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The new MC145170-2 is pin-for-pin compatible with the MC145170-1. 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 μAadditional supply current. Note that the maximum specification of 100 μAquiescent 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 patented 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.

The device features fully programmable R and N counters, an amplifier at the f_in pin, on-chip support of an external crystal, a programmable reference output, and both single- and double-ended phase detectors with linear transfer functions (no dead zones). A configuration (C) register allows the part to be configured to meet various applications. A patented feature allows the C register to shut off unused outputs, thereby minimizing noise and interference.

In order to reduce lock times and prevent erroneous data from being loaded into the counters, a patented jam-load feature is included. Whenever a new divide ratio is loaded into the N register, both the N and R counters are jam-loaded with their respective values and begin counting down together.The phase detectors are also initialized during the jam load.