GS-R1012

GS-R1012 120W STEP-DOWN SWITCHING REGULATOR Type GS-R1012 Vi 18 to 36 V Vo 12 V Io 10 A FEATURES Wide input voltage range (18 to 36V) High efficiency (90% 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-R1012 is a step-down switching voltage regulator suitable to provide 12V/10A output voltage from a wide input voltage range (18 to 36V). ABSOLUTE MAXIMUM RATINGS Symbol Vi Viinh Tstg Tcop DC Input Voltage High Inhibit voltage Storage Temperature Range Operating Case Temperature Range Parameter Value 40 28 – 20 to +105 0 to +75 Unit V V °C °C June 1994 1/7 GS-R1012 ELECTRICAL CHARACTERISTICS (Tamb = 25°C unless otherwise specified) Symbol Vi li lir Vien Viinh liinh Vo Vor δVOL δVOO ∆ Vo Io Iol Iosc δI o Parameter Input Voltage Input Current Reflected Input Current Enable Input Voltage Inhibit Input Voltage Inhibit Input Current Output Voltage Output Ripple Voltage Line Regulation Load Regulation Remote Sense Compensation Output Current* Output Current Limiting Short-circuit Output Current Current Sharing Deviation Soft-start Time Line Transient Recovery Time Load Transient Recovery Time Switching Frequency Efficiency Thermal Resistance Case-to-ambient Test Conditions Vo = 12V Vi = 24V Io = 1.5 to 10A Io = 10A Min 18 Typ 24 5,6 400 0 2 0.3 11.4 12 150 0.5 1 0.5 Vo = 12V 0 10.5 10 11.5 16 10 500 1.2 24 0.5 12.6 Max 36 Unit V A mApp V V mA V mVpp % % V A A A % Vi = 24V Io = 10A with external filter (C = 1000µF) Vi = 18 to 36V Io = 1.5 to 10A Vi = 18 to 36V Io = 1.5 to 10A Vi = 18 to 36V Io =1.5 to 10A Viinh = 5V Vi = 18 to 36V Io = 1.5 to 10A Vi = 24V Io = 10A Vi = 18 to 36V Io = 10A Vi = 24V Vi = 24V Io = 10A Vi = 18 to 36V Vi = 18 to 36V Vi = 24V Vi = 24V Io = 2 to 10A two modules in parallel Vi = 24V Io = 10A Io = 1.5 to 10A tss tr1 tr2 fs η R thc 15 60 100 100 90 92 7.5 ms µs µs kHz % °C/W Vi = 15 to 36V Io = 5A Vi = 24V Vi = 24V Io = 1.5 to 10A Io = 1.5 to 10A Io = 10A Vi = 18 to 36V * Note: when output current is less than 1.5A, output ripple voltage increases due to discontinuous operation. 2/7 GS-R1012 CONNECTION DIAGRAM AND MECHANICAL DATA Dimensions in mm (inches). PIN DESCRIPTION Pin 1 2 3 4,5 6 7 8 9 10,11 Function GND Input Inhibit + Vin + Vout + Sense Sync Parallel - Sense GND Output Description Return for input voltage source. Internally connected to pin 10,11. 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. DC Input voltage; recommended maximum voltage is 36V. External capacitor between pin 3 and pin 1 is mandatory; recommended value is 1000µF/50V for switching application. +12V output voltage. 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. Take care to leave the pin open when is not used. Parallel output. See figures 1,2,3,4. Take care to leave the pin open when is not used. 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). Return for output current path. Internally connected to pin 1. 3/7 GS-R1012 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 1000µF/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. 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 1. Figure 2. 4/7 GS-R1012 Figure 3. Figure 4. Thermal characterist ics: how to choose the heat-sink Sometimes the GS-R1012 requires an external heat-sink depending both operating temperature 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-R1012 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 to which the module provides 10A is 75°C (see fig. 6). Let’s suppose to have a GS-R1012 that delivers a load current of 10A at an ambient temperature of 40°C. The dissipated power in this operating condition is about 10.4W (at typical efficiency of 92%), and the case temperature of the module will be: TCase = TAmb + Pd × Rth = 40 + 10.4 × 7.5 = 118°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 = 3.37°C / W Pd 10.4 This value is the resulting value of the additional heatsink thermal resistance. 5/7 GS-R1012 Figure 5. - Efficiency vs. Output Current. Typ. eff. (%) 98 97 96 95 94 Vi= 18V 93 92 91 90 89 88 0 1 2 3 4 5 6 7 8 9 10 Vi= 36V Vi= 24V Figure 6. - Output Current vs. T case. 6/7 GS-R1012 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 ALUTRONIC Type PR139 PR140 PR159 Height (mm) 20 19 20 19 15 19 14 25.5 33.5 12 15 25.5 19 21 24 14 14 24 30 Rth (°C/W) 3 2 2.5 3 2 2 4.5 1.5 3 3 2.5 1.5 2 3 3 4.5 5 4.5 1.5 ASSMAN V5440 V5805 V5280 AAVID 60885 60660 62355 AUSTERLITZ KS50 KS100.3 FISCHER SK16 SK52 SGE BOSARI L30 LZ50 THERMALLOY 6155 6601 6176 6320 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