NQ16W50XMA16

Technical S pecification NQ16W50xMA16 6.0-16.0V Input 0.75-5.0V Outputs 16 Amp Current Non Isolated SIP Single Inline Pins Th e N iQo r ® S M T D C / D C c o n v e r t e r i s a n o n - i s o l a t e d b u c k re gu la tor, wh ich e mplo ys synchro no us recti ficat ion to ach i ev e ext rem ely h i gh c onv ers ion eff i ci enc y. T h e N iQor fa m ily o f c on v e rt e rs are us ed p re d om i n at e ly i n D PA sys t em s usi ng a front end DC /DC high p ower br ick (48 Vin to low vo l ta ge bu s) . Th e n o n -i so la te d Ni Qo r c on v e rt e rs a re t h e n used a t t he poi n t of load t o crea t e t h e low v olt a ge out p ut s requ ired by t h e desi gn . T he wi de t ri m m odu le ca n b e pro gram m ed t o a v ari et y of ou t pu t v olt a ges t hr ough t he u se of a single external resistor. RoHS compliant (see page 12 ). Operational Features • Ultra high efficiency, up to 94% at full rated load • Delivers up to 16 Amps of output current with minimal derating - no heatsink required • Input Voltage Range : 6.0 - 16.0V • Fast transient response time • On-board input and output filter capacitor • No minimum load requirement means no preload resistors required Non-Isolated NiQor wide trim module Pr otection Features • Input under-voltage lockout disables converter at low input voltage conditions • Temperature compensated over-current shutdown protects converter from excessive load current or short circuits • Output over-voltage protection protects load from damaging voltages • Thermal shutdown protects converter from abnormal environmental conditions Mechanical Features • DOSA standard pin-out configuration • Industry standard size: 2” x 0.5” x 0.288” (50.8 x 12.7 x 7.32 mm) • Total weight: 0.3 oz. (9.4 grams), lower mass greatly reduces vibration and shock problems • Open frame construction maximizes air flow cooling • Also available in SIP packaging Safety Features • UL/cUL 60950-1 recognized (US & Canada) • TUV certified to EN60950-1 • Meets 72/23/EEC and 93/68/EEC directives which facilitates CE Marking in user’s end product • Board and plastic components meet UL94V-0 flammability requirements Contr ol Features • On/Off control • Output voltage trim (industry standard) permits custom voltages and voltage margining • Remote Sense (standard option) Product # NQ16W50xMA16 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2NV12WE Rev. B 11/26/07 Page 1 Technical Specification MECHANICAL DIAGRAM Front View 2.00 (50.8) Input: Outputs: Current: Package: 6.0 - 16.0V 0.75 - 5.0V 16A SIP Vertical Mount Side View 0.288 (7.32) 0.185 (4.7) 0.315 Max (8.0 Max) 0.197 Max (5.0 Max) 0.500 (12.70) 0.050 Ref. 1 2 3 4 5 A 6 7 8 9 10 11 0.160 (4.06) (1.27) 0.050 (1.27) 0.040 PCB Ref. (1.02) 0.120 (3.05) 0.025 + 0.003 (0.64 + 0.076) 0.000 (0.00) 0.100 (2.54) 0.200 (5.08) 0.300 (7.62) 0.400 (10.16) 1.300 (33.02) 1.400 1.500 1.600 1.700 1.800 (35.56) (38.10) (40.64) (43.18) (45.72) 1.900 (48.26) SQ. Typ. NOTES 1) All pins are 0.025” (0.64mm) +0.003 (0.076mm) square. 2) All Pins: Material - Copper Alloy Finish - Tin over Nickel plate 3) Vertical, horizontal, vertical with reverse pins and surface mount options (future) available. 4) Undimensioned components are shown for visual reference only. 6) All dimensions in inches (mm) Tolerances: x.xx +0.02 in. (x.x +0.5mm) x.xxx +0.010 in. (x.xx +0.25mm) 7) Weight: 0.30 oz. (9.4 g) typical 8) Workmanship: Meets or exceeds IPC-A-610C Class II PIN DESIGNATIONS Pin No. Name Function 1 2 3 4 5 A 6 7 8 9 10 11 Vout(+) Vout(+) SENSE(+) Vout(+) Common N/C Common Vin(+) Vin(+) N/C TRIM1 ON/OFF2 Positive output voltage Positive output voltage Positive remote sense Positive output voltage No Connection Positive input voltage Positive input voltage No Connection Output voltage trim (trim-up only) LOGIC input to turn the converter on and off. Pin Connection Notes: 1. Pin 10 - for fixed resistors, connect between Trim and Common (Ground). 2. Pin 11 - see section on Remote ON/OFF pin for description of enable logic options. Pins in Italics Shaded text are Optional Product # NQ16W50xMA16 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2NV12WE Rev. B 11/26/07 Page 2 Technical Specification MECHANICAL DIAGRAM Front View 2.00 (50.8) Input: Outputs: Current: Package: 6.0 - 16.0V 0.75 - 5.0V 16A SIP Horizontal Mount Side View 0.288 (7.32) 0.185 (4.7) 0.315 Max (8.0 Max) 0.197 Max (5.0 Max) 0.500 (12.70) 0.025 + 0.003 (0.64 + 0.076) 0.050 Ref. (1.27) SQ. Typ. 1 2 3 4 5 A 6 7 8 9 10 11 0.050 (1.27) 0.128 Min (3.25 Min) 0.040 PCB Ref. (1.02) 0.330 (8.38) 0.000 (0.00) 0.100 (2.54) 0.200 (5.08) 0.300 (7.62) 0.400 (10.16) 1.300 (33.02) 1.400 1.500 1.600 1.700 1.800 (35.56) (38.10) (40.64) (43.18) (45.72) 1.900 (48.26) See previous page for notes and pin designations. Product # NQ16W50xMA16 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2NV12WE Rev. B 11/26/07 Page 3 Technical Specification Input: Outputs: Current: Package: 6.0 - 16.0V 0.75 - 5.0V 16A SIP TA=25°C, airflow rate=300 LFM, Vin=12Vdc unless otherwise noted; full operating temperature range is -40°C to +105°C ambient temperature with appropriate power derating. Specifications subject to change without notice. ELECTRICAL CHARACTERISTICS - NQ16W50xMA16 Series Parameter Module All All All All All All All All All All All All All 0.75V 2.5V 5.0V 0.75V 2.5V 5.0V All All All 0.75V 2.5V 5.0V 0.75V All All All All All All 1.0V 2.5V 5.0V All All All All All All All All All 0.75V 2.5V 5.0V 0.75V 2.5V 5.0V 2 2 77.0 90.0 94.0 81.0 91.5 94.0 Min. 0 -40 -55 -3 6 100 0.75 0 5.35 4.50 Typ. Max. 18 16 105 125 15 16 20 5.5 16 Units V V °C °C V V A µF V A V V V A A A mA mA mA mA A 2s µF mA mA mA V V A % % % % mV mV mV A µF dB mV mV µs Notes & Conditions Continuous Continuous ABSOLUTE MAXIMUM RATINGS Input Voltage Non-Operating Operating Operating Temperature Storage Temperature Voltage at ON/OFF input pin RECOMMENDED OPERATING CONDITIONS Input Voltage Range Input Fuse Rating External Input Capacitance Output Voltage Output Current INPUT CHARACTERISTICS Input Under-Voltage Lockout Turn-On Voltage Threshold Turn-Off Voltage Threshold Lockout Hysteresis Maximum Input Current “ “ No-Load Input Current “ “ Disabled Input Current Inrush Current Transient Rating Input Filter Capacitor Value Input Reflected-Ripple Current “ “ OUTPUT CHARACTERISTICS Output Voltage Set Point Output Voltage Range Operating Output Current Range Output Voltage Regulation Over Line Over Load Over Temperature Total Output Voltage Range Output Voltage Ripple and Noise (pk-pk\RMS) “ “ Output DC Over Current Shutdown External Output Capacitance DYNAMIC CHARACTERISTICS Input Voltage Ripple Rejection Output Voltage during Current Transient For a Step Change in Output Current (0.1A/µs) For a Step Change in Output Current (3A/µs) Settling Time Turn on Transient Inhibit Time Rise Time Output Voltage Overshoot EFFICIENCY 100% Load “ “ 50% Load “ “ Fast blow external fuse recommended ESR0.5mW 120Hz 50%-75%-50% Iout max; 100uF 50%-75%-50% Iout max; 470uF To within 1.5% Vout nom. Resistive load “ “ 17 0 28 5000 ms ms V % % % % % % Product # NQ16W50xMA16 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2NV12WE Rev. B 11/26/07 Page 4 Technical Specification Parameter Module All All All All All All All All All All All All All All All All All 275 1.5 -3.0 20 -0.2 2.2 Vin 20 0.75 5.6 6.0 128 10 15.6 10.0 5.5 6.4 1.0 Vin 300 Input: Outputs: Current: Package: 6.0 - 16.0V 0.75 - 5.0V 16A SIP ELECTRICAL CHARACTERISTICS (continued) - NQ16W50xMA16 Series Min. Typ. Max. 125 125 325 6.5 0.6 Units °C °C kHz V V kW Notes & Conditions Package rated to 150°C UL rated max operating temp 130°C Half on small duty cycle (e.g. 16Vin; 0.75Vout) See Figure A TEMP LIMITS FOR POWER DERATING Semiconductor Junction Temperature Board Temperature FEATURE CHARACTERISTICS Switching Frequency ON/OFF Control Open Logic (O) ON/OFF Control Off-State Voltage On-State Voltage Input Resistance Positive Logic (P) ON/OFF Control Logic Low Voltage Range Logic High Voltage Range (internal pullup) Pull-up Voltage Pull-up Resistance Output Voltage Trim Range Output Over-Voltage Protection Over-Temperature Shutdown Over-Temperature Shutdown Restart Hysteresis RELIABILITY CHARACTERISTICS Calculated MTBF (Telcordia) Calculated MTBF (MIL-217) Field Demonstrated MTBF Open collector/drain input; see Figure A V V V kW V V °C °C Measured Vout+ to common pins Over full temp range Average PCB Temperature 106 Hrs. TR-NWT-000332; 100% load, 200LFM, 40oC Ta 106 Hrs. MIL-HDBK-217F; 100% load, 200LFM, 40oC Ta 106 Hrs. See our website for details STANDARDS COMPLIANCE Parameter P STANDARDS COMPLIANCE Notes File # E194341 Certified by TUV Test on entire assembly; board & plastic components UL94V-0 compliant ESD test, 8kV - NP, 15kV air - NP (Normal Performance) Section 7 - electrical safety, Section 9 - bonding/grounding UL/cUL 60950-1 EN60950-1 72/23/EEC 93/68/EEC Needle Flame Test (IEC 695-2-2) IEC 61000-4-2 GR-1089-CORE Telcordia (Bellcore) GR-513 • An external input fuse must always be used to meet these safety requirements. Contact SynQor for official safety certificates on new releases or download from the SynQor website. QUALIFICATION TESTING Parameter P QUALIFICATION TESTING # Units 32 5 5 10 5 5 5 15 pins Test Conditions 10-55Hz sweep, 0.060” total excursion,1 min./sweep, 120 sweeps for 3 axis Life Test Vibration Mechanical Shock Temperature Cycling Power/Thermal Cycling Design Marginality Humidity Solderability 95% rated Vin and load, units at derating point, 1000 hours 100g minimum, 2 drops in x and y axis, 1 drop in z axis -40°C to 100°C, unit temp. ramp 15°C/min., 500 cycles Toperating = min to max, Vin = min to max, full load, 100 cycles Tmin-10°C to Tmax+10°C, 5°C steps, Vin = min to max, 0-105% load 85°C, 85% RH, 1000 hours, continuous Vin applied except 5min./day MIL-STD-883, method 2003 • Extensive characterization testing of all SynQor products and manufacturing processes is performed to ensure that we supply robust, reliable product. Contact the factory for official product family qualification documents. OPTIONS SynQor provides various options for Packaging, Enable Logic, and Feature Set for this family of DC/DC converters. Please consult the last page for information on available options. PATENTS SynQor is protected under various patents. Please consult the last page for further details. Product # NQ16W50xMA16 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2NV12WE Rev. B 11/26/07 Page 5 Technical Specification 100 95 4 90 5 Input: Outputs: Current: Package: 6.0 - 16.0V 0.75 - 5.0V 16A SIP Efficiency (%) 85 80 75 70 65 60 0 2 4 6 8 10 12 14 16 Power Dissipation (W) 3 2 5.0 Vout 1.8 Vout 0.9 Vout 1 5.0 Vout 1.8 Vout 0.9 Vout 0 0 2 4 6 8 10 12 14 16 Load Current (A) Load Current (A) Figure 1: Efficiency at nominal output voltage vs. load current for nominal input voltage at 25°C. Figure 2: Power dissipation at nominal output voltage vs. load current for nominal input voltage at 25°C. 18 16 14 12 Iout (A) 10 8 6 4 2 0 0 25 40 55 70 85 400 LFM (2.0 m/s) 300 LFM (1.5 m/s) 200 LFM (1.0 m/s) 100 LFM (0.5 m/s) Semiconductor junction temperature is within 1°C of surface temperature Ambient Air Temperature (°C) Figure 3: Maximum output power derating curves for 0.75Vo, 1.2Vo, 1.5Vo units under various thermal conditions and nominal input voltage. 18 16 14 12 Figure 4: Thermal plot of 0.75Vo, 1.2Vo converters at nominal Vin and 16 amp load current mounted on a 85°C, 6-Layer, 2 oz. copper board (typical installation). Iout (A) 10 8 6 4 2 0 0 25 40 55 70 85 400 LFM (2.0 m/s) 300 LFM (1.5 m/s) 200 LFM (1.0 m/s) 100 LFM (0.5 m/s) Semiconductor junction temperature is within 1°C of surface temperature Ambient Air Temperature (°C) Figure 5: Maximum output power derating curves for 1.8Vo, 2.5Vo units under various thermal conditions and nominal input voltage. Product # NQ16W50xMA16 Phone 1-888-567-9596 Figure 6: Thermal plot of 1.8Vo, 2.5Vo converters at nominal Vin and 16 amp load current mounted on a 70°C, 6-Layer, 2 oz. copper board (typical installation). Doc.# 005-2NV12WE Rev. B 11/26/07 Page 6 www.synqor.com Technical Specification 18 16 14 12 Input: Outputs: Current: Package: 6.0 - 16.0V 0.75 - 5.0V 16A SIP Iout (A) 10 8 6 4 2 0 0 25 40 55 70 85 400 LFM (2.0 m/s) 300 LFM (1.5 m/s) 200 LFM (1.0 m/s) 100 LFM (0.5 m/s) Semiconductor junction temperature is within 1°C of surface temperature Ambient Air Temperature (°C) Figure 7: Maximum output power derating curves for 3.3Vo, 5.0Vo units under various thermal conditions and nominal input voltage. Figure 8: Thermal plot of 3.3Vo, 5.0Vo converters at nominal Vin and 16 amp load current mounted on a 70°C, 6-Layer, 2 oz. copper board (typical installation). 5.0Vout 5.0Vout 3.3Vout 3.3Vout 1.8Vout 0.9Vout 1.8Vout 0.9Vout on/off on/off Figure 9: Turn-on transient at full load (resistive load) (2 ms/div). Ch 1: ON/OFF input (5V/div) Ch 2-4: Vout (1V/div) Figure 10: Turn-on transient at zero load (2 ms/div). Ch 1: ON/OFF input (5V/div) Ch 2-4: Vout (1V/div) 5.0Vout 5.0Vout 1.8Vout 1.8Vout 0.9Vout 0.9Vout Iout Iout Figure 11: Output voltage response for 0.9V, 1.8V, 5V units to step-change in load current (50-75-50% of Iout max; di/dt=0.1A/µ s). Load cap: 100µ F, 100mW ESR tant, 10µ F cer. Ch 1: Iout (10A/div), Ch 2-4: Vout (100mV/div). Product # NQ16W50xMA16 Phone 1-888-567-9596 Figure 12: Output voltage response for 0.9V, 1.8V, 5V units to step-change in load current (50-75-50% of Iout max; di/dt=3A/µ s). Load cap: 470µ F, 100mW ESR tant, 10µ F cer. Ch 1: Iout (10A/div), Ch 2-4: Vout (100mV/div). Doc.# 005-2NV12WE Rev. B 11/26/07 Page 7 www.synqor.com Technical Specification See Fig. 14 source impedance Input: Outputs: Current: Package: 6.0 - 16.0V 0.75 - 5.0V 16A SIP 1 µH 0.9Vout See Fig. 15 See Fig. 16 1.8Vout iS VSOURCE VIN DC/DC Converter VOUT 3.3Vout C* ceramic capacitor 22 µF 5.0Vout * See values for recommended external input capacitance. Inductor optional as needed. Figure 13: Test set-up diagram showing measurement points for Input Reflected Ripple Current (Figure 14), Input Terminal Ripple Voltage (Figure 15), and Output Voltage Ripple (Figure 16). Figure 14: Input Reflected Ripple Current, is, through a 1 µ H source inductor at nominal input voltage and rated load current (100 mA/div). See Figure 13. 0.9Vout 0.9Vout 1.8Vout 1.8Vout 3.3Vout 3.3Vout 5.0Vout 5.0Vout Figure 15: Input Terminal Ripple Voltage at nominal input voltage and rated load current (200 mV/div). Load capacitance: 22µ F ceramic cap. Bandwidth: 20 MHz. See Figure 13. 1 Figure 16: Output Voltage Ripple at nominal input voltage and rated load current (50 mV/div). Load capacitance: 22µ F ceramic cap. Bandwidth: 20 MHz. See Figure 13. 0 -10 Forward Transmission (dB) Output Impedance (ohms) -20 -30 -40 -50 -60 -70 -80 -90 -100 5.0 Vout 1.8 Vout 0.9 Vout 1,000 10,000 100,000 1,000,000 0.1 0.01 0.001 5.0 Vout 1.8 Vout 0.9 Vout 0.0001 10 100 1,000 10,000 100,000 100 Hz Hz Figure 17: Magnitude of incremental output impedance (Zout = vout/iout) for nominal input voltage at full rated power. Product # NQ16W50xMA16 Phone 1-888-567-9596 Figure 18: Magnitude of incremental forward transmission (FT = vout/vin) for nominal input voltage at full rated power. Doc.# 005-2NV12WE Rev. B 11/26/07 Page 8 www.synqor.com Technical Specification 15 100 Input: Outputs: Current: Package: 6.0 - 16.0V 0.75 - 5.0V 16A SIP Reverse Transmission (dB) 5 10 -5 Input Impedance (ohms) 1 -15 0.1 -25 5.0 Vout -35 1.8 Vout 0.9 Vout -45 10 100 1,000 10,000 100,000 1,000,000 0.01 5.0 Vout 1.8 Vout 0.9 Vout 0.0001 10 100 1,000 10,000 100,000 0.001 Hz Hz Figure 19: Magnitude of incremental reverse transmission (RT = iin/iout) for nominal input voltage at full rated power. Figure 20: Magnitude of incremental input impedance (Zin = vin/iin) for nominal input voltage at full rated power. Product # NQ16W50xMA16 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2NV12WE Rev. B 11/26/07 Page 9 Technical Specification BASIC OPERATION AND FEATURES The NiQor series non-isolated converter uses a buck-converter that keeps the output voltage constant over variations in line, load, and temperature. The NiQor modules employ synchronous rectification for very high efficiency. Dissipation throughout the converter is so low that it does not require a heatsink or metal baseplate for operation. The NiQor converter can thus be built more simply and reliably using high yield surface mount techniques on a single PCB substrate. The NiQor series of SIPs and SMT converters uses the established industry standard footprint and pin-out configurations. Input: Outputs: Current: Package: 6.0 - 16.0V 0.75 - 5.0V 16A SIP For a desired increase of the nominal output voltage, the value of the resistor should be: Rtrim-up = 10500 VDES - 0.7525 or _ 1000 (W) VOUT = 0.7525 + 10500 Rtrim-up + 1000 (W) where VDES = Desired Output Voltage CONTROL FEATURES REMOTE ON/OFF: The ON/OFF input permits the user to control when the converter is on or off. There are currently two options available for the ON/OFF input described in the table below. Others may become available if demand exists. Pin-Open Float Voltage 5 0 Pin-Open Converter State On On To maintain the accuracy of the output voltage over load current, it is vital that any trim-up resistor be terminated directly to the converter's ground foot, not at the connection to the load. A separate Kelvin connection to the PCB pad for the ground foot is optimal. Trim-down resistors should be terminated at the converter's Sense+ pin. We do not recommend bypassing the trim pin directly to ground with a capacitor. The voltage gain from the trim pin to output is rather large, 15:1. Ground bounce through a bypass capacitor could introduce significant noise to the converter's control circuit. Option P Logic O Logic Description Positive/Open Negative/Open Pin Action Pull Low = Off Pull High = Off PROTECTION FEATURES Input Under-Voltage Lockout: The converter is designed to turn off when the input voltage is too low, helping avoid an input system instability problem, described in more detail in the application note titled “Input System Instability”. The lockout circuitry is a comparator with DC hysteresis. When the input voltage is rising, it must exceed the typical Turn-On Voltage Threshold value (listed on the specification page) before the converter will turn on. Once the converter is on, the input voltage must fall below the typical Turn-Off Voltage Threshold value before the converter will turn off. Output Current Limiting: To provide protection in an output over load fault condition, the unit is equipped with internal overcurrent protection. When the over-current protection is triggered, the unit enters hiccup mode. The units operate normally once the fault condition is removed. OUTPUT VOLTAGE TRIM: The TRIM input permits the user to adjust the output voltage according to the trim range specifications by using an external resistor. If the TRIM feature is not being used, leave the TRIM pin disconnected. TRIM-UP: To increase the output voltage from the nominal setpoint of 0.7525V using an external resistor, connect the resistor Rtrim-up between the TRIM and the Ground pin according to the diagram below. Vout Sense+ Vin On/Off Gnd Trim Rtrim-up Internal Over-Voltage Protection: To fully protect from excessive output voltage, the NQ16 series contains an Output Over-Voltage Shutdown circuitry. This OVP is independent of the trimmed setpoint. As such, the converter's load is protected from faults in the external trim circuitry (such as a trim pin shorted to ground). Since the setpoint of this OVP does not track trim, it is set at 6.0V, in the wide-trim W50 model. Product # NQ16W50xMA16 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2NV12WE Rev. B 11/26/07 Page 10 Technical Specification The shutdown point is fixed on standard option. These converters also offer adjustable OVP set point. For more detailed information contact SynQor technical support. Over-Temperature Shutdown: A temperature sensor on the converter senses the average temperature of the module. The thermal shutdown circuit is designed to turn the converter off when the temperature at the sensed location reaches the OverTemperature Shutdown value. It will allow the converter to turn on again when the temperature of the sensed location falls by the amount of the Over-Temperature Shutdown Restart Hysteresis value. Input: Outputs: Current: Package: 6.0 - 16.0V 0.75 - 5.0V 16A SIP tance is recommended when operating with more than 1000uF of output capacitance on lower voltage outputs when trimming down by more than half of the trim-down allowance (e.g., further than -2.5% on a 0.9V, or -5% on a 1.2V). Input inductance should be reduced for maintaining input stability when operating with large output capacitance (>1000µF). Reducing input inductance to 1000µF), an input capacitance equal to or greater than the output capacitance may be needed to compensate the input impedance. If no inductor is used to isolate the input ripple of the NiQor converters from the source or from inputs of other NiQor converters, then this external capacitance might be provided by the DC/DC converter used as the power source. SynQor's PowerQor series converters typically have tantalum and ceramic output capacitors that would provide the damping. An input inductor would help isolate the ripple currents and voltages from the source or other NiQor style converters on the voltage supply rail. If an input inductor is used, the recommended capacitance should guarantee stability and control the ripple current for up to 1.0µH of input inductance. The input inductor need not have very high inductance. A value of 250 nanohenries would equate to almost 500 miliohm of series impedance at the switching frequency of 300 kHz. This would be working against an assumed capacitive ESR of 30mW on the supply side of the inductor, providing significant isolation and ripple reduction. No external capacitance is required at the output, however, the ripple voltage can be further reduced if ceramic and tantalum capacitors are added at the output. Since the internal output capacitance is about 50µF, approximately that amount of ceramic capacitance would be needed to produce a noticeable reduction in output ripple. The value of the tantalum capacitors is both to provide a high capacitance for pulsed loads and to provide damping of the distribution network with their inherent ESR, which is low, but higher than ceramics. Additional output capacitance in the range of 300-500µF is beneficial for reducing the deviation in response to a fast load transient. Input Over-Voltage Prevention: The power system designer must take precautions to prevent damaging the NiQor converters by input overvoltage. This is another reason to be careful about damping the input filter so that no ringing occurs from an underdamped filter. The voltage must be prevented from exceeding the absolute maximum voltage indicated in the Electrical Doc.# 005-2NV12WE Rev. B 11/26/07 Page 11 APPLICATION CONSIDERATIONS Input and Output Filtering: SynQor recommends an external input capacitor of either a tantalum, polymer or aluminum electrolytic type on the input of the NQ16 series non-isolated converters. This capacitance and resistance primarily provides damping of the input filter, reduces the source impedance and guarantees input stability (see SynQor application note "Input System Instability"). The input filter is formed by any source or wiring inductance and the converter’s input capacitance. The external capacitance also provides an additional benefit of ripple voltage reduction. A modest sized capacitor would suffice in most conditions, such as a 330µF, 16V tantalum, with an ESR of approximately 50 mW. The NiQor family converters have an internal ceramic input capacitor to reduce ripple current stress on the external capacitors. An external ceramic capacitor of similar size (330µF) with a series resistor of approximately 50 mW would also suffice and would provide the filter damping. Additional ceramic capacitance may be needed on the input, in parallel with the tantalum capacitor, to relieve ripple current stress on the tantalum capacitors. The external capacitance forms a current divider with the 40µF internal ceramic capacitance. At 300 kHz., the impedance of the internal capacitance is about 15mW capacitive. At that frequency, an SMT 330µF tantalum capacitor would have an impedance of about 50mW resistive, essentially just the ESR. In this example, at full load, that would stress the tantalum input capacitor to about 3A rms ripple current, possibly beyond its rating. Placing an additional 40µF of ceramic in parallel with that capacitor would reduce the ripple current to about 1.5A, probably within its rating at 85oC. The input ripple current is proportional to load current, so this example should be scaled down according to the actual load current. Additional input capacitance equal to half of the output capaciProduct # NQ16W50xMA16 Phone 1-888-567-9596 www.synqor.com Technical Specification Specifications section of the data sheet under all conditions of turn-on, turn-off and load transients and fault conditions. The power source should have an over voltage shutdown threshold as close as reasonably possible to the operating point. Additional protection can come from additional input capacitance, perhaps on the order of 1,000µF, but contingent on the source inductance value. A large source inductance would require more capacitance to keep the input voltage below the absolute maximum, if the load current were interrupted suddenly. This can be caused by either a shutdown of the NiQor from a fault or from the load itself, for example when a card is hotswapped out, suddenly dropping the load to zero. This is further justification for keeping the source inductance low, as mentioned above. When the power source is configured with remote sensing, the series resistance of the filter inductor and any other conductors or devices between the source and the sense point will result in a voltage drop which, in the event of a load current interruption, would add to the NiQor input voltage. A TVS device could also be used to clamp the voltage level during these conditions, but the relatively narrow range between operating voltage and the absolute maximum voltage restrict the use of these devices to lower source current levels that will not drive the transient voltage suppressor above the voltage limit when all the source current is flowing into the clamp. A TVS would be a good supplemental control, in addition to careful selection of inductance and capacitance values. Equivalent Model for Input Ripple: A simple but reasonably accurate model of input ripple is to treat the NiQor input as a pulsed AC current source at 300 kHz.in parallel with a very low ESR capacitor, see Figure E. The peak-to-peak current of the source model is equal to the NiQor load current, representing the peak current in the NiQor's smoothing choke. The capacitor represents the 40µF input ceramic capacitance of the NiQor converter, with a nearly negligible ESR of less than 1 mW. A further refinement can be made by setting the duty cycle of the pulsed source to the output voltage divided by the input voltage. The only error in this simplified model is that it ignores the ripple current in the choke, usually less than 20% of the load current, and it ignores the resistive losses inside the NiQor converter, which would alter the duty cycle very slightly. The model is a good guide for calculating the effects of external input capacitors and other filter elements on ripple voltage and ripple current stress on capacitors. Input: Outputs: Current: Package: 6.0 - 16.0V 0.75 - 5.0V 16A SIP 30µF INPUT I p-p I p-p = I Load