AD9557SLASHPCBZ datasheet(54/92 Pages) AD

54 / 92 page

AD9557

Data Sheet

Rev. A | Page 54 of 92

PIN PROGRAM FUNCTION DESCRIPTION

The AD9557 supports both hard pin and soft pin program

function, with the on-chip ROM containing the predefined

configurations. When a pin program function is enabled and

initiated, the selected, predefined configuration is transferred

from the ROM to the corresponding registers to configure the

part into the desired state.

OVERVIEW OF ON-CHIP ROM FEATURES

Input/Output Frequency Translation Configuration

The AD9557 has one on-chip ROM that contains a total of 256

different input-output frequency translation configurations for

independent selection of 16 input frequencies and 16 output

frequencies. Each input/output frequency translation

configuration assumes that all input frequencies are the same

and all the output frequencies are the same. Each configuration

reprograms the following registers/parameters:

•

Reference input period register

•

Reference divider R register

•

Digital PLL feedback divider register (Fractional Part FRAC1,

Modulus Part MOD1 and Integer Part N1) free run

•

Tuning word register

•

Output PLL feedback divider N2 register

•

RF divider register

•

Clock distribution channel divider register

All configurations are set to support one single system clock

frequency as 786.432 MHz (16× the default 49.152 MHz system

clock reference frequency).

Four Different System Clock PLL Configurations

•

REF = 49.152 MHz XO (×2 on, N = 8)

•

REF = 49.152 MHz XTAL (×2 on, N = 8)

•

REF = 24.756 MHz XTAL (×2 on, N = 16)

•

REF = 98.304 MHz XO (×2 off, N = 8)

Four Different DPLL Loop Bandwidths

•

1 Hz, 10 Hz, 50 Hz, 100 Hz

DPLL Phase Margin

•

Normal phase margin (70°)

•

High phase margin (88.5°)

The ROM also contains an APLL VCO calibration bit. This bit

is used to program Register 0x0405[0] (from 0) to 1 to generate

a low-high transition to automatically initiate APLL VCO cal.

Table 32. Preset Input Frequencies for Hard Pin and Soft Pin Programming

Hard Pin Program

PINCONTROL = High

Soft Pin Program

PINCONTROL = Low,

Freq ID

Frequency (MHz)

Frequency Description

M0 Pin

0.008

8 kHz

19.44

19.44 MHz

25 MHz

Table 33. Preset Output Frequencies for Hard Pin and Soft Pin Programming

Hard Pin Program

PINCONTROL = High

Soft Pin Program

PINCONTROL = Low,

Freq ID

Frequency (MHz)

Frequency Description

M3 Pin

M2 Pin

M1 Pin

19.44

19.44 MHz

25 MHz

125

125 MHz

156.7071

156.25 MHz × 1027/1024

622.08

622.08 MHz

625

625 MHz

644.53125

625 MHz × 33/32

657.421875

657.421875 MHz

660.184152

657.421875 MHz × 239/238

666.5143

622.08 MHz × 255/238

669.3266

622.08 MHz × 255/237

672.1627

622.08 MHz × 255/236

690.5692

644.53125 MHz × 255/238

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