Technical Specification Quarter Brick 24Vin 1.8Vout 25A 25 Amp, No Heatsink, Isolated DC/DC Converter The PQ24018QGA25 PowerQor™ Giga quarterbrick converter is a next-generation, board-mountable, isolated, fixed switching frequency dc/dc converter that uses synchronous rectification to achieve extremely high conversion efficiency. The power dissipated by the converter is so low that a heatsink is not required, which saves cost, weight, height, and application effort. All of the power and control components are mounted to the multi-layer PCB substrate with high-yield surface mount technology. Since the PowerQor converter has no explicit thermal connections, it is extremely reliable. PQ24018QGA25 Module Operational Features • High efficiency, >84% at full rated load current • Delivers up to 25 amps of output current with minimal derating - no heatsink required • Wide input voltage range: 18V – 36V meets or exceeds all 24V bus standards • Fixed frequency switching provides predictable EMI performance • No minimum load requirement means no preload resistors required Mechanical Features • Industry standard quarter-brick pin-out configuration • Industry standard size: 1.45” x 2.3” • Total height less than 0.40”, permits better airflow and smaller card pitch • Total weight: 34 grams (1.2 oz.), lower mass greatly reduces vibration and shock problems Control Features • On/Off control referenced to input side (positive and negative logic options are available) • Remote sense for the output voltage compensates for output distribution drops • Output voltage trim permits custom voltages and voltage margining Product # PQ24018QGA25 Phone 1-888-567-9596 Protection Features • Input under-voltage lockout disables converter at low input voltage conditions • Output current limit and short circuit protection 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 Safety Features • 2000V, 10 MΩ input-to-output isolation provides input/output ground separation • UL 1950 recognized (US & Canada), basic insulation rating (pending) • TUV certification to EN60950 (pending) • Meets 72/23/EEC and 93/68/EEC directives which facilitates CE Marking in user’s end product • Board and plastic components meet 94V-0 flammability requirements • NEBS and ETSI compliant Doc.# 005-2QG218D_A 3/1/02 Page 1 Technical Specification Quarter Brick 24Vin 1.8Vout 25A 2.30 (58.4) 0.14 (3.6) 2.00 (50.8) 0.300 0.150 (7.62) (3.81) 0.43 (10.9) 1.45 (36.8) 0.450 Top View 0.600 (15.24) (11.43) 0.600 (15.24) 0.300 (7.62) 0.145 (3.68) See Note 3 0.40 (10.2) Shown Actual Size Side View 1) Pins 1-3, 5-7 are 0.040” (1.02mm) dia. with 0.080” (2.03mm) dia. standoff shoulders. 2) Pins 4 and 8 are 0.062” (1.57 mm) dia. with 0.100” (2.54mm) dia. standoff shoulders. 3) Other pin extension lengths available. 4) Undimensioned components are for visual reference only. 5) Weight: 1.2 oz. (34g) typical 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) Workmanship: Meets or exceeds IPC-A-610B Class II Pin No. Name Function 1 Vin(+) Positive input voltage (18 - 36V) 2 ON/OFF TTL input to turn converter on and off, referenced to Vin(-), with internal pull up. 3 Vin(-) Negative input voltage 4 Vout(-) Negative output voltage 5 SENSE(-) Negative remote sense1 6 TRIM Output voltage trim2 ABSOLUTE MAXIMUM RATINGS 7 SENSE(+) Positive remote sense3 Input Voltage: Non-Operating: 72V continuous Operating: 60V continuous Input/Output Isolation Voltage: 2000V Storage Temperature: -55°C to +125°C Operating Temperature: -40°C to +115°C Voltage at ON/OFF input pin: +18V / -2V 8 Vout(+) Positive output voltage Notes: 1. Pin 5 should be connected to Vout(-) at load. 2. Leave Pin 6 open for nominal output voltage. 3. Pin 7 should be connected to Vout(+) at load. OPTIONS SAFETY • Logic sense - Negative (N); converter is on when the ON/OFF signal is low. Positive (P); converter is on when the ON/OFF signal is high. Logic input is TTL compatible with an internal pull up. Use N or P as 13th letter in part number to indicate logic. • Pin Length - a variety of pin lengths are available for all modules (see last page). The14th letter in the part number indicates pin length. • Feature Set - Quarter-bricks are available with Standard (S) feature options only. Use S as 15th letter in part number to indicate feature set. • UL 1950 - All modules are UL 1950 recognized (US & Canada) with basic insulation rating. • EN60950 - All modules are TUV certified to EN60950 requirements. • 72/23/EEC - All modules meet 72/23/EEC directives. • 93/68/EEC - All modules meet 93/68/EEC directives. • 94V-0 - All modules meet 94V-0 flammability requirements for board and plastic components. • NEBS - All modules meet NEBS compatibility. • An external input fuse must always be used to meet these safety requirements. Product # PQ24018QGA25 Phone 1-888-567-9596 Doc.# 005-2QG218D_A 3/1/02 Page 2 Technical Specification Quarter Brick 24Vin 1.8Vout 25A PQ24018QGA25 ELECTRICAL CHARACTERISTICS TA=25°C, airflow rate=300 LFM, Vin=24Vdc, nominal Vout unless otherwise noted; full operating temperature range is -40°C to +115°C ambient temperature with appropriate power derating. Specifications subject to change without notice. PARAMETER NOTES and CONDITIONS INPUT CHARACTERISTICS Operating Input Voltage Range Input Under-Voltage Lockout Turn-On Voltage Threshold Turn-Off Voltage Threshold Lockout Hysteresis Voltage Maximum Input Current No-Load Input Current Off Converter Input Current Input Reflected-Ripple Current 100% Load, 18Vin Typ. Max. Units 18 24 36 V 15.5 14.0 1.0 16.0 14.5 1.5 16.5 15.0 2.0 3.0 100 3 V V V A mA mA mA 60 1.6 6 P-P thru 3.3µH inductor; Figures 13 & 15 OUTPUT CHARACTERISTICS Output Voltage Set Point Output Voltage Regulation Over Line Over Load Over Temperature Total Output Voltage Range Output Voltage Ripple and Noise Peak-to-Peak RMS Operating Output Current Range Output DC Current-Limit Inception Short-Circuit Protection (redundant shutdown) DYNAMIC CHARACTERISTICS Input Voltage Ripple Rejection Output Voltage Current Transient Positive Step Change in Output Current Negative Step Change in Output Current Settling Time to within 1% Vout nominal Turn-On Transient Turn-On Time Start-Up Inhibit Period Maximum Output Capacitance 1.782 over sample line, load and temperature 20MHz bandwidth; Figures 13 & 16 Full Load, 1µF ceramic, 10µF tantalum Full Load, 1µF ceramic, 10µF tantalum Output Voltage 10% Low; Fig. 17 & 18 1.75 0 26 52 120 Hz; Figure 20 470µF load cap, 5A/µs; Figure 12 50% Io to 75% Io 75% Io to 50% Io Full load, Vout=90% nom.; Figs 9 & 10 -40°C to +125°C; Figure F Full load; 5% overshoot of Vout at startup EFFICIENCY 100% Load 50% Load 1 180 Figure 1 TEMPERATURE LIMITS FOR POWER DERATING CURVES Semiconductor Junction Temperature Board Temperature Transformer Temperature 1.800 1.816 V +0.1 (2) +0.1 (2) +9 +0.3 (5) +0.3 (5) +27 1.85 % (mV) % (mV) mV V 25 6 50 12 25 34 60 mV mV A A A 30 56 TBD dB 190 190 700 mV mV µs 4 200 Isolation Voltage Isolation Resistance Isolation Capacitance 220 See circuit diagram; Figure B Pull up to Vin/3 Across Pins 8 & 4; Figures C & D Over full temp range; % of nominal Vout Average PCB Temperature °C °C °C V MΩ pF 470 260 kHz -2 2.4 0.8 18 V V 2.4 -2 18 0.8 V V 9.6 V kΩ % % °C -20 117 240 ms ms µF % % 125 125 125 2000 10 FEATURE CHARACTERISTICS 8 215 35,000 84 87 Plastic Package rated to 150°C Board rated to 165°C Figures 5 - 8 ISOLATION CHARACTERISTICS Switching Frequency ON/OFF Control (Option P) Off-State Voltage On-State Voltage ON/OFF Control (Option N) Off-State Voltage On-State Voltage ON/OFF Control (Either Option) Pull-Up Voltage Pull-Up Resistance Output Voltage Trim Range Output Over-Voltage Protection Over-Temperature Shutdown PQ24018QGA25 Min. Vin/3 33 122 125 +10 127 Patents: SynQor is protected under various patents, including but not limited to U.S. Patent # 5,999,417. Product # PQ24018QGA25 Phone 1-888-567-9596 Doc.# 005-2QG218D_A 3/1/02 Page 3 Performance Curves Quarter 24Vin 1.8Vout 25A Brick 88 90 87 85 86 Efficiency (%) Efficiency (%) 95 80 75 70 3 5 8 10 13 15 18 20 23 83 25 C 40 C 55 C 81 80 60 0 84 82 18Vin 24Vin 36Vin 65 85 0 25 100 200 Figure 1: Efficiency at nominal output voltage vs. load current for minimum, nominal, and maximum input voltage at 25°C. 400 12 6.0 10 5.5 8 6 4 18Vin 2 24Vin 5.0 4.5 4.0 25 C 40 C 3.5 36Vin 0 0 3 5 8 10 13 15 500 Figure 2: Efficiency at nominal output voltage and 60% rated power vs. airflow rate for ambient air temperatures of 25°C, 40°C, and 55°C (nominal input voltage). Power Dissipation (W) Power Dissipation (W) 300 Air Flow (LFM) Load Current (A) 18 20 23 25 Load Current (A) 55 C 3.0 0 100 200 300 400 500 Air Flow (LFM) Figure 3: Power dissipation at nominal output voltage vs. load current for minimum, nominal, and maximum input voltage at 25°C. Figure 4: Power dissipation at nominal output voltage and 60% rated power vs. airflow rate for ambient air temperatures of 25°C, 40°C, and 55°C (nominal input voltage). 25 Iout (A) 20 15 10 400 LFM (2.0 m/s) 300 LFM (1.5 m/s) 200 LFM (1.0 m/s) 5 100 LFM (0.5 m/s) 0 LFM (0 m/s) 0 0 Vin = 24V 25 40 55 70 85 Ambient Air Temperature (oC) Figure 5: Maximum output power derating curves vs. ambient air temperature for airflow rates of 0 LFM through 400 LFM with air flowing across the converter from pin 1 to pin 3 (nominal input voltage). Product # PQ24018QGA25 Phone 1-888-567-9596 Semiconductor junction temperature is within 1°C of surface temperature Figure 6: Thermal plot of converter at 25 amp load current with 55°C air flowing at the rate of 200 LFM. Air is flowing across the converter sideways from pin 1 to pin 3 (nominal input voltage). Doc.# 005-2QG218D_A 3/1/02 Page 4 Performance Curves Quarter Brick 24Vin 1.8Vout 25A 25 Iout (A) 20 15 10 400 LFM (2.0 m/s) 300 LFM (1.5 m/s) 200 LFM (1.0 m/s) 5 100 LFM (0.5 m/s) 0 LFM (0 m/s) 0 0 Vin = 24V 25 40 55 70 85 o Ambient Air Temperature ( C) Semiconductor junction temperature is within 1°C of surface temperature Figure 7: Maximum output power derating curves vs. ambient air temperature for airflow rates of 0 LFM through 400 LFM with air flowing lengthwise from output to input (nominal input voltage). Figure 8: Thermal plot of converter at 25 amp load current with 55°C air flowing at the rate of 200 LFM. Air is flowing across the converter from output to input (nominal input voltage). Figure 9: Turn-on transient at full load (resistive load) (2 ms/div). Ch1: Vout (500mV/div) Ch2: ON/OFF input (5V/div) Figure 10: Turn-on transient at zero load (2 ms/div). Ch1: Vout (500mV/div) Ch2: ON/OFF input (5V/div) Figure 11: Output voltage response to step-change in load current (50%-75%-50% of Iout(max); dI/dt = 0.1A/µs). Load cap: 10µF, 100 mΩ ESR tantalum capacitor and 1µF ceramic capacitor. Ch1: Vout (100mV/div), Ch2: Iout (10A/div). Product # PQ24018QGA25 Phone 1-888-567-9596 Figure 12: Output voltage response to step-change in load current (50%-75%-50% of Iout(max): dI/dt = 5A/µs). Load cap: 470µF, 30 mΩ ESR tantalum capacitor and 1µF ceramic capacitor. Ch1: Vout (100mV/div), Ch2: Iout (10A/div). Doc.# 005-2QG218D_A 3/1/02 Page 5 Performance Curves Quarter Brick Figure 15 3.3 µH Figure 14 source impedance Figure 16 iS VSOURCE 24Vin 1.8Vout 25A iC DC/DC Converter VOUT 1 µF 100 µF, ≅0.33Ω ESR 10 µF, ceramic 100mΩ ESR capacitor tantalum capacitor electrolytic capacitor Figure 13: Test set-up diagram showing measurement points for Input Terminal Ripple Current (Figure 14), Input Reflected Ripple Current (Figure 15) and Output Voltage Ripple (Figure 16). Figure 14: Input Terminal Ripple Current, ic, at full rated output current and nominal input voltage with 3.3µH source impedance and 100µF electrolytic capacitor (500 mA/div). See Figure 13. Figure 15: Input reflected ripple current, is, through a 3.3 µH source inductor at nominal input voltage and rated load current (10 mA/div). See Figure 13. Figure 16: Output voltage ripple at nominal input voltage and rated load current (20 mV/div). Load capacitance: 1µF ceramic capacitor and 10µF tantalum capacitor. Bandwidth: 20 MHz. See Figure 13. 2.0 Output Voltage (V) 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 18V 1.0 24 V 0.9 36 V 0.8 0 5 10 15 20 25 30 35 Load Current (A) Figure 17: Output voltage vs. load current showing typical current limit curves. Below 0.9V (typical), the converter will shut off, and restart after a start-up inhibit period has elapsed. (see Figure F) Product # PQ24018QGA25 Phone 1-888-567-9596 Figure 18: Load current (20A/div) as a function of time when the converter attempts to turn on into a 10 mΩ short circuit. Top trace (2.5ms/div) is an expansion of the on-time portion of the bottom trace. Doc.# 005-2QG218D_A 3/1/02 Page 6 Performance Curves Quarter 24Vin 1.8Vout 25A Brick 1 0 0.1 18 Vin 24 Vin 36 Vin 0.01 Forward Transmission (dB) Output Impedance (Ω ) -10 -20 -30 18 Vin 24 Vin -40 36 Vin -50 -60 -70 0.001 10 100 1,000 10,000 10 100,000 100 1,000 10,000 100,000 Hz Hz Figure 19: Magnitude of incremental output impedance (Zout = vout/iout) for minimum, nominal, and maximum input voltage at full rated power. Figure 20: Magnitude of incremental forward transmission (FT = vout/vin) for minimum, nominal, and maximum input voltage at full rated power. 0 100 -20 18 Vin 24 Vin 36 Vin -30 -40 Input Impedance (Ω ) Reverse Transmission (dB) -10 10 18 Vin 24 Vin 36 Vin 1 -50 -60 0.1 10 100 1,000 10,000 100,000 10 100 Hz 10,000 100,000 Hz Figure 21: Magnitude of incremental reverse transmission (RT = iin/iout) for minimum, nominal, and maximum input voltage at full rated power. Product # PQ24018QGA25 1,000 Phone 1-888-567-9596 Figure 22: Magnitude of incremental input impedance (Zin = vin/iin) for minimum, nominal, and maximum input voltage at full rated power. Doc.# 005-2QG218D_A 3/1/02 Page 7 Technical Specification Quarter Brick BASIC OPERATION AND FEATURES The PowerQor series converter uses a two-stage power circuit topology. The first stage is a buck-converter that keeps the output voltage constant over variations in line, load, and temperature. The second stage uses a transformer to provide the functions of input/output isolation and voltage stepdown to achieve the low output voltage required. Both the first stage and the second stage switch at a fixed frequency for predictable EMI performance. Rectification of the transformer’s output is accomplished with synchronous rectifiers. These devices, which are MOSFETs with a very low on-state resistance, dissipate far less energy than Schottky diodes used in conventional dc/dc converters. This is the primary reason that the PowerQor converter has such high efficiency—even at very low output voltages and very high output currents. Dissipation throughout the converter is so low that the PowerQor converter requires no heatsink to deliver a greater level of power than can be delivered by a conventional, Schottky-diode-based dc/dc converter with a 0.5” high heatsink. At equivalent ambient air temperature, airflow rate, and output power level, the hottest semiconductor junction temperature and the hottest PCB temperature within the PowerQor converter are cooler than those found in conventional dc/dc converters with a 0.5” high heatsink attached. Since a heatsink is not required, the PowerQor converter does not need a metal baseplate or potting material to help conduct the dissipated energy to the heatsink. The PowerQor converter can thus be built more simply using high yield surface mount techniques on a PCB substrate. Unlike conventional dc/dc converters, which have critical thermal connections between the power components and the baseplate, and between the baseplate and the heatsink, the PowerQor converter has no explicit, failure-prone thermal connections. Compared to a conventional Schottky-diode-based dc/dc converter with a 0.5” high heatsink, the PowerQor converter is more efficient and therefore it dissipates less than half the energy. Additionally, because the PowerQor converter is thinner (0.4” vs. 1.0”), the board-to-board pitch in a rack can be much smaller, and cooling airflow is less impeded by Product # PQ24018QGA25 Phone 1-888-567-9596 24Vin 1.8Vout 25A the converter. Because the PowerQor converter is much lighter, vibration and shock-induced problems are greatly reduced. Moreover, due to the lack of failure-prone explicit thermal connections and the lack of potting material the PowerQor converter is more reliable than conventional dc/dc converters. The PowerQor series converter uses the industry standard pin-out configuration used by other vendors of comparably sized and rated dc/dc converters. The unit is pin for pin compatible with the Lucent QW series. The PowerQor converter has many standard control and protection features. All shutdown features are non-latching, meaning that the converter shuts off for 200ms before restarting. (see Figure F) • An ON/OFF input permits the user to control when the converter is on and off in order to properly sequence different power supplies and to reduce power consumption during a standby condition. • Remote sense inputs permit the user to maintain an accurate voltage at the load despite distribution voltage drops between the converter’s output and the load. • An output voltage trim input permits the user to trim the output voltage up or down to achieve a custom voltage level or to do voltage margining. • An input under-voltage lockout avoids input system instability problems while the input voltage is rising. • The output current limit protects both the converter and the board on which it is mounted against a short circuit condition. (see Figure 18) • An output over-voltage limit circuit shuts the unit down if the output voltage at the output pins gets too high. • A sensor located in a central spot of the PCB provides a PCB temperature limit. If, due to an abnormal condition, this spot gets too hot, the converter will turn off. Once the converter has cooled, it will automatically turn on again without the need to recycle the input power. CONTROL PIN DESCRIPTIONS Pin 2 (ON/OFF): The ON/OFF input, Pin 2, permits the user to control when the converter is on or off. This input is Doc.# 005-2QG218D_A 3/1/02 Page 8 Technical Specification Quarter 24Vin 1.8Vout 25A Brick referenced to the return terminal of the 24V input bus. There are two versions of the PowerQor series converter that differ by the sense of the logic used for the ON/OFF input. In the PQxxyyyQGAzzPxx version, the ON/OFF input is active high (meaning that a high turns the converter on). In the PQxxyyyQGAzzNxx version, the ON/OFF signal is active low (meaning that a low turns the converter on). Figure A details five possible circuits for driving the ON/OFF pin. Figure B shows detail of the internal ON/OFF circuitry. voltage across the output (pins 8 and 4) to determine when it should trigger, not the voltage across the converter’s sense pins (pins 7 and 5). Therefore, the resistive drop on the board should be small enough so that output OVP does not trigger, even during load transients. Pin 6 (TRIM): The TRIM input permits the user to adjust the output voltage across the sense leads up or down. To lower the output voltage, the user should connect a resistor between Pin 6 and Pin 5, which is the SENSE(-) input. To raise the output voltage, the user should connect a resistor between Pin 6 and Pin 7, which is the SENSE(+) input. Pins 7 and 5 (SENSE(+)): The SENSE(+) inputs correct for voltage drops along the conductors that connect the converter’s output pins to the load. A resistor connected between Pin 6 and Pin 5 will decrease the output voltage. For a desired decrease of ∆ percent of the nominal output voltage, the value of this resistor should be Pin 7 should be connected to Vout(+) and Pin 5 should be connected to Vout(-) at the point on the board where regulation is desired. That is, [Vout(+) - Vout(-)] – [SENSE(+) - SENSE (-)] < 10%Vout Remote Enable Circuit and ON/OFF VNOM – VDES VNOM 5V Vin(+) Positive Logic 100k (Permanently Enabled) 50k ON/OFF TTL TTL/ CMOS ON/OFF 50k Vin(_) Vin(_) Open Collector Enable Circuit Direct Logic Drive Figure A: Various circuits for driving the ON/OFF pin. Product # PQ24018QGA25 x 100% VNOM = Nominal Voltage VDES = Desired Voltage Vin(_) 5V ON/OFF ) (kΩ) ON/OFF Vin(_) Negative Logic (Permanently Enabled) ( ∆= Note: the output over-voltage protection circuit senses the Vin(_) (511 ∆% ) - 10.22 where Pins 7 and 5 must be connected for proper regulation of the output voltage. However, if these connections are not made, nothing catastrophic will happen to the converter under normal operating conditions—the converter will simply deliver an output voltage that is slightly higher than its specified value. ON/OFF Rtrim-down = Phone 1-888-567-9596 100pF Vin(_) Figure B: Internal ON/OFF pin circuitry (detail) Doc.# 005-2QG218D_A 3/1/02 Page 9 Technical Specification Quarter Brick Figure C graphs this relationship between Rtrim-down and ∆. The output voltage can be trimmed down as much as 20%. Trim Resistance (kOhms) 10,000 24Vin 1.8Vout 25A Note: The TRIM feature does not affect the voltage at which the output over-voltage protection circuit is triggered. Trimming the output voltage too high may cause the overvoltage protection circuit to trip, particularly during transients. TOTAL DC VARIATION OF Vout: For the converter to meet its full specifications, the maximum variation of the dc value of Vout, due to both trimming and remote load voltage drops, should not be greater than +10%/-20% 1,000 100 PROTECTION FEATURES 10 0 2 4 6 8 10 12 14 16 18 20 % Decrease in Output Voltage Figure C: Trim Down Graph for 1.8Vout A resistor connected between Pin 6 and Pin 7 will increase the output voltage. For a desired increase of ∆ percent of the nominal output voltage, the value of this resistor should be Rtrim-up = ( 5.11VOUT(100+∆%) _ 511 _ 10.22 1.225∆% ∆% ) (kΩ) where VOUT = Nominal Output Voltage Figure D graphs this relationship between Rtrim-up and ∆. The output voltage can be trimmed up as much as 10%. Output Current Limit: The current limit does not change appreciably as the output voltage drops. However, once the impedance of the short across the output is small enough to make the output voltage drop below approximately 60% of its nominal value, the converter turns off. The converter then enters a mode where it repeatedly turns on and off at a 5 Hz (nominal) frequency with a 5% duty cycle until the short circuit condition is removed. This prevents excessive heating of the converter or the load board. Output Over-Voltage Limit: If the voltage across the output pins exceeds the O.V. threshold, the converter will immediately stop switching. This prevents damage to the load circuit due to 1) a sudden unloading of the converter, 2) a release of a short-circuit condition, or 3) a release of a current limit condition. Load capacitance determines exactly how high the output voltage will rise in response to these conditions. After 200 ms the converter will automatically restart. 10,000 Trim Resistance (kOhms) 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 below. The lockout circuitry is a comparator with dc hysteresis. When the input voltage is rising, it must exceed a typical value of 16V before the converter will turn on. Once the converter is on, the input voltage must fall below a typical value of 14.5V before the converter will turn off. 1,000 100 10 0 1 2 3 4 5 6 7 8 9 10 % Increase in Output Voltage Figure D: Trim Up Graph for 1.8Vout Product # PQ24018QGA25 Phone 1-888-567-9596 Thermal Shutdown: The PowerQor series has a temperature sensor located such that it senses the average temperature of the converter. The thermal shutdown circuit is designed to turn the converter off when the temperature at the sensed location reaches 125°C. It will allow the conDoc.# 005-2QG218D_A 3/1/02 Page 10 Technical Specification Quarter 24Vin 1.8Vout 25A Brick verter to turn on again when the temperature of the sensed location falls below 115°C. APPLICATION CONSIDERATIONS Input System Instability: This condition can occur because a dc/dc converter appears incrementally as a negative resistance load. A detailed application note titled “Input System Instability” is available on the SynQor web site (www.synqor.com) which provides an understanding of why this instability arises, and shows the preferred solution for correcting it. Application Circuits: Figure E below provides a typical circuit diagram which is useful when using input filtering and voltage trimming. Input Filtering 3.3µH Electrolytic Capacitor 100µF ESR ≅0.33Ω Vin(+ ) Vout(+ ) Vsense(+ ) ON/OFF 18V < Vin < 36V Vin(_) Trim Vsense(_) Vout(_) Rtrim-up or Rtrim-down Cload Iload Figure E: Typical application circuit (negative logic unit, permanently enabled). Product # PQ24018QGA25 Phone 1-888-567-9596 Doc.# 005-2QG218D_A 3/1/02 Page 11 Technical Specification Quarter Brick STARTUP INHIBIT PERIOD The Startup Inhibit Period ensures that the converter will remain off for at least 200ms when it is shut down for any reason. When an output short is present, this generates a 5Hz "hiccup mode," which prevents the converter from overheating. In all, there are seven ways that the converter can be shut down, initiating a Startup Inhibit Period: • Input Under-Voltage Lockout • Input Over-Voltage Shutdown (not present in Quarterbrick) 24Vin 1.8Vout 25A Figure F shows three turn-on scenarios, where a Startup Inhibit Period is initiated at t0, t1, and t2: Before time t0, when the input voltage is below 16V (typ.), the unit is disabled by the Input Under-Voltage Lockout feature. When the input voltage rises above 16V, the Input Under-Voltage Lockout is released, and a Startup Inhibit Period is initiated. At the end of this delay, the ON/OFF pin is evaluated, and since it is active, the unit turns on. At time t1, the unit is disabled by the ON/OFF pin, and it cannot be enabled again until the Startup Inhibit Period has elapsed. • Output Over-Voltage Protection • Over Temperature Shutdown When the ON/OFF pin goes high after t2, the Startup Inhibit Period has elapsed, and the output turns on within the 4ms (typ.) "Turn On Time." • Current Limit • Short Circuit Protection • Turned off by the ON/OFF input Vin Under-Voltage Lockout Turn-On Threshold ON/OFF (pos logic) ON OFF ON OFF ON Vout 4ms (typical turn on time) 200ms (typical start-up inhibit period) t0 200ms 200ms t1 t t2 Figure F: Startup Inhibit Period (turn-on time not to scale) Product # PQ24018QGA25 Phone 1-888-567-9596 Doc.# 005-2QG218D_A 3/1/02 Page 12 Technical Specification Quarter 24Vin 1.8Vout 25A Brick PART NUMBERING SYSTEM ORDERING INFORMATION The part numbering system for SynQor’s PowerQor DC/DC converters follows the format shown in the example below. The tables below show the valid model numbers and ordering options for converters in this product family. When ordering SynQor converters, please ensure that you use the complete 15 character part number consisting of the 12 character base part number and the additional 3 characters for options. PQ 48 033 H T A 50 N K S Options (see Ordering Information) Output Current Thermal Design Performance Level Package Size Output Voltage Input Voltage Product Family Model Number Input Voltage PQ24018QGA25xyz PQ24033QGA25xyz PQ24050QGA20xyz PQ24120QGA08xyz PQ24150QGA07xyz 18 - 36 V 18 - 36 V 18 - 36 V 18 - 36 V 18 - 36 V Output Max Output Full Load Voltage Current Efficiency 1.8 V 25 A 84% 3.3 V 25 A 87% 5.0 V 20 A 87% 12 V 8.3 A 88% 15 V 6.7 A 87% The following option choices must be included in place of the x y z spaces in the model numbers listed above. The first 12 characters comprise the base part number and the last 3 characters indicate available options. Although there are no default values for enable logic and pin length, the most common options are negative logic and 0.145” pins. These part numbers are more likely to be readily available in stock for evaluation and prototype quantities. Options Description: x y z Enable Logic Pin Length Feature Set K - 0.110" P - Positive N - 0.145" S - Standard N - Negative R - 0.180" Y - 0.250" Application Notes Available • Current Sharing for Full Feature Modules • EMI Characteristics • Thermal Relief Vias • Input System Instability All application notes and technical white papers can be downloaded in pdf format at www.synqor.com. Contact SynQor for further information: Phone: Toll Free: Fax: E-mail: Web: Address: Product # PQ24018QGA25 978-567-9596 888-567-9596 978-567-9599 [email protected] www.synqor.com 188 Central Street Hudson, MA 01749 Phone 1-888-567-9596 Warranty SynQor offers a three (3) year limited warranty. Complete warranty information is listed on our web site or is available upon request from SynQor. Information furnished by SynQor is believed to be accurate and reliable. However, no responsibility is assumed by SynQor for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of SynQor. Doc.# 005-2QG218D_A 3/1/02 Page 13