STW81101 datasheet(29/42 Pages) STMICROELECTRONICS

Part #	STW81101

Description	Multi-band RF frequency synthesizer with integrated VCOs

PDF	42 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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29 / 42 page

STW81101

SPI digital interface

29/42

SPI digital interface

6.1

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-wires 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 programming of the chip is done through serial words with whole length of 26 bits. The

first 2 MSB represent the address of the registers. The others 24 LSB represent the value of

the registers.

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

On the rising edge of the LOAD signal the outputs of the selected register are sent to the

device.

Figure 22.

SPI input and output bit order

STW81101 Datasheet(PDF) 29 Page - STMicroelectronics