February 2012

Doc ID 019046 Rev 2

1/34

AN3433

Application note

Optimizing wakeup time and power consumption

in CR95HF and STRFNFCA devices

Introduction

This document describes several tips for application engineers to effectively manage CR95HF and

STRFNFCA operating states and modes to define an adapted wakeup condition to return to its Active

state to start communication with the external world in order to reduce power consumption.

The CR95HF and STRFNFCA have 2 main functional domains. In the first one, Active mode, the devices

are able to communicate with a host using one of the serial interfaces (UART or SPI) or with RFID tags

using its RF capabilities. In this mode, the device consumption is only a few milliamps, and when it emits

RF signals, its field consumption becomes tens of milliamps. In the second domain, Wait for Event (WFE)

mode, the device remains quiescent while waiting for an external event. In this mode, a very low level of

power consumption (only a few microamps) may be achieved.

An application engineer is able to manage the wakeup conditions in order to adapt his strategy to

optimize wakeup time or system power consumption.

This application note will provide guidelines for choosing the best implementation.

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