Use of Graphs............................ 8 18.6 Thermal Models ..........................8 18.7 Detailed Thermal Model........................9 18.8 Radiation Heat Transfer........................9 18.9 Horizontal Orientation ........................9 19.0 Fusing Considerations..........................9 20.0 General Features ..........................10 21.0 Applications ............................10 KFD 6-25-28W/ 060801...
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Trim Up to Increase Voltage Setpoint ......................... 17 Heat Sinks for Vertical Orientation - Kepco Model KFD-02 and the Kepco Model KFD-04 ....18 Heat sinks for Horizontal Orientation - Kepco Model KFD-01 and the Kepco Model KFD-03....19 Forced Convection Derating, Power Dissipation Versus Local Ambient Temperature ......20 Heat Sink Derating Curves, Natural Convection, Fins Oriented Along the Width ........
2.0 DESCRIPTION: The Kepco KFD 150 Watt DC to DC Converter has a nominal 18-36 Vdc input and a 5 Volt DC output nom- inal voltage. The DC to DC Converter is a low-dissipative stabilizer, using pulse-width modulation to control the output.
5.0 OUTPUT SPECIFICATIONS (SEE TABLES 2, 3, AND 4) TABLE 2. OUTPUT SPECIFICATIONS FOR THE KFD UNIT Parameter Description Output Voltage Nominal Output Current Nominal Output Power Maximum 150W Ripple 50mV RMS max. Noise, 5Hz to 20Mhz 100 mV p-p max. Output Current Minimum 1.0A Output Current Maximum...
TABLE 4. OUTPUT SPECIFICATIONS Specification Parameter UNIT Output Voltage (Over All Operating Input Voltage, 4.75 6.25 Resistive Load, And Temperature Conditions) Output Voltage Setpoint (V =48 volts, I max, T A =25°C. Unit Operating In Parallel Or Parallel Pin Shorted To Sense (-) Pin (See Figure 3) Parallel Pin Open 6.25...
7.0 FEATURE SPECIFICATIONS (SEE TABLES 6 AND 7) TABLE 6. REMOTE ON/OFF Specification State Unit ON/.OFF CURRENT Logic Low ON/OFF VOLTAGE Logic Low Logic High I ON/OFF =0 Open Collector Switch Specifications Leakage Current During Logic High µΑ (V ON/OFF =18V) Output Low Voltage During Logic Low I ON/OFF =1mA Turn On Time (I o =80%I omax.
A jumper across the ON/OFF terminal and the -V terminal can be used to override the Remote ON/OFF (see Figure 4). Either a user-supplied switch or the override jumper should be wired into the circuit via indi- vidual PWB current paths not common to the -V current path.
15.0 REMOTE SENSE Remote Sense pins are provided to minimize the effects of distribution losses that come about from regu- lating the output voltage at the remote sense terminals. The KFD output voltage specifications refer to measurements taken at the Remote Sense terminals during parallel operation, or with the parallel pin shorted to the Sense (-) pin.
18.0 THERMAL CONSIDERATIONS To ensure reliable operation of the KFD unit, thermal management is important. Heat dissipated by the unit is conducted to the case, and subsequently convected to the surrounding air. Convection cooling can be improved by mounting a heat sink to the top of the unit. Six threaded holes, No. 4-40 [0.18 inches deep (46mm)] are provided for this purpose.
(case temperature)=95°C for the KFD c,max 150W D.C. to D.C. Converter (the KFD 6-25-28W) without a heat sink, consider the following: The KFD DC to DC Converter (150W) operates at Io=30 Amps and T =50° without a heat sink. The power dissipated by the unit can be determined from the difference between the input power and output power and the efficiency of the converter.
using a one half inch fin heat sink oriented along the length. Consider the following: For an air flow of 150 ft./min. using the same D.C. to D.C. Converter as in the last example and with a 0.5 inch heat sink with fins oriented along the length, refer to the thermal resistance plot. From Figure 14 the thermal resistance is 1.3°C/W.
data for additional data. 20.0 GENERAL FEATURES Among the general features of the KFD D.C. to D.C. Converter are the ones listed below: • Low Profile: 0.5 inch • Internal EMI Filter • Complete Input And Output Filtering • Input To Output Isolation •...
NOTE: WHEN PLACING THE POWER MODULE INTO A PRINTED CIRCUIT BOARD SOCKET, USE KELVIN CONNECTIONS AT THE POWER MODULE INPUT AND OUTPUT TERMINALS TO AVOID MEASUREMENT ERRORS DUE TO SOCKET CONTACT RESISTANCE. FIGURE 1 TEST SETUP FOR OUTPUT VOLTAGE AND EFFICIENCY MEASUREMENTS FOR THE DC TO DC CONVERTER KFD 6-25-28/060801...
NOTE: AT THE INPUT THE REFLECTED RIPPLE IS MEASURED WITH A SIMU- LATED SOURCE IMPEDANCE OF 12µH; THE CAPACITOR, C , OFFSETS POSSIBLE BATTERY IMPEDANCE. CURRENT IS MEASURED AT THE INPUT OF THE POWER MODULE. FIGURE 2 TEST SETUP FOR THE INPUT REFLECTED RIPPLE FOR THE SINGLE OUTPUT KFD DC TO DC CONVERTER.
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FIGURE 3 MECHANICAL OUTLINE DRAWING OF THE SINGLE OUT- PUT KFD DC TO DC CONVERTER KFD 6-25-28/060801...
FIGURE 6 CIRCUIT CONFIGURATION FOR SINGLE KFD DC TO DC CONVERTER REMOTE SENSE OPERATION KFD 62528W/060801...
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FIGURE 7 (TOP) KFD DC TO DC CONVERTER CIRCUIT CONFIGURA- TION FOR R , TO DECREASE VOLTAGE SETPOINT Trim Down FIGURE 8 (BOTTOM) KFD DC TO DC CONVERTER CIRCUIT CONFIG- URATION FOR R , TO INCREASE VOLTAGE SETPOINT Trim Up KFD 6-25-28/060801...
NOTE: THE GRAPHS ARE PLOTTED AS A FUNCTION OF THE AIR FLOW WITHOUT THE USE OF A HEAT SINK (FOR THE KFD POWER MODULE COOLING) FIGURE 11 FORCED CONVECTION DERATING, POWER DISSIPATION VERSUS LOCAL AMBIENT TEMPERATURE KFD 62528W/060801...