System Control

The LM4934 is controlled via either a three wire SPI or a two wire I

MODE is cleared the device is in I

operating mode, interfaces, data converters, mixers and amplifiers. The LM4934 is controlled by writing 8 bit data into a series

of write-only registers, the device is always a slave for both type of interfaces.

THREE WIRE, SPI INTERFACE (MODE = 1)

Three Wire Mode Write Bus Transaction

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When the part is configured as an SPI device and the enable (ENB) line is lowered the serial data on SDI is clocked in on the

rising edge of the SCK line. The protocol used is 16bit, MSB first. The upper 8 bits (15:8) are used to select an address within

the device, the lower 8 bits (7:0) contain the updated data for this register.

TWO WIRE I

Two Wire Mode Write Bus Transaction

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Three Wire Mode Write Bus Timing

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FIGURE 3. Three Wire Mode Write Bus

Two Wire Mode Write Bus Timing

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FIGURE 4. Two Wire Mode Write Bus

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