ATA8520-GHQW

ATA8520 Single-Chip SIGFOX RF Transmitter DATASHEET Features ● Fully integrated, single-chip RF transmitter (SIGFOX™ compliant) ● System-on-chip solution including SIGFOX related protocol handling for modem operation ● AVR® microcontroller core with embedded firmware, SIGFOX, protocol stack and ID/PAC ● Supports uplink operation, i.e. transmit data telegram to SIGFOX base stations ● Operating frequency range: 868.0MHz to 868.6MHz ● Low current consumption: 32.7mA during telegram transmit with +14.5dBm TX output power ● Typical OFF mode current: 5nA (maximum 600nA at VS = +3.6V and T = +85°C) ● Data rate: 100bit/s with DBPSK modulation ● SPI interface for TX data access and transmitter configuration ● Event signal indicates the status of the IC to an external microcontroller ● Power-up (typical 10ms OFF mode -> IDLE mode) ● Supply voltage ranges 1.9V to 3.6V and 2.4V to 5.5V (SIGFOX compliant supply range 3V±5% and 3.3V to 5.5V) ● Temperature range –40°C to +85°C ● ESD protection at all pins (±4kV HBM, ±200V MM, ±750V FCDM) ● Small 55mm QFN32 package/pitch 0.5mm Applications SIGFOX compatible modem for long-range, low-power and low-cost applications using the SIGFOX network ● Home and building automation ● Alarm and security systems ● Smart environment and industrial ● Smart parking ● Tracking ● Metering 9372H-INDCO-11/15 1. General Description 1.1 Introduction The Atmel® ATA8520 is a highly integrated, low-power RF transmitter with an integrated AVR® microcontroller for applications using the wide area SIGFOX™ network The Atmel ATA8520 is partitioned into three sections: an RF front end, a digital baseband and the low-power 8-bit AVR microcontroller. The product is designed for the ISM frequency band in the range of 868.0MHz to 868.6MHz. The external part count is kept to a minimum due to the very high level of integration in this device. By combining outstanding RF performance with highly sophisticated baseband signal processing, robust wireless communication can be easily achieved. The transmit path uses a closed loop fractional-N modulator. The SPI interface enables external control and device configuration. 1.2 System Overview Figure 1-1. Circuit Overview AVCC VS DVCC Supply and Reset PLL SIGFOX Protocol Stack RF_OUT Firmware DSP Peripherals TX ID and PAC CPU RF Frontend DATA BUS XTO Port B Port C PB[7..0] (SPI) PC[5..0] XTAL Figure 1-1 shows an overview of the main functional blocks of the Atmel ATA8520. External control of the Atmel ATA8520 is performed through the SPI pins SCK, MOSI, MISO, and NSS. The functionality of the device is defined by the internal firmware and processed by the AVR. SPI commands are used to control the device and to start the data telegram transmission. The end of the telegram transmission is signaled to an external microcontroller on pin 28 (PB6/EVENT). It is important to note that all PWRON and NPWRON pins (PC1..5, PB4, PB7) are active in OFF mode. This means that even if the Atmel ATA8520 is in OFF mode and the DVCC voltage is switched off, the power management circuitry within the Atmel ATA8520 biases these pins with VS. The AVR microcontroller ports can be used as button inputs, LED drivers, EVENT pin, general purpose digital inputs, or wake-up inputs, etc. Functionality of these ports is already implemented in the firmware. 2 ATA8520 [DATASHEET] 9372H–INDCO–11/15 Pinning NC NC NC AGND PB7 PB6 PB5 PB4 PB3 Figure 1-2. Pin Diagram 32 31 30 29 28 27 26 25 1 NC 2 NC 3 exposed die pad Atmel ATA8520 24 PB2 23 PB1 22 PB0 21 DGND 6 19 PC5 RF_OUT 7 18 PC4 VS_PA 8 17 PC3 9 10 11 12 13 14 15 16 PC2 NC PC1 DVCC PC0 20 VS 5 AVCC NC XTAL2 4 XTAL1 NC NC 1.3 Note: The exposed die pad is connected to the internal die. Table 1-1. Pin Description Pin No. Pin Name Type 1 NC Connected to GND 2 NC Connected to GND 3 NC Connected to GND 4 NC Connected to GND 5 NC Leave open Description 6 NC 7 RF_OUT Analog Connected to GND Power amplifier output 8 VS_PA Analog Power amplifier supply. 3V supply: connect to VS. 5V supply: leave open. Use SPI command “Write System Configuration” (0x11) to enable 5V supply mode 9 NC – 10 XTAL1 Analog Crystal oscillator pin 1 (input) 11 XTAL2 Analog Crystal oscillator pin 2 (output) 12 AVCC Analog RF front-end supply regulator output 13 VS Analog Main supply voltage input 14 PC0 Digital Main : NRESET 15 PC1 Digital Main Alternate : AVR Port C1 : NPWRON1 16 PC2 Digital Main Alternate : AVR Port C2 : NPWRON2 17 PC3 Digital Main Alternate : AVR Port C3 : NPWRON3 Connected to GND ATA8520 [DATASHEET] 9372H–INDCO–11/15 3 Table 1-1. Pin Description (Continued) Pin No. Pin Name Type Description 18 PC4 Digital Main Alternate : AVR Port C4 : NPWRON4 19 PC5 Digital Main Alternate : AVR Port C5 : NPWRON5 20 DVCC – Digital supply voltage regulator output 21 DGND – Digital ground 22 PB0 Digital Main :-- 23 PB1 Digital Main : SCK 24 PB2 Digital Main : MOSI (SPI master out Slave in) 25 PB3 Digital Main : MISO (SPI master in Slave out) 26 PB4 Digital Main : PWRON 27 PB5 Digital Main : NSS 28 PB6 Digital Main : EVENT 29 PB7 Digital Main Alternate : TX active : NPWRON6 30 AGND – Analog ground 31 NC – Connected to GND NC – Connected to GND GND – Ground/backplane on exposed die pad 32 4 ATA8520 [DATASHEET] 9372H–INDCO–11/15 1.4 Applications This section provides application examples for the two supply modes for the Atmel® ATA8520 device. In addition the recommended PCB design and layout is described to achieve the SIGFOX™ certification. 3V Application Example Figure 1-3. 3V Application with External Microcontroller IRQ NSS MISO NC 25 PB3 26 PB4 27 PB5 PB7 1 28 PB6 29 AGND NC 30 NC 31 32 24 23 22 NC PB0 Atmel ATA8520 4 NC 21 DGND 20 5 NC PC5 RF_OUT PC4 18 VS_PA PC3 17 C2 9 10 11 12 13 14 15 C5 PC2 PC1 PC0 VS AVCC XTAL2 7 8 C1 NC 19 XTAL1 L1 Microcontroller DVCC 6 RF Filter SCK PB1 NC 3 C6 MOSI PB2 2 NC 1.4.1 16 Wake/Monitor Q1 C3 C4 VS = 3V VDD Supply Figure 1-3 shows a typical application circuit with an external host microcontroller operating from a 3V lithium cell. The Atmel ATA8520 stays in OFFMode until NPWRON1 (PC1) is used to wake it up. In OFFMode the Atmel ATA8520 draws typically less than 5nA at 25°C. In OFFMode all Atmel ATA8520 AVR® ports PB0..PB7 and PC0..PC5 are switched to input. PC0..PC5 and PB7 have internal pull-up resistors ensuring that the voltage at these ports is VS. PB0..PB6 are tri-state inputs and require additional consideration. PB1, PB2, and PB5 have defined voltages since they are connected to the output of the external microcontroller. PB4 is connected to ground to avoid unwanted power-ups. PB0, PB3 and PB6 do not require external circuitry since the internal circuit avoids transverse currents in OFFMode. The external microcontroller has to tolerate the floating inputs. Otherwise additional pull-down resistors are required on these floating lines. Typically, the Atmel ATA8520 wake-up is done by pulling NPWRON1 (pin 15) to ground. RF_OUT is matched with C1/L1 for 50 antenna connection. The RF filter is required to suppress unwanted side and spurious emissions. The design of this filter depends on the final PCB and system layout and is subject to SIGFOX and ETSI certification procedures. Together with the fractional-N PLL within the Atmel ATA8520, an external crystal is used to fix the Tx frequency. Accurate load capacitors for this crystal are integrated to reduce the system part count and cost. Only four supply blocking capacitors are needed to decouple the different supply voltages AVCC, DVCC, VS, and VS_PA of the Atmel ATA8520. The exposed die pad is the RF and analog ground of the Atmel ATA8520. It is connected directly to AGND via a fused lead. The Atmel ATA8520 is controlled using specific SPI commands via the SPI interface. ATA8520 [DATASHEET] 9372H–INDCO–11/15 5 1.4.2 5V Application Example In addition to the 3V supply mode the device can be used with a 3.3V to 5.5V supply voltage as shown in Figure 1-4. This requires to remove the connection between VS and VS_PA (pin 8) and to enable the internal LDO regulator. The 5V mode can be enabled using the SPI command “Write System Configuration” (0x11) followed by a system reset to enable these settings (the 5V mode can only be used with firmware revision ≥V1.0. Firmware revisions