NB2872A

http://onsemi.com

2

Figure 1. Block Diagram

ModOUT

Crystal

Oscillator

Frequency

Divider

Feedback

Divider

Phase

Detector

Loop

Filter

XIN/CLKIN

XOUT

REFOUT

Modulation

Output

Divider

PLL

Table 1. KEY SPECIFICATIONS

Description

Specification

Supply Voltages

Frequency Range

15 MHz < CLKIN < 30 MHz

Cycle−to−Cycle Jitter

300 ps (maximum)

Output Duty Cycle

40 / 60% (worst case)

Output Rise and Fall Times

1.1 ns (maximum)

Modulation Equation

Frequency Deviation

−1.25%

Figure 2. Pin Configuration

1

2

3

6

5

4

REFOUT

XOUT

XIN/CLKIN

ModOUT

NB2872A

Table 2. PIN DESCRIPTION

Pin #

Pin Name

Type

Description

1

REFOUT

O

Buffered output of the input frequency.

2

XOUT

O

Crystal connection. If using an external reference, this pin must be left unconnected.

3

XIN/CLKIN

I

Crystal connection or external reference frequency input. This pin has dual functions. It can be

connected either to an external crystal or an external reference clock

4

P

Power supply for the entire chip (3.3 V).

5

ModOUT

O

Spread spectrum clock output.

6

P

Ground connection.