AN3433 Datasheet, PDF (1/34 Pages) STMicroelectronics – Optimizing wakeup time and power consumption in CR95HF and STRFNFCA devices

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.
February 2012
Doc ID 019046 Rev 2
1/34
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