AD9574 datasheet(30/35 Pages) AD

30 / 35 page

AD9574

Data Sheet

Rev. B | Page 30 of 35

APPLICATIONS INFORMATION

DUAL OSCILLATOR REFERENCE INPUT

APPLICATION

Figure 24 depicts a typical application diagram using two

crystal oscillators (XOs) as the reference inputs. A stable

oscillator source supplies the MCLK_x inputs and serves as the

timing reference for the on-board reference monitoring

function. A field-programmable gate array (FPGA) handles the

control interface for monitoring the status of the references and

the PLL (lock detector) and for switching between references as

required. The FPGA also controls the on/off state of the

reference oscillators, which provides for shutting down a faulty

reference or for keeping a redundant reference turned off until

needed. The general configuration of the AD9574 is set via a

group of resistors that establish the desired PPRx states.

Although Figure 24 shows XOs with differential outputs, single-

ended XOs can be substituted by connecting the XO output to

the REFx_P pin and a 0.1 nF capacitor from the REFx_N pin to

GND.

REFERENCE

MONITOR

AD9574

PFD/

VCO

PPR CONTROL

×1/×2

REF0_P

REF0_N

REF1_P

REF1_N

MCLK_P

MCLK_N

REF_ACT

REF_SW

REF_FHI

REF_FLO

REF_SEL

REFMON

OUT0_N

OUT0_P

OUT1_N

OUT1_P

OUT2_N

OUT2_P

OUT3_N

OUT3_P

OUT4_N

OUT4_P

OUT5_N

OUT5_P

OUT6_N

OUT6_P

LDO_BYP

1nF

470nF

STABLE

REFERENCE

FPGA

ON/OFF

CONTROL

PROGRAMMING

RESISTORS

3.3V

Figure 24. Dual Oscillator Reference Input Application Diagram

AD9574 Datasheet(PDF) 30 Page - Analog Devices

AD9574 Datasheet(HTML) 30 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

Datasheet Download

Link URL