H11F1M, H11F2M, H11F3MTYPICAL APPLICATIONSAs a Variable ResistorAs an Analog Signal Switch ISOLATED VARIABLE ATTENUATORS ISOLATED VARIABLE ATTENUATORS 500K + VIN V − V VOUT OUT IN VIN 50 VIN VOUT IF H11F1M H11F1M H11F1M I C F IF VOUT t LOW FREQUENCY HIGH FREQUENCY IF Dynamic Range 70 db Dynamic Range 50 db @ 10 kHz For 0 ≤ I @ 1 MHz F ≤ 30 mA For 0 ≤ IF ≤ 30 mA Distortion free attenuation of low level A.C. signals is accomplished Accuracy and range are improved over conventional FET by varying the IRED current, IF Note the wide dynamic range and switches because the H11FXM has no charge injection from the absence of coupling capacitors; D.C. level shifting or parasitic control signal. The H11FXM also provides switching of either feedback to the controlling function. polarity input signal up to 30V magnitude. AUTOMATIC GAIN CONTROL MULTIPLEXED, OPTICALLY−ISSOLATED A/D CONVERSION CALL V1 H11F1M V CALL IN VOUT V + n V1 H74A1 − V2 MSB MSB A/D PROCESS CONTROL H11F1M V CONVERTER 500K n LSB H74A1 DATA INPUT LOGIC LSB SYSTEM IF H11F1M AGC SIGNAL This simple circuit provides over 70db of stable gain control for an AGC signal range of from 0 to 30mA. This basic circuit can be used to provide programmable fade and attack for electronic music. The optical isolation, linearity and low offset voltage of the H11FXM allows the remote multiplexing of low level analog signals from such transducers as thermocouplers, Hall effect devices, strain gauges, etc. to a single A/D converter. ACTIVE FILTER FINE TUNING/BAND SWITCHING TEST EQUIPMENT − KELVIN CONTACT POLARITY I H11F1M F2 IF2 H11F1M I H11F1M H11F1M F IF A C I I TEST F TO A1 A & B FOR A2 DEVICE PARAMETER A3 UNDER SENSING POLARITY 1 TEST BOARD C & D FOR POLARITY 2 B D IF IF H11F1M H11F1M IF2 ADJUSTS f1, IF2 ADJUSTS f2 In many test equipment designs the auto polarity function uses The linearity of resistance and the low offset voltage of the reed relay contacts to switch the Kelvin Contact polarity. H11FXM allows the remote tuning or band−switching of active These reeds are normally one of the highest maintenance cost filters without switching glitches or distortion. This schematic items due to sticking contacts and mechanical problems. The illustrates the concept, with current to the H11F1M IRED ’s totally solid−State H11FXM eliminates these troubles while controlling the filter’s transfer characteristic. providing faster switching. www.onsemi.com5