2.4.1 Typical Application Circuit with External Microcontroller

Figure 2-3. Typical Application Circuit with External Microcontroller

The preceding figure illustrates a typical application circuit with an external host microcontroller running from a 3V voltage regulator. The pin PB4 (PWRON) is directly connected to VS and the ATA8210/15 enters the IDLEMode after power-on. In this configuration, the ATA8210/15 can work autonomously, and the microcontroller stays powered down to keep current consumption low while remaining sensitive to RF telegrams.

To achieve a low current in IDLEMode, configure the ATA8210/15 in the EEPROM to work with the RC oscillator. The user can configure the ATA8210/15 for autonomous multi channel and multi application PollingMode. If the ATA8210/15 receives an appropriate RF message, the event on pin 28 (EVENT) notifies the external microcontroller. Until this event, the ATA8210/15 periodically switches to RXMode, checks the different services and channels configured in the EEPROM and returns to power-down while the external host microcontroller is still in Deep Sleep mode to keep average current low. After the detection of a valid RF message, buffer the valid RF message inside of the ATA8210/15 to enable a microcontroller wake-up and retrieval of buffered data.

The RF_IN is matched to SPDT_RX by absorbing the parasitics of the SPDT switch into the matching network, hence the SPDT_ANT is a 50Ω RX port.

Use the fractional-N PLL and an external crystal to fix the RX frequency of the ATA8210/15. Accurate load capacitors for this crystal are integrated to reduce the system part count and cost. Only three supply-blocking capacitors are needed to decouple the different supply voltages: AVCC, DVCC and VS of the ATA8210/15. The exposed die pad is the RF and analog ground of the ATA8210/15. It is directly connected to AGND via a fused lead. For applications operating in the 868.3 MHz or 915 MHz frequency bands, supply a High-Band RF input, RFIN_HB, and use the RFIN_HB instead of RFIN_LB. The user can control the ATA8210/15 using specific SPI commands via the SPI interface and an internal EEPROM for application-specific configurations.