SI5356A Datasheet, PDF(12/29 Page) Silicon Laboratories – IC PROGRAMMABLE, ANY-FREQUENCY 1–200 MHZ, QUAD FREQUENCY 8-OUTPUT CLOCK GENERATOR

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SI5356A Datasheet, PDF (12/29 Pages) Silicon Laboratories – IC PROGRAMMABLE, ANY-FREQUENCY 1–200 MHZ, QUAD FREQUENCY 8-OUTPUT CLOCK GENERATOR

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Si5356A

3.5.1. Ordering a Custom NVM Configuration

The Si5356 is orderable with a factory-programmed

custom NVM configuration. This is the simplest way of

using the Si5356 since it generates the desired output

frequencies at power-up or after a power-on reset

(POR). This default configuration can be reconfigured in

RAM through the I2C interface after power-up (see

â3.5.2. Creating a New Configuration for RAMâ).

The first step in ordering a custom device is generating

an NVM file which defines the input and output clock

frequencies and signal formats. This is easily done

using the NVMï®Save for Factory Programming... menu

option in ClockBuilder Desktop. (See "3.1.1.

ClockBuilderâ¢ Desktop Software" on page 9.) This

Windows based software allows the user to generate an

NVM file, which is used by the factory to manufacture

custom parts. Each custom part is marked with a unique

part number identifying the specific configuration (e.g.,

Si5356A-A00100-GM).

Consult your local sales representative for more details

on ordering a custom Si5356.

3.5.2. Creating a New Configuration for RAM

Any Si5356 device can be configured by writing to

registers in RAM through the I2C interface. A non-

factory programmed device must be configured in this

manner.

When creating a custom RAM configuration, use the

following procedure:

1. Create a device configuration (register map) using

ClockBuilder Desktop (v3.0 or later; see "3.1.1.

ClockBuilderâ¢ Desktop Software" on page 9) or

manually using the equations in âAN565: Configuring

the Si5356Aâ.

a. Configure the frequency plan.

b. Configure the output driver format and supply

voltage.

c. Configure initial phase offset (if desired).

d. Configure spread spectrum (if desired).

2. Save the configuration using the Options > Save

File, or create the register contents by the

conversions listed in AN565.

At this point, the new configuration can be written to the

device RAM according to the instructions in â3.5.3.

Writing a Custom Configuration to RAMâ.

3.5.3. Writing a Custom Configuration to RAM

Writing a new configuration (register map) to the RAM

consists of pausing the LOL state-machine, writing new

values to the IC accounting for the write-allowed mask

given in AN565, validating the input clock or crystal,

locking the PLL to the input with the new configuration,

restarting the LOL state-machine, and calibrating the

VCO for robust operation across temperature. The flow

chart in Figure 5 on page 13 enumerates the details:

Note: The write-allowed mask specifies which bits must be

read and modified before writing the entire register

byte (a.k.a. read-modify-write). âAN428: Jump Start: In-

System, Flash-Based Programming for Silicon Labsâ

Timing Productsâ illustrates the procedure defined in

Section 3.5.2 with ANSI C code.

Rev. 1.3

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