Pin Connections

MC145170-2 Technical Data, Rev. 5

Freescale Semiconductor

11

from each pin to ground (up to a maximum of 30 pF each, including stray capacitance). An external

feedback resistor of 1.0 to 5.0 M

Ω is connected directly across the pins to ensure linear operation of the

amplifier. The required connections for the components are shown in Figure 11.

5 M

The external signal level must be at least 1 Vpp; the maximum frequencies are given in Table 6, the Loop

Specifications table on page 7. These maximum frequencies apply for R Counter divide ratios as indicated

in the table. For very small ratios, the maximum frequency is limited to the divide ratio times 2 MHz.

(Reason: the phase/frequency detectors are limited to a maximum input frequency of 2 MHz.)

avoid loading an internal node on the device, as noted above. For frequencies below 1 MHz, dc coupling

must be used. The R counter is a static counter and may be operated down to dc. However, wave shaping

Reference Frequency Output (Pin 3)

This output is the buffered output of the crystal-generated reference frequency or externally provided

reference source. This output may be enabled, disabled, or scaled via bits in the C register (see Figure 16).

If unused, the pin should be floated and should be disabled via the C register to minimize dynamic power

consumption and electromagnetic interference (EMI).

3.3

Counter Output Pins

R Counter Output (Pin 9)

(patented). The output is disabled (static low logic level) upon power up. If unused, the output should be

left disabled and unconnected to minimize interference with external circuitry.

determined by the binary value loaded into the R register. Also, direct access to the phase detector via the