ST-PLC-AFE datasheet(31/58 Pages) STMICROELECTRONICS

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ST-PLC-AFE

Powering the device and resetting the SPI and registers

Powering the device and resetting the SPI and

registers

7.1

Turning the device on and off

The ENABLE input pin (EN) allows the device to be turned on and off.

When EN is set to zero, all internal consumptions are reduced to a minimum, the SPI

interface is ready to receive messages from the microcontroller, and all internal registers

keep their value. Consequently, EN does not reset the IC. Using the SPI interface when the

IC is powered down, allows the system to be preprogrammed.

When the EN pin is high (1), the ST-PLC-AFE device operates normally.

By default, the PD_SPI bit is set to 0 (which means that all internal blocks of the device are

activated). To turn off the device using the registers, the PD_SPI must be set to 1. Then, all

internal blocks are turned off. The SPI interface is still active for microcontroller

communication and all registers keep their value without any resets.

7.2

Resetting the internal registers

The internal registers are reset by setting the RST_SPI bit in the Enable register to 1. By

doing this, all internal registers are set to their default values and the SPI interface performs

an auto-reset.

When the analog power supply, AVDD, increases from zero to its final value, an internal

power-on-reset (POR) occurs. All digital registers are reset when AVDD crosses the voltage

window 1.6 V to 2.4 V.

7.3

Resetting the SPI

The SPI is reset using the high state of the input pin nCS.

ST-PLC-AFE Fiches technique(PDF) 31 Page - STMicroelectronics