GS-R1005 50W STEP-DOWN SWITCHING REGULATOR Type GS-R1005 Vi Vo Io 12 to 36 V 5V 10 A FEATURES Wide input voltage range (12 to 36V) High efficiency (80% min.) Parallel operation with current sharing Synchronization Remote inhibit/enable Remote load voltage sense Output short-circuit protection Soft-start PCB or chassis mountable DESCRIPTION The GS-R1005 is a step-down switching voltage regulator suitable to provide 5V/10Aoutput voltage from a wide input voltage range (12 to 36V). ABSOLUTE MAXIMUM RATINGS Symbol Value Unit DC Input Voltage 40 V Viinh High Inhibit voltage 28 V Tcop Operating Case Temperature Range 0 to +75 °C Tstg Storage Temperature Range – 20 to +105 °C Vi June 1994 Parameter 1/7 GS-R1005 ELECTRICAL CHARACTERISTICS (Tamb = 25°C unless otherwise specified) Parameter Symbol Test Conditions Vi Input Voltage Vo = 5.05V li Input Current Vi = 24V Io = 1.2 to 10A lir Reflected Input Current Vi = 24V Io = 10A with external filter (C = 470µF) Min 12 Io = 10A Typ Max 24 36 2.5 200 Unit V A 220 mApp Vien Enable Input Voltage Vi = 12 to 36V Io = 1.2 to 10A 0 1.2 V Viinh Inhibit Input Voltage Vi = 12 to 36V Io = 1.2 to 10A 2 24 V liinh Inhibit Input Current Vi = 12 to 36V Io =1.2 to 10A Viinh = 5V 0.5 mA Vo Output Voltage Vi = 12 to 36V Io = 1.2 to 10A Vor Output Ripple Voltage Vi = 24V Io = 10A Line Regulation Vi = 12 to 36V Io = 10A δVOL δVOO Load Regulation Vi = 24V ∆Vo Total Remote Sense Compensation Vi = 24V Io = 10A Io Output Current* Vi = 12 to 36V Iol Output Current Limiting Vi = 12 to 36V Iosc Short-circuit Output Current δIo 0.3 4.9 5.2 V 100 120 mVpp 0.5 % Io = 1.2 to 10A 1 % 0.5 V 0 10 A 12.5 13.7 A Vi = 24V 16 A Current Sharing Deviation Vi = 24V Io = 2 to 10A two modules in parallel 10 % tss Soft-start Time Vi = 24V tr1 Line Transient Recovery Time tr2 fs η R thc Vo = 5.05V Io = 10A 15 ms Vi = 12 to 36V Io = 5A 60 µs Load Transient Recovery Time Vi = 24V Io = 1.2 to 10A 100 µs Switching Frequency Vi = 24V Io = 1.2 to 10A 100 kHz Efficiency Vi = 12 to 36V Io = 10A 80 Thermal Resistance Case-to-ambient * Note: when output current is less than 1.2A, output ripple voltage increases due to discontinuous operation. 2/7 5.05 83 % 7.5 °C/W GS-R1005 CONNECTION DIAGRAM AND MECHANICAL DATA Package R. Dimensions in mm (inches). PIN DESCRIPTION Pin Function Description 1 GND Input 2 Inhibit The converter is ON (Enable) when this pin is unconnected or the voltage applied is lower than 1.2V. The converter is OFF (Inhibit) for a control voltage in the range of 2 to 24V. 3 + Vin DC Input voltage; recommended maximum voltage is 36V. External capacitor between pin 3 and pin 1 is mandatory; recommended value is 470µF/50V for switching application. 4,5 + Vout +5V output voltage. 6 + Sense 7 Sync 8 Parallel Parallel output. See figures 1,2,3,4. Open when not used. 9 - Sense Senses the remote load return. To be connected to pin 10,11 when remote sense is not used. In parallel configuration, take care to connect all -S pins together (see figures 1,2,3,4). 10,11 GND Output Return for input voltage source. Internally connected to pin 10,11. Senses the remote load high side. To be connected to pin 4,5 when remote sense is not used. Synchronization output. See figures 1,2,3,4. Open when not used. Return for output current path. Internally connected to pin 1. 3/7 GS-R1005 USER NOTES Input Voltage The recommended operating maximum DC input voltage is 36V inclusive of the ripple voltage. The use of an external low ESR, high ripple current capacitor located as close the module as possible is mandatory; recommended value is 470µF/50V. Softstart To avoid heavy inrush current the output voltage rise time is typically 15ms in any condition of load. Remote Sensing The remote voltage sense compensation range is for a total drop of 500mV equally shared between the load connecting wires. It is a good practice to shield the sensing wires to avoid oscillations. See the connection diagram on figures 1, 2, 3, 4. Figure 1. 4/7 Parallel Operation To increase available output regulated power, the module features the parallel connection possibility with equal current sharing and maximum deviation of 10% (two modules in parallel). See the connection diagram on figures 1, 2, 3, 4. Module Protection The module is protected against occasional and permanent shortcircuits of the output pins to ground, as well as against output current overload. It uses a current limiting protection circuitry, avoiding latch-up problems with certain types of loads. Figure 2. GS-R1005 Figure 3. Figure 4. Thermal characterist ics: how to choose the heat-sink Sometimes the GS-R1005 requires an external heat-sink dependingon both operatingtemperature conditions and power. Before entering into calculations details, some basic concepts will be explained to better understand the problem. The thermal resistance between two points is represented by their temperature difference in front of a specified dissipated power, and it is expressed in Degree Centigrade per Watt (°C/W). For GS-R1005 the thermal resistance case to ambient is 7.5°C/W. This means that an internal power dissipation of 1W will bring the case temperature at 7.5°C above the ambient temperature. The maximum case temperature, at which the module provides 10A, is 75°C (see fig. 6). Let’s suppose to have a GS-R1005 that delivers a load current of 10A at an ambient temperature of 40°C. The dissipated power in this operating condition is about 10.2W (at typical efficiency of 83%), and the case temperature of the module will be: TCase = TAmb + Pd × Rth = 40 + 10.2 × 7.5 = 116.8 °C This value exceeds the maximum allowed temperature and an external heat-sink must be added. To this purpose four holes (see mechanical drawing) are provided on the metal surface of the module. To calculate this heat-sink, let’s first determine what the total thermal resistance should be. Rth = TCaseMAX − Tamb = 75 − 40 = 3.42°C / W Pd 10.2 This value is the resulting value of the additional heatsink thermal resistance. 5/7 GS-R1005 Figure 5. - Efficiency vs. Output Current. Typ. eff. (%) 90 89 Vi= 12V 88 87 86 Vi= 24V 85 84 Vi= 36V 83 82 81 80 0 1 2 3 Figure 6. - Output Current vs. T case. 6/7 4 5 6 7 8 9 10 GS-R1005 The following list may help the designer to select the proper commercially available heat-sink. Sometimes it can be more convenient to use a custom made heat-sink that can be experimently designed and tested. Manufacturers Type ALUTRONIC PR139 20 3 PR140 19 2 PR159 20 2.5 V5440 19 3 V5805 15 2 V5280 19 2 60885 14 4.5 60660 25.5 1.5 ASSMAN AAVID AUSTERLITZ FISCHER SGE BOSARI THERMALLOY Height (mm) Rth (°C/W) 62355 33.5 3 KS50 12 3 KS100.3 15 2.5 SK16 25.5 1.5 SK52 19 2 L30 21 3 LZ50 24 3 6155 14 4.5 6601 14 5 6176 24 4.5 6320 30 1.5 Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the consequences of use of such information nor for any infringement 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 SGS-THOMSON Microelectronics. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. 1994 SGS-THOMSON Microelectronics – All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A. 7/7