riedon inc. 300 cypress avenue alhambra ca 91801 (626) 284-9901 (626) 284-1704 www.riedon.com 11/10 PF2470 series ? to-247 housing ? rated power to 140 watts ? resistances from 0.01 to 51k ohms ? high stability film resistance elements ? resistance tolerance to 0.05% ? low inductance ( <50nh ) ? isolated back plate specifications 1 power rating based on 25c flange temperature 2 power rating based on 25c ambient temperature 3 consult factory for higher or lower values specifcation value maximum current 25a temperature range -55c to +155c dielectric strength 2000 vac max. operating voltage 500 v insulation resistance >1000 meg-ohm environmental performance d r test conditions load life 1% + 0.05 w 25c, 90 min on, 30 min off, 1000 hr humidity resistance 1% + 0.05 w 40c, 90-95% rh, dc 0.1w, 1000 hr temperature cycle 0.25% + 0.05 w -55c for 30 min, +155c for 30 min, 1000 hr solder heat 0.1% + 0.05 w +350c, 3s vibration 0.25% + 0.05 w iec60068-2-6 type power rating heatsink 1 free air 2 thermal resistance resistance range 3 min max tolerances temperature coeffcients pf2473 140w 5w 0.9c/w 0.01 w 51k w 1% ( r 0.10 w ) 5% 50ppm/c ( r 10 w ) 100ppm/c ( 0.1 w r < 10 w ) 250ppm/c ( r < 0.1 w ) pf2472 100w 3w 1.3c/w 0.01 w 51k w 1% ( r 0.10 w ) 5% 50ppm/c ( r 10 w ) 100ppm/c ( 0.1 w r < 10 w ) 250ppm/c ( r < 0.1 w ) to-247 power film resistors
riedon inc. 300 cypress avenue alhambra ca 91801 (626) 284-9901 (626) 284-1704 www.riedon.com 11/10 specifications (continued) power rating notes - the PF2470 series foil resistors must be attached to a suitable heatsink. the maximum internal resistor temperature is 155c (120c for the pf2201). to specify an appropriate heatsink use the following formula : r q h = t max - ( p x r q r ) - t a p where: r q h = thermal resistance of heatsink ( c/w ) r q r = thermal resistance of resistor ( c/w ) t max = maximum temperature of resistor t a = ambient temperature of heatsink ( c ) p = power through resistor ( w ) -25 0 25 50 75 100 125 150 175 0 20 40 60 80 100 120 power ( % ) ambient temperature (c) power derating curve mounting notes - the PF2470 series film resistors must be attached to a suit - able heatsink. mount resistor using thermal grease to a clean, fat surface. use a compression washer to provide 150 to 300 pounds ( 665 to 1330n ) of mounting force. torque mounting screw to 8 in-lbs ( 0.9 n-m ). back plate is isolated from both pins. PF2470 series to-247 power film resistors part number - resistance - tolerance - tcr example: pf2472 10 ohm 1% 50ppm ordering information
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