riedon inc. 300 cypress avenue alhambra ca 91801 (626) 284-9901 (626) 284-1704 www.riedon.com 11/10 pf1260 series ? to-126 housing ? resistances from 0.01 to 51k ohms ? rated power to 20 watts ? resistance tolerances to 0.05% ? tcr to 5ppm/k ? 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 : PF1262 -55c to +120c : pf1261 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 PF1262 20w 1w 5.9k/w 0.01 w 51k w 1% ( r 0.1 w ) 5% 50ppm/c ( r 10 w ) 100ppm/c ( 0.1 w r < 10 w ) 250ppm/c ( r < 0.1 w ) pf1261 5w 0.5w 6.0k/w 0.1 w 51k w 0.1%, 0.25% ( r 5 w ) 0.5% ( r 1 w ), 1% 5ppm/c ( r 1 w ) 25ppm/c ( r <1 w ) to-126 power film resistors
riedon inc. 300 cypress avenue alhambra ca 91801 (626) 284-9901 (626) 284-1704 www.riedon.com 11/10 part number - resistance - tolerance - tcr example: PF1262 0.5 ohm 1% 100ppm specifications (continued) power rating notes - the pf1260 series film resistors must be attached to a suit - able heatsink. the maximum internal resistor temperature is 155c (120c for the pf1261). 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 ( k/w ) r q r = thermal resistance of resistor ( k/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) pf1261 PF1262 power derating curve mounting notes - the pf1260 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 nm ). back plate is isolated from both pins. pf1260 series to-126 power film resistors ordering information
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