM will automatically restart when the input overvoltage is reduced to within the input voltage range. If the long term transient withstand specifications are exceeded, the recommended external fuse will clear. Input Voltage Recommended Fuse 24 V 24 V “W” 48 V 48 V “N” 300 V 28 V 270 V 20 A / 32 V (AGC-20) 20 A / 36 V (AGC-20) 20 A / 60 V (3AB-20) 20 A / 80 V (3AB-20) 5 A / 250 V Bussman PC-Tron 20 A / 250 V (3AB-20 or F03A, 125 V, 20 A) 5 A / 250 V Bussman PC-Tron or F03A, 250 V, 4 A Inrush current is a function of the number of DC-DC converters that are connected to the input attenuator module (modules are not gated off at turn-on) and the amount of external capacitance added between the Input Attenuator Module and the DC-DC converter. The inrush current specification is 125% of steady state input current for 10 ms. To avoid excessive dissipation in the element controlling the inrush (Q1), the following maximum values of external capacitance must be adhered to. Input Voltage Maximum Capacitance[a] 24 Vdc (21 – 32 V) 24 Vdc (18 – 36 V) 28 Vdc (18 – 50 V) 48 Vdc (42 – 60 V) 48 Vdc (36 – 76 V) 270 Vdc (125 – 400 V) 300 Vdc (200 – 400 V) [a] 470 µF 470 µF 390 µF 220 µF 120 µF 27 µF 27 µF Capacitance should be distributed across the input of each DC-DC converter. (C1, Figure 14–3) Table 14 –4 — Recommended distributed capacitance on input of DC-DC converter(s) Table 14 –3 — Recommended fusing based on input voltage 48 V Input Wide Range R.E. 100V 100V R.E. 160V I.S.W. Full Load S.D. 100V 36V 32V 1 10ms Normal Operating Area 42V 0.1 18V 1000 100 48 V Wide Range Input 276V 125V 1 10ms 1000 R.E. 800V 500V 100V S.D. 100 I.S.W. Full Load S.D. 400V 76V Normal Operating Area 36V 0.1 1 10ms 100 Normal Operating Area S.D. 1000 600 500 400 200V 0.1 500ms 1 10ms 100 1000 500ms I.S.W.: Input surge withstand (no disruption of performance) R.E.: Ratings exceeded S.D.: Shut down 28 Vdc Input Ratings Exceeded 300 200 100 OVP 0 -100 -200 -400 -500 -600 10-6 10-5 10-4 10-3 1ms TIME (SECONDS) 270 Vdc Input Page 44 of 98 Rev 3.5 Apps. Eng. 800 927.9474 10-2 10ms 100 1s 10-1 100ms Ratings Exceeded 800 600 400 OVP 200 0 200 500 400 Reverse Polarity 400 600 10-6 10-5 10-4 vicorpower.com 800 735.6200 10-3 1ms TIME (SECONDS) Figure 14–2 — Safe operating area based on input voltage of IAM VI-200 and VI-J00 Family Design Guide 50V Reverse Polarity -300 300 V Input R.E. I.S.W. Full Load S.D. 60V Normal Operating Area 21V 0.1 I.S.W. Full Load VOLTS-PEAK VALUE OF SPIKE VOLTAGE 24 V Inputs Standard VOLTS-PEAK VALUE OF SPIKE VOLTAGE Safe Operating Area (1% duty cycle max., Zs = 0.5Ω, for short duration transient capability refer to specifications) 10-2 10ms 10-1 100ms 100 1s 14. Input Attenuator Module (IAM / MI-IAM) Design Guide & Applications Manual For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies OUTPUT OVERCURRENT / SHORT CIRCUIT PROTECTION the Input Attenuator Modules to ensure equal potential at these points when paralleling Input Attenuator Modules, so as not to impact the effectiveness of the internal common-mode choke. Output overcurrent protection is a foldback type, followed by a timed latched shut down should the overcurrent persist beyond 2 ms. If the overcurrent condition is removed before the timeout interval, auto restart shall occur. Should latched shut down occur, input power must be recycled to restart. Output Overcurrent Threshold 24 Vin “W”, 28 Vin, 48 Vin “N” 24 Vin, 48 Vin 270 Vin, 300 Vin 4,700 pF 20 A 15 A 4A Table 14–5 — IAM overcurrent To IAM EXPANSION CAPABILITIES The Input Attenuator Module incorporates a PARALLEL pin permitting power expansion as long as the total output power from the DC-DC converters does not exceed the power rating of each Input Attenuator Module (EMC specifications are guaranteed for up to two input attenuators in parallel). It is necessary to include a 100 Ω, 1/4 W resistor between the negative outputs of + – +IN +OUT +IN –IN GATE IN PAR GATE OUT –IN –OUT +IN GATE IN GATE OUT –IN +IN GATE IN GATE OUT –IN D3 D1, D2, D3: 1N4148 C2: 470 pF/500V D2 C2 +IN GATE IN GATE OUT –IN D3 D1 [a] For bus voltages greater than 75 V, a 1N4006 diode should be used for the diodes (D3) connected to the GATE IN pins. D2 C2 +OUT Driver +S Trim –S –Out +OUT Driver +S TRIM –S –OUT +OUT Driver +S TRIM –S –OUT NOTE: x,y capacitors not shown for clarity Figure 14–4 — IAM multiple Driver interconnection VI-200 and VI-J00 Family Design Guide Page 45 of 98 +OUT +S TRIM –S –OUT Figure 14–3 — External x,y capacitors for EMC requirements D3 D1 Driver/ Booster Connection to module baseplate or ground plane connected to baseplate 4,700 pF IAM [a] C1 +IN GATE IN GATE OUT –IN Rev 3.5 Apps. Eng. 800 927.9474 vicorpower.com 800 735.6200 14. Input Attenuator Module (IAM / MI-IAM) Design Guide & Applications Manual For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies SAFETY CONSIDERATIONS Shock Hazard. Agency compliance requires that the baseplate be grounded or made inaccessible. +IN +IN + – –IN –IN Fusing. Safety agency conditions of acceptability require module input fusing. See Table 14–3 for recommended fuse ratings. +OUT GATE IN PAR GATE OUT –OUT IAM [a] Diodes: 1N4148 C2: 470 pf / 500 V C2 +IN GATE IN GATE OUT –IN VI-200 Driver +IN GATE IN GATE OUT –IN VI-200 Booster +OUT +S TRIM –S –OUT +OUT +S TRIM –S –OUT +IN GATE IN GATE OUT – IN VI-200 Driver +IN GATE IN GATE OUT –IN VI-200 Booster +IN GATE IN GATE OUT – IN VI-200 Driver +OUT +S TRIM –S –OUT 100Ω +IN +OUT +IN GATE IN PAR GATE OUT –OUT –IN –IN IAM C2 [a] For bus voltages greater than 75 V, a 1N4006 diode should be used for the diodes connected to the GATE IN pins. +OUT +S TRIM –S –OUT +OUT +S TRIM –S –OUT NOTE: x,y capacitors not shown for clarity Figure 14–5 — Paralleling connections for the IAM VI-200 and VI-J00 Family Design Guide Page 46 of 98 Rev 3.5 Apps. Eng. 800 927.9474 vicorpower.com 800 735.6200