? 2007 teledyne relays (800) 284-7007 ? www.teledynerelays.com page 2dsLPD70 rev. b LPD70 series 250ma, 28vdc optically isolated dual relay features/benefits ? current limiting output ? thermal protection ? automatic recovery ? overload protection ? dual output: two relays in one package ? low voltage drop description the LPD70 is a dual-output 28vdc plastic relay with internal thermal protection. the relay utilizes optical isolation to provide excellent input-to-output isolation. the LPD70 offers a current limiting output to protect itself and associated load circuits from transient current overloads. during an overcurrent condition, the LPD70 clamps the current to a safe operating value. the LPD70 also offers thermal protection. the thermal protection is activated by junction temperature. in case of an overload or shorted load condition, the thermal protection limits the junction temperature. the LPD70 returns to normal operation automatically once the overload is removed. part number description LPD70 250ma, 28vdc dual solid-state relay input (control) specifications (C40 to 85c) min max units control voltage range 4.0 7.0 vdc (see note ) input current @ 5 vdc (see fig 2) 2 ma must turn-on voltage 4 vdc must turn-off voltage 0.8 vdc must turn-off current 50 a reverse voltage C7 vdc mechanical specification figure 1 C LPD70 relay; dimensions in inches (mm) tolerances are +/- .005 inch (.127) unless otherwise specifed input current vs. input voltage figure 2 ) n p u t # u r r e n t m ! ) n p u t 6 o l t a g e 6 d c maximum
page 2 s pecifications under revision control ? 2007 teledyne relays 2dsLPD70 rev. b LPD70 series 250ma, 28vdc optically isolated dual relay typical overload current vs. temperature figure 5 environmental specifications min max units operating temperature C40 +85 c storage temperature C55 +00 c junction temperature 00 c thermal resistance (junction to ambient) each relay 20 c/w shock 500 g vibration 00 g dielectric strength 500 vac insulation resistance (@500 vdc) 0 9 ohm isolation 5 pf resistance to solder dip, 0 seconds at +260c soldering heat mil std 202, method 20 solderability mil std 202, method 208 thermal shock mil std 202, method 07 hast jedec test method a 0 30c 85% rh, no power applied, 50 hours output (load) specifications min max units load voltage rating 33 vdc load current (see fig 6) 0.25 a transient voltage 80 vdc transient supply voltage with load shorted (5 sec max) 46 vdc output capacitance @ 25vdc 200 pf on-state voltage drop (see fig 4) 0.5 vdc on resistance 2.0 ohm off-state leakage current (33vdc) 0 a turn-on time 2.5 ms turn-off time ms overload current limit (see fig 5) 0.9 a load current vs. output voltage drop over temperature figure 4 overload/thermal protection specifications (note 8) min typical max units output load voltage 33 vdc junction activation 50 c temperature output current (after 20 sec) 60 marms activation time (see fig. 7, note7) 70 ms typical wiring diagram figure 3 n n n n ! m b i e n t 4 e m p e r a t u r e ? # / v e r l o a d # u r r e n t , i m i t ! 2 % , ! 9 ! ) . / 5 4 n n / 5 4 ) . n n 2 % , ! 9 " 0 ) . 6 6 , o a d ! , o a d " 6 s u p p l y 6 d c 4 y p i c a l 6 d c n o # o # o # / u t p u t 6 o l t a g e $ r o p 6 , o a d # u r r e n t !
? 2007 teledyne relays (800) 284-7007 ? www.teledynerelays.com page 3 2dsLPD70 rev. b LPD70 series 250ma, 28vdc optically isolated dual relay typical overload current vs. time figure 7 notes . for input voltages greater than 7 volts, use an external resistor in series with the relay input. r ext . = (v in C7 vdc)/0.0 2 amps 2. relay input voltage transitions should be less than .0 millisecond. 3. above approximately 0.6 amps load (overload), the relay becomes current limited. in this mode of operation, the voltage across the relay contacts is: v contact ? v supply C [(0.6 amp) (r load )] the relay will limit current in an overload condition until the overload is removed. 4. maximum load current ratings are with the relay in free air and soldered to a printed circuit board. 5. loads may be attached to either the positive or negative output terminal. 6. timing is measured from the input voltage transition to the 0% or 90% points on the output voltage transition. 7. activation time is the time for the thermal protection circuit to take effect. 8. the LPD70 relay withstands shorted loads at 33 vdc max supply voltage indefnitely, and survives shorted load conditions at 46 vdc max supply voltage for 5 seconds max. functional block diagram figure 8 load current vs. ambient temperature figure 6 n n ! m b i e n t 4 e m p e r a t u r e ? # , o a d # u r r e n t ! theory of operation LPD70 relays operate with 0.25 amp loads from C40 to +85c. overloads are current-limited to about 0.6 amps. a temperature sense circuit in intimate contact with the output power switch opens the switch at elevated junction temperatures. this thermal shutdown results in a periodic cycling of the output switch, with the overload current decaying over time. once the overload is removed, the relay returns to normal operation. the LPD70 relay survives overloads, including shorted loads, at load voltages up to 33vdc. ) . ) . 0 5 4 w i t h , % $ / p t i c a l ) s o l a t i o n $ e t e c t i o n # i r c u i t 4 u r n / f f 4 e m p e r a t u r e 3 e n s e 4 i m i n g # i r c u i t / u t p u t 3 w i t c h - / 3 & % 4 w i t h # u r r e n t , i m i t n ) . / 5 4 n / 5 4 s e c o n d s - i l l i s e c o n d s / u t p u t # u r r e n t w i t h , o a d 3 h o r t e d ! m p s activation time
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