MC14517 View Datasheet(PDF) - Motorola => Freescale

Part Name

Description

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MC14517

Dual-Band PLL Frequency Synthesizer with ADC and Frequency Counter

Motorola => Freescale 

Frequency and Phase of fV = fR: essentially a floating

state; voltage at pin determined by loop filter

This output is enabled and disabled via the HF/VHF bit in

the R register. VHF PDout is forced to the floating state when

disabled.

If not used, this pin should be a no connect.

Rx

External Resistor (Pin 20)

A resistor is tied between this pin and VSS. This sets a ref-

erence current which determines the current delivered

(I PDout) at the current source/sink phase/frequency detector

output, VHF PDout. For a nominal current of 2.2 mA at the

VHF PDout pin, a 15 kΩ resistor is utilized.

In addition, the Rx pin must be bypassed to VDD with a

low–inductance 0.1 µF capacitor mounted very close to

these pins. Lead lengths on the capacitor should be mini-

mized.

If the VHF PDout pin is not used, the Rx pin may be floated.

POWER SUPPLY

VDD

Most–Positive Supply Potential (Pin 17)

This pin may range from 4.5 to 5.5 V with respect to VSS.

For optimum performance, VDD should be bypassed to

VSS using low–inductance capacitor(s) mounted very close

to the MC145173. Lead lengths and traces to the capaci-

tor(s) should be minimized. (The very fast switching speed of

the device can cause excessive current spikes on the power

leads if they are improperly bypassed.)

Power supply ramp up time should be less than 20 ms

from 0 to 4.5 V. If the ramp up time exceeds 20 ms, the POR

circuit may not function and the outputs will be in an unknown

state. The RST bit must be used in this case.

VSS

Most–Negative Supply Potential (Pin 19)

This pin is usually ground.

fR

REFERENCE

OSCin ÷ R

fV

FEEDBACK

(fin ÷ N)

HF PDout

VHF PDout

VH

VL

VH

VL

*

VH

HIGH IMPEDANCE

VL

*

SOURCING CURRENT

FLOAT

SINKING CURRENT

VH = High voltage level

VL = Low voltage level

*At this point, when both fR and fV are in phase, both the source and sink drivers are turned on for a short duration. For exceptions,

see Figure 19.

NOTE: HF PDout and VHF PDout are shown with the polarity bit (POL) = low; see Figure 18 for POL.

Figure 16. Phase/Frequency Detectors Output Waveforms

MOTOROLA

MC145173

11

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