Holtek ht9170 dtmf receiver holtek ht9170b dtmf receiver 2 5v to 5 5v supply voltage 10ua standby current 3 58mhz system frequency 3ma operating current 2 5ma output drive current 100kr pull high resistance 20 to 75 c 18 dip case the ht9170b d are dual tone multi frequency dtmf receivers integrated with digital decoder and band split filter functions as well as power down mode and inhibit mode operations such devices use digital counting techniques to detect and decode all the 1