PLL Frequency Synthesizer with Serial Interface

The new MC145170–2 is pin–for–pin compatible with the MC145170–1. A comparison of the two parts is shown in the table below. The MC145170–2 is recommended for new designs and has a more robust power–on reset (POR) circuit that is more responsive to momentary power supply interruptions. The two devices are actually the same chip with mask options for the POR circuit. The more robust POR circuit draws approximately 20 mA additional supply current. Note that the maximum specification of 100 mA quiescent supply current has not changed. The MC145170–2 is a single–chip synthesizer capable of direct usage in the MF, HF, and VHF bands. A special architecture makes this PLL easy to program. Either a bit– or byte–oriented format may be used. Due to the BitGrabber^TM registers, no address/steering bits are required for random access of the three registers. Thus, tuning can be accomplished via a 2–byte serial transfer to the 16–bit N register.