AN2452 datasheet(4/21 Pages) STMICROELECTRONICS

Part #	AN2452

Description	STW8110x evaluation board and graphical user interface

PDF	21 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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Software

AN2452

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Figure 1.

Main form

Swallow counter A: 5-bit counter.

VCO calibrator:

–

Last calibration Fvco: contains the last calibration data (VCO and frequency of

calibration).

–

Calibrator ON/OFF.

–

The maximum allowed Fpfd during calibration is 1 MHz. If Fpfd > 1 MHz, the device

is programmed in two steps:

a) Device is programmed forcing calibration with the maximum Fpfd ≤1MHz

(Fpfd = Fref / R ≤1 MHz ==> R ≥ Fref / 10

6).

b) Device is programmed with the desired Fpfd.

Example with Fref = 76.8 MHz:

Desired values:

- Fpfd = 1200 kHz

- R = Fref / Fpfd = 64

Forced values:

- R' =

⎡Fref / 106⎤ = ⎡76.8⎤ = 77

- F'pfd = Fref / R' = 997.403 kHz

Device programming in two steps:

a) Device is programmed with Fpfd = 997.403 kHz and Calibrator ON.

b) Device is programmed with Fpfd = 1200 kHz and Calibrator OFF.

AN2452 Datasheet(PDF) 4 Page - STMicroelectronics