STW81101ATR datasheet(33/48 Pages) STMICROELECTRONICS

Nome de Peças	STW81101ATR

Descrição Electrónicos	Multi-band RF frequency synthesizer with integrated VCOs

PDF	48 Pages

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Fabricante Electrônico	STMICROELECTRONICS [STMicroelectronics]

Página de início	http://www.st.com

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33 / 48 page

STW81101

SPI digital interface

33/48

SPI digital interface

7.1

General features

The SPI digital interface is selected by hardware connection of the pin #21 (DBUS_SEL) to

3.3V.

The STW81101 IC is programmed by means of a high-speed serial-to-parallel interface with

write option only. The 3-wire bus can be clocked at a frequency as high as 100MHz to allow

fast programming of the registers containing the data for RF IC configuration.

The chip is programmed through serial words with a full length of 26 bits. The first 2 MSBs

represent the address of the registers, and the 24 LSBs represent the value of the registers.

Each data bit is stored in the internal shift register on the rising edge of the CLOCK signal.

The outputs of the selected register are sent to the device on the rising edge of the LOAD

signal.

Figure 26.

SPI input and output bit order

Last bit sent

(LSB)0

25(MSB)

LOAD #4

Address

decoder

DATA

LOAD

Reg.#4

Reg.#1

Reg.#0

D23 (MSB)

D0 (LSB)

STW81101ATR Folha de dados(PDF) 33 Page - STMicroelectronics