FS8170

Page 2

July 2005

Pin Descriptions

Functional Block Diagram

Number

Name

I/O

Description

1

XIN

I

Reference crystal oscillator or external clock input with internally biased amplifier

2

XOUT

O

Reference crystal oscillator output

3

VP

—

Power supply voltage for the charge pump

4

VCC

—

Power supply voltage

5

DO

O

Single-ended charge pump output

6

VSS

—

Ground

7

XFIN

I

Complementary input for prescaler (normally ac-bypassed via a capacitor)

8

FIN

I

VCO frequency input with internally biased input amplifier

9

CLK

I

Shift register clock input

10

DATA

I

Serial data input

11

LE

I

Load enable signal input

12

EN

I

Power-down control

13

ZC

I

Forced high-impedance control for the charge pump

14

FOLD

O

Multiplexed CMOS level output (see Functional Description section for programming infor-

mation)

15

φP

O

Phase comparator N-channel open drain output for an external charge pump

16

φR

O

Phase comparator CMOS inverter output for an external charge pump

PFD

LD MUX

FIN

DATA

CLK

LE

CONTROL

LOGIC

SHIFT REGISTER

FOLD

DO

LOCK

DETECTOR

EN

N-LATCH

N-COUNTER

R-COUNTER

CHARGE

PUMP

OSC

N-PRESCALER

XOUT

XIN

R-LATCH

XFIN

φR

φP

ZC