GS-R1005 50w step-down switching regulator june 1994 1/7 type v i v o i o GS-R1005 12 to 36 v 5 v 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 volt age 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 /10a output voltage from a wide i nput voltage range (12 to 36v). absolute maximum ratings symbol parameter value unit v i dc input voltage 40 v v iinh high inhibit voltage 28 v t cop operating case temperature range 0 to +75 c t stg storage temperature range C 20 to +105 c
electrical characteristics (t amb = 25 c unless otherwise specified) symbol parameter test conditions min typ max unit v i input voltage v o = 5.05v i o = 1.2 to 10a 12 24 36 v l i input current v i = 24v i o = 10a 2.5 a l ir reflected input current v i = 24v i o = 10a with external filter (c = 470 m f) 200 220 mapp v ien enable input voltage v i = 12 to 36v i o = 1.2 to 10a 01.2v v iinh inhi bit input voltage v i = 12 to 36v i o = 1.2 to 10a 224v l iinh inhi bit input current v i = 12 to 36v i o =1.2 to 10a v iinh = 5v 0.3 0.5 ma v o output voltage v i = 12 to 36v i o = 1.2 to 10a 4.9 5.05 5.2 v v or output ripple voltage v i = 24v i o = 10a 100 120 mvpp d v ol line regu lation v i = 12 to 36v i o = 10a 0.5 % d v oo load regulation v i = 24v i o = 1.2 to 10a 1% d v o total remote sense compensation v i = 24v i o = 10a 0.5 v i o output current * v i = 12 to 36v v o = 5.05v 010a i ol output current limiting v i = 12 to 36v 12.5 13.7 a i osc short-circuit output current v i = 24v 16 a d i o current sharing deviation v i = 24v i o = 2 to 10a two modules in parallel 10 % t ss soft-start time v i = 24v i o = 10a 15 ms tr1 line transient recovery time v i = 12 to 36v i o = 5a 60 m s tr2 load transient recovery time v i = 24v i o = 1.2 to 10a 100 m s f s switching frequency v i = 24v i o = 1.2 to 10a 100 khz h efficiency v i = 12 to 36v i o = 10a 80 83 % r thc thermal resistance case-to-ambient 7.5 c/w * note: when output current is less than 1.2a, output ripple voltage increases due to discontinuous operation. 2/7 GS-R1005
3/7 package r. dimensions in mm (inches). connection diagram and mechanical data pin description pin function description 1 gnd input return for input voltage source. internally connected to pin 10,11. 2 inhibit the converter is on (enable) when this pin is un conn ected 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 v oltage is 36v. external capacitor between pin 3 and pin 1 is mandatory; recommended value is 470 m f/50v for switching application. 4,5 + vout +5v output voltage. 6 + sense senses the remote load high side. to be connected to pin 4,5 when remote sense is not used. 7sync synchronization output. see figures 1,2,3,4. open when not used. 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 confi guration, take care to connect all -s pins together (see figures 1,2,3,4). 10,11 gnd output return for output current path. internally connected to pin 1. GS-R1005
4/7 user notes input voltage the recommended operating maximum dc input voltage is 36v inclusive of the ripple voltage. the use of an ex ternal low esr, high ripple current capacitor located as close the module as possible is mandatory; recommended value is 470 m f/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 fi gures 1, 2, 3, 4. parallel operation to increase available output regulated power, the module features the parallel connection possibility with equal cur rent sharing and maximum deviation of 10% (two modules in parallel). see the connec- tion 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, avoid- ing latch-up problems with certain types of l oads. figure 1. figure 2. GS-R1005
5/7 thermal characteristics: how to choose the heat-sink sometimes the GS-R1005 requires an external heat-sink depending on both operating temperature conditions and power. before entering into calculati ons details, some ba- sic concepts will be explained to better understand the problem. the thermal resistance between two points is rep- resented 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 am- bient 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 ambi ent temperature. the maximum case temperature, at which the mod- ule provides 10a, is 75 c (see fig. 6). lets 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: t case = t amb + p d r th = 40 + 10.2 7.5 = 116.8 c this value exceeds the maximum allowed tempera- ture 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, lets first determine what the total thermal resistance should be. r th = t casemax - t amb p d = 75 - 40 10.2 = 3.42 c / w this value is the resulting value of the additional heatsink thermal resistance. figure 3. figure 4. GS-R1005
6/7 figure 6. - output current vs. t case. 80 81 82 83 84 85 86 87 88 89 90 0 1 2 3 4 5 6 7 8 9 10 typ. eff. (%) vi= 12v vi= 24v vi= 36v figure 5. - efficiency vs. output current. 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 manufacturers type height (mm) rth ( c/w) alutronic pr139 20 3 pr140 19 2 pr159 20 2.5 assman v5440 19 3 v5805 15 2 v5280 19 2 aavid 60885 14 4.5 60660 25.5 1.5 62355 33.5 3 austerlitz ks50 12 3 ks100.3 15 2.5 fischer sk16 25.5 1.5 sk52 19 2 sge bosari l30 21 3 lz50 24 3 thermalloy 6155 14 4.5 6601 14 5 6176 24 4.5 6320 30 1.5 7/7 custom made heat-sink that can be experimently designed and tested. information furnished is believed to be a ccurate 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 pa rties 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 pro ducts 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 C all r ights reserved sgs-thomson m icroelectronics group of comp anies australia - brazil - china - france - germany - hong kong - italy - japan - korea - malaysia - malta - morocco - the netherland s - singapore - spain - sweden - switzerland - taiwan - thailand - united kingdom - u.s.a. GS-R1005
|
