AN3433 datasheet(6/34 Pages) STMICROELECTRONICS

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Management of CR95HF or STRFNFCA activity

AN3433

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Doc ID 019046 Rev 2

Management of CR95HF or STRFNFCA activity

2.1

Overview of operating modes

The CR95HF and STRFNFCA have 2 operating modes: Wait for Event (WFE) and Active. In

Active mode, the device communicates actively with a tag or an external host (MCU). WFE

mode includes four low consumption states: Power-up, Hibernate, Sleep and Tag Detector.

The CR95HF or STRFNFCA can switch from one mode to another.

Hibernate, Sleep and Tag Detector states can only be activated by a command from the

external host (MCU). As soon as any of these three states are activated, the device can no

longer communicate with the external host. It can only be woken up.

The behavior of the device in 'Tag Detector' state is defined by the Idle command.

Table 3.

CR95HF or STRFNFCA operating modes and states

Mode

State

Description

Wait For

Event

(WFE)

Power-up

This mode is accessible directly after POR.

Low level on IRQ_IN pin (longer than 10 µs) is the only wakeup

source. LFO (low-frequency oscillator) is running in this state.

Hibernate

Lowest power consumption state. The device has to be woken-up in

order to communicate. Low level on IRQ_IN pin (longer than 10 µs) is

the only wakeup source.

Sleep

Low power consumption state. Wakeup source is configurable:

–Timer

–IRQ_IN pin

– SPI_SS pin

LFO (low-frequency oscillator) is running in this state.

Tag Detector

Low power consumption state with tag detection. Wakeup source is

configurable:

–Timer

–IRQ_IN pin

– SPI_SS pin

– Tag detector

LFO (low-frequency oscillator) is running in this state.

Active

Power-up

This mode is accessible directly after POR.

Low level on IRQ_IN pin (longer than 10 µs) is the only wakeup

source. LFO (low-frequency oscillator) is running in this state.

Hibernate

Lowest power consumption state. The device has to be woken-up in

order to communicate. Low level on IRQ_IN pin (longer than 10 µs) is

the only wakeup source.

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