Datasheet

AFE4490

SBAS602F –DECEMBER 2012–REVISED OCTOBER 2013

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After power-up, the internal registers must be initialized to the default values. This initialization can be done in

one of two ways:

• Through a hardware reset by applying a low-going pulse on the RESET pin, or

• By applying a software reset. Using the serial interface, set SW_RESET (bit D3 in register 00h) high. This

setting initializes the internal registers to the default values and then self-resets to '0'. In this case, the RESET

pin is kept high (inactive).

AFE SPI Interface Design Considerations

Note that when the AFE4490 is deselected, the SPISOMI, CLKOUT, ADC_RDY, PD_ALM, LED_ALM, and

DIAG_END digital output pins do not enter a 3-state mode. This condition, therefore, must be taken into account

when connecting multiple devices to the SPI port and for power-management considerations. In order to avoid

loading the SPI bus when multiple devices are connected, the DIGOUT_TRISTATE register bit must be to '1'

whenever the AFE SPI is inactive.

AFE REGISTER MAP

The AFE consists of a set of registers that can be used to configure it, such as receiver timings, I-V amplifier

settings, transmit LED currents, and so forth. The registers and their contents are listed in Table 5. These

registers can be accessed using the AFE SPI interface.

Product Folder Links: AFE4490