Features • • • • • • • • • • • • • • Programmable AVR® 8-bit Flash Microcontroller Transmitter IC Frequency: 315 MHz (ATA6285) and 433 MHz (ATA6286) Support ASK/FSK Modulation with Integrated FSK Switch 6 dBm Output Power with Typically 8.5 mA Active Current Consumption in Transmission Mode Low-power Microcontroller Requires Typically 0.6 µA Sleep Current with Active Interval Timer Interfaces for Simple Capacitive Sensors (2 pF to 6 pF) One Interface Can Be Configured for Motion Wake-up (3 pF to 5 pF) Typically 25 mbar ADC Resolution for Pressure Measurement with Dedicated Sensor Type Low-power Measurement Mode for Directly Connected Capacitive Sensors Typically 200 µA at 1 MHz System Clock Programmable 125 kHz Wake-up Receiver Channel with Typically 1.7 µA Current Consumption in Listing Mode 2V to 3.6V Operation Voltage for Single Li-cell Power Supply –40°C to +125°C Operation Temperature and –40°C to +150°C Storage Temperature Less then 10 External Passive Components QFN32 (5 mm × 5 mm) Package 1. Description ATA6285 and ATA6286 are highly integrated smart RF micro transmitter ICs for 315 MHz and 433 MHz, suited for ASK and FSK with typically 20 Kbits/s data rate in Manchester mode. The devices combine the functionality of the RF transmitter ICs ATA5756/ATA5757 with the programmable low-power AVR 8-bit Flash microcontroller in a single QFN32 package (5 mm × 5 mm). The ATA6285 and ATA6286 include a dedicated ADC interface for simple capacitive sensors as well as an on-chip temperature sensor. Three sensor interfaces are available for a capacitive range of 2 pF to 16 pF, where one channel can be configured as motion wake-up in the range of 3 pF to 5 pF. The ICs are suited for use in tire pressure monitoring (TPMS) sensor gauges in combination with external sensor devices. The programmable AVR 8-bit Flash microcontroller includes 8 Kbytes of in-system self-programmable Flash memory and an 320-Bytes EEPROM, thus allowing the system integrator to install field-programmable firmware to enable system flexibility on different platforms. ATA6285 and ATA6286 can be configured to guarantee extremely low power consumption in sleep mode and measurement mode. They also include a programmable 125 kHz wake-up receiver channel for extremely low current consumption in listening mode. The ICs are designed for use in applications with typically less then 10 passive components: one external crystal for the sensor gauge, several capacitors, a single LiMnO2 battery coin cell, a single-ended antenna for the data transmission and an LF ferrite coil for the wake-up channel. ATA6285 and ATA6286 support TPMS-specific low-current modes even with an active brown-out detection and an interval timer. TPMS Control and Transmitter IC ATA6285 ATA6286 Summary Preliminary NOTE: This is a summary document. The complete document is available under NDA. For more information, please contact your local Atmel sales office. 4958AS–AUTO–09/06 2. Overview 2.1 Application Figure 2-1. Tire Pressure Monitoring System (TPMS) VDD Battery XZ Motion sensor Pressure sensor 16 15 14 13 12 11 10 9 17 8 18 7 19 20 21 6 ATA6285/ ATA6286 5 4 22 3 23 2 24 1 25 26 27 28 29 30 31 32 *) ISP: RF loop antenna *) ISP interface In-System-Programmable Flash interface Crystal Frequency 13.56 MHz for 433 MHz application Crystal Frequency 13.125 MHz for 315 MHz application 2 ATA6285/ATA6286 [Preliminary] 4958AS–AUTO–09/06 ATA6285/ATA6286 [Preliminary] Block Diagram VSRF VCC PB7 (NSS) PB5 (SCK) ATA6285/ATA6286 Block Diagram (MCP) PB3 (MOSI) Figure 2-2. PB4 (MISO) 2.2 CLOCK LF1 LF2 LF Receiver 125 kHz ECIN1 SPI Oscillator Voltage monitor EEPROM XTO Clock management and monitoring S0 S1 S2 PC2 PC1 PC0 XTO1 XTO2 PLL Timer block Watchdog oscillator ASK AVR Core Sensor interface/ input multiplexer Watchdog timer FSK RF Transmitter VCO 2.3 GND PD7 (SDIN) PD1 (T3I) debugWIRE PD2 (INTO) PB6 PD0 (T2ICP) PB2 (T2I) PB1 (T3O) PB0 (T3ICP) IO Ports Flash Power Supervision POR/ BOD/ TSD and RESET Power amplifier ANT1 ANT2 GNDRF SRAM NRESET Temperature sensor Inter-die Bonding The ATA6285/ATA6286 are Smart RF Micro Transmitter ICs in MCP (Multi Chip Package) technology. Table 2-1 shows the internal assembly of the MCP. Table 2-1. Inter-die Connection Description of the MCP AVR – Pin ATA5756/ATA5757 – Pin PD3 (INT1) – External interrupt input 1 EN – Enable input PD4 (ECIN1) – External clock input 1 CLK – Clock output signal PD5 (T2O1) – Timer2 modulator output 1 ASK – Input signal PD6 (T2O2) – Timer2 modulator output 2 FSK – Input signal 3 4958AS–AUTO–09/06 Pin Configuration S2 XTO1 VSRF GND NRESET PB2 (T2I) XTO2 GND 18 7 PB7 (NSS) LF1 19 6 PB6 LF2 20 5 PB1 (T3O) VCC 21 4 ANT1 PC2 22 3 ANT2 PC1 23 2 PB5 (SCK) PC0 1 24 25 26 27 28 29 30 31 32 PB4 (MISO) PB3 (MOSI) PD2 (INTO) PD7 (SDIN) GND GND PB0 (T3ICP) ATA62857 ATA6286 Pin Description Pin Number Pin Name Alternate Function 1 Alternate Function 2 Function Comment 1 PB4 MISO PCINT4 SPI Port B4 2 PB5 SCK PCINT5 SPI Port B5 3 ANT2 – – RF-antenna 2. Emitter of antenna output stage RF pin 4 ANT1 – – RF-antenna 1. Open collector antenna output RF pin 5 PB1 T3O PCINT1 Timer3 output 6 PB6 – PCINT6 7 PB7 NSS PCINT7 SPI Port B7 8 XT02 – – Switch for FSK modulation RF pin Note: 4 GND 16 15 14 13 12 11 10 9 8 17 PD0 (T2ICP) Table 2-2. S0 Pinning QFN32 S1 Figure 2-3. PD1 (T3I) 2.4 Port B1 Port B6 9 PB2 T2I PCINT2 Timer2 external input clock Port B2 10 XT01 – – Connection for crystal RF pin 11 VS_RF – – Power supply voltage for RF RF pin 12 GND – – Power supply ground for RF RF pin 13 NRESET debugWIRE – Reset input/debugWIRE interface 14 GND – – Power supply ground 15 S0 – – Sensor input 0 – Pressure Sensor (Cap.) 16 S1 – – Sensor input 1 – X – Motion Sensor (Cap.) 17 S2 – – Sensor input 2 – Z - Motion Sensor (Cap.) 18 GND – – Power supply ground 1. Internal inter-die connection of the MCP ATA6285/ATA6286 [Preliminary] 4958AS–AUTO–09/06 ATA6285/ATA6286 [Preliminary] Table 2-2. Pin Description (Continued) Pin Number Pin Name Alternate Function 1 Alternate Function 2 Function 19 LF1 – – LF-receiver input 1 20 LF2 – – LF-receiver input 2 21 VCC – – Power supply voltage (VCC + AVCC) 22 PC2 – PCINT10 - Comment Port C2 23 PC1 CLKO PCINT9 System clock output Port C1 24 PC0 ECIN0 PCINT8 External Clock input 0 Port C1 25 PD0 T2ICP PCINT16 Timer2 external input capture Port D0 26 PD1 T3I PCINT17 Timer3 external input clock Port D1 27 PB0 T3ICP PCINT0 Timer3 external input capture Port B0 28 GND – – Power supply ground 29 GND – – Power supply ground Inter-die(1) PD3 INT1 PCINT19 External Interrupt 1 → Inter-die connection Port D2 Inter-die(1) PD4 ECIN1 PCINT20 External Clock input 1 → Inter-die connection Port D4 Inter-die(1) PD5 T2O1 PCINT21 Timer2 Modulator output 1 → Inter-die connection Port D5 Inter-die(1) PD6 T2O2 PCINT22 Timer2 Modulator output 2 → Inter-die connection Port D6 30 PD7 SDIN PCINT23 SSI –Serial Data Input Port D7 31 PD2 INT0 PCINT18 External interrupt input 0 Port D2 32 PB3 MOSI PCINT3 SPI Port B3 Note: 2.5 2.5.1 1. Internal inter-die connection of the MCP Pin Names VCC Supply voltage 2.5.2 GND Ground 2.5.3 Port B (PB7..0) Port B is a 5(8)-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The PB7, PB6 and PB2 ports are only used as internal I/O ports for inter-die connections. The Port B output buffers have symmetrical drive characteristics with both high sink and source current capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up resistors are activated. The Port B pins are tri-stated when a reset condition becomes active, even if the clock is not running. Port B also serves the functions of various special features of the ATmegaT. 5 4958AS–AUTO–09/06 2.5.4 Port C (PC2..0) Port C is a 3-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port C output buffers have symmetrical drive characteristics with both high sink and source current capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up resistors are activated. The Port C pins are tri-stated when a reset condition becomes active, even if the clock is not running. 2.5.5 Port D (PD7..0) Port D is a 7(1)-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The PD(6..3) pins are used as internal inter-die connection I/O ports. The Port D output buffers have symmetrical drive characteristics with both high sink and source current capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The Port D pins are tri-stated when a reset condition becomes active, even if the clock is not running. Port D also serves the functions of various special features of the ATmegaT. 2.5.6 NRESET Reset input. A low level on this pin for longer than the minimum pulse length will generate a reset, even if the clock is not running. Shorter pulses then defined minimum pulse length are not guaranteed to generate a reset. 2.5.7 LF (2..1) Input coil pins for the LF-Receiver. 2.5.8 S (2..0) Measuring input pins for external capacitance sensor elements. 2.5.9 ANT(2, 1) RF-Antenna pins. 2.5.10 XTO(0, 1) External crystal for the internal RF transmitter IC. 6 ATA6285/ATA6286 [Preliminary] 4958AS–AUTO–09/06 ATA6285/ATA6286 [Preliminary] 3. Low Power AVR 8-bit Microcontroller 3.1 Features • High Performance, Extremely Low Power AVR 8-bit Microcontroller • Advanced RISC Architecture • • • • 3.2 – 131 Powerful Instructions – 32 × 8 General Purpose Working Registers – Fully Static Operation – On-chip 2-cycle Multiplier Non-volatile Program and Data Memories – 8 Kbytes of In-system Self-programmable Flash – Optional Boot Code Section with Independent Lock Bits – 320 (256 + 64) Bytes EEPROM – 512 Bytes Internal SRAM – Programming Lock for Software Security Peripheral Features – Programmable Watchdog/Interval Timer with Separate, Internally Calibrated and Extremely Low-power Oscillator – Two 16-bit Timer/Counter with Compare Mode, Capture Mode, and On-chip Digital Data Modulator Circuitry – Integrated On-chip Temperature Sensor with Thermal Shutdown Function – Sensor Interface for External Pressure Sensor and XZ- Motion Sensor – Highly Sensitive 1D LF-receiver – Programmable Voltage Monitor – System Clock Management and Clock Monitoring – Master/Slave SPI Serial Interface – Integrated Debug-Wire-Interface – Interrupt and Wake-up on Pin Change Special Microcontroller Features – Power-on Reset and Programmable Brown-out Detection – Internal Calibrated RC Oscillator – External and Internal Interrupt Sources – Three Sleep Modes: Idle, Sensor Noise Reduction, and Power-down I/O and Package – 15 Programmable I/O Lines Overview The embedded core is an extremely low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the AVR core achieves throughputs approaching 1 MIPS per MHz allowing the designer to optimize power consumption versus processing speed. 7 4958AS–AUTO–09/06 3.3 Block Diagram Figure 3-1. Microcontroller Block Diagram Oscillator circuit Watchdog timer 0 Clock management and monitoring Watchdog oscillator EEPROM SRAM Power Supervision POR/ BOD/ TSD and RESET VCC GND RESET Flash debugWIRE AVR Core Program logic AVCC 16 bit T/ C2 12 bit T1 Sensor value processing AGND 8 16 bit T/ C3 Temperature sensor MUX and sensor input SPI LF receiver Voltage monitor PORT C (x) PORT B (x) PORT D (x) ATA6285/ATA6286 [Preliminary] 4958AS–AUTO–09/06 ATA6285/ATA6286 [Preliminary] The AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers. The embedded architecture provides the following features: 8K bytes of In-System Programmable Flash with Read-While-Write capabilities, 320 (256 + 64) bytes EEPROM, 512 bytes SRAM, 11(19) general purpose I/O lines, 32 general purpose working registers, On-chip Debugging support and programming, two flexible Timer/Counters with compare modes, internal and external interrupts, a sensor interface for external pressure sensor and Acceleration/Motion sensor, a programmable Watchdog Timer with internal calibrated Oscillator, an SPI serial port, and three software selectable power saving modes. The device is manufactured using Atmel®’s high density non-volatile memory technology. The On-chip ISP Flash allows the program memory to be reprogrammed In-System through an SPI serial interface, by a conventional non-volatile memory programmer, or by an On-chip Boot program running on the AVR core. The Boot program can use any interface to download the application program in the Application Flash memory. Software in the Boot Flash section will continue to run while the Application Flash section is updated, providing true Read-While-Write operation. By combining an 8-bit RISC CPU with In-System Self-Programmable Flash on a monolithic chip, the Atmel ATmegaT is a powerful microcontroller that provides a highly flexible and cost effective solution to many embedded control applications. The AVR is supported with a full suite of program and system development tools including: C Compilers, Macro Assemblers, Program Debugger/Simulators, In-Circuit Emulators, and Evaluation Kits. 9 4958AS–AUTO–09/06 4. UHF ASK/FSK Transmitter for ATA6285/ATA6286 4.1 Features • PLL Transmitter IC with Single-ended Output • High output Power (6 dBm) at 8.1 mA (315 MHz) and 8.5 mA (433 MHz) Typical Values • Divide by 24 (ATA6285) and 32 (ATA6286) Blocks for 13 MHz Crystal Frequencies and for Low XTO Start-up Times • Modulation Scheme ASK/FSK with Internal FSK Switch • Up to 20 Kbits/s Manchester Coding, Up to 40 Kbits/s NRZ Coding • Power-down Idle and Power-up Modes to Adjust Corresponding Current Consumption through ASK/FSK/Enable Input Pins • ENABLE Input for Parallel Usage of Controlling Pins in a 3-wire Bus System • CLK Output Switches ON if the Crystal Current Amplitude Has Reached 35% to 80% of its Final Value • Crystal Oscillator Time until CLK Output Is Activated, Typically 0.6 ms 4.2 Benefits • Low Parasitic FSK Switch Integrated • Very Short and Reproducible Time to Transmit Typically < 0.85 ms • 13.125 MHz/13.56 MHz Crystals Give Opportunity for Small Package Sizes 4.3 Description The ATA6285/ATA6286 is a PLL transmitter part which has been developed for the demands of RF low-cost transmission systems at data rates up to 20 Kbits/s Manchester coding and 40 Kbits/s NRZ coding. The transmitting frequency range is 313 MHz to 317 MHz (ATA6285) and 432 MHz to 448 MHz (ATA6286), respectively. It can be used in both FSK and ASK systems. Due to its shorten crystal oscillator settling time it is well suited for Tire Pressure Monitoring (TPMS) and for Passive Entry Go applications. Figure 4-1. System Block Diagram UHF ASK/FSK TPM UHF ASK/FSK Receiver 1 Li cell Transmitter Part of ATA6285/ATA6286 Keys Encoder ATARx9x Digital Control Logic PLL VCO Antenna Microcontroller Interface (LNA, Mixer, VCO, PLL, IF Filter, RSSI Amp., Demodulator) Power amp. 10 Microcontroller RF Receiver Antenna VCO Power Supply 4 to 8 XTO ATA6285/ATA6286 [Preliminary] 4958AS–AUTO–09/06 ATA6285/ATA6286 [Preliminary] 4.4 General Description This fully integrated PLL transmitter allows the design of simple, low-cost RF miniature transmitters for TPM and RKE applications. The VCO is locked to 24 × f X T A L /32 x f X T A L for ATA6285/ATA6286. Thus, a 13.125 MHz/13.56 MHz crystal is needed for a 315 MHz/ 433.92 MHz transmitter. All other PLL and VCO peripheral elements are integrated. The XTO is a series resonance (current mode) oscillator. Only one capacitor and a crystal connected in series to GND are needed as external elements in an ASK system. The internal FSK switch, together with a second capacitor, can be used for FSK modulation. The crystal oscillator needs typically 0.6 ms until the CLK output is activated if a crystal as defined in the electrical characteristics is used (e.g., TPM crystal). For most crystals used in RKE systems, a shorter time will result. The CLK output is switched on if the amplitude of the current flowing through the crystal has reached 35% to 80% of its final value. This is synchronized with the 1.64 MHz/1.69 MHz CLK output. As a result, the first period of the CLK output is always a full period. The PLL is then locked < 250 µs after CLK output activation. This means an additional wait time of ≥ 250 µs is necessary before the PA can be switched on and the data transmission can start. This results in a significantly lower time of about 0.85 ms between enabling the ATA6285/ATA6286 and the beginning of the data transmission which saves battery power especially in tire pressure monitoring systems. The power amplifier is an open-collector output delivering a current pulse which is nearly independent from the load impedance and therefore the output power can be controlled via the connected load impedance. This output configuration enables a simple matching to any kind of antenna or to 50Ω. A high power efficiency for the power amplifier results if an optimized load impedance of ZLoad, opt = 380Ω + j340Ω (ATA6285) at 315 MHz and ZLoad, opt = 280Ω + j310Ω (ATA6286) at 433.92 MHz is used at the 3V supply voltage. 4.5 Functional Description If ASK = Low, FSK = Low and ENABLE = open or Low, the circuit is in power-down mode consuming only a very small amount of current so that a lithium cell used as power supply can work for many years. If the ENABLE pin is left open, ENABLE is the logical OR operation of the ASK and FSK input pins. This means, the IC can be switched on by either the FSK of the ASK input. If the ENABLE pin is Low and ASK or FSK are High, the IC is in idle mode where the PLL, XTO and power amplifier are off and the microcontroller ports controlling the ASK and FSK inputs can be used to control other devices. This can help to save ports on the microcontroller in systems where other devices with 3-wire interface are used. With FSK = High and ASK = Low and ENABLE = open or High, the PLL and the XTO are switched on and the power amplifier is off. When the amplitude of the current through the crystal has reached 35% to 80% of its final amplitude, the CLK driver is automatically activated. The CLK output stays Low until the CLK driver has been activated. The driver is activated synchronously with the CLK output frequency, hence, the first pulse on the CLK output is a complete period. The PLL is then locked within < 250 µs after the CLK driver has been activated, and the transmitter is then ready for data transmission. 11 4958AS–AUTO–09/06 With ASK = High the power amplifier is switched on. This is used to perform the ASK modulation. During ASK modulation the IC is enabled with the FSK or the ENABLE pin. With FSK = Low the switch at pin XTO2 is closed, with FSK = High the switch is open. To achieve a faster start-up of the crystal oscillator, the FSK pin should be High during start-up of the XTO because the series resistance of the resonator seen from pin XTO1 is lower if the switch is off. The different modes of the ATA6285/ATA6286 are listed in Table 4-1. Table 4-1. 4.5.1 4.5.1.1 Transmitter Part ASK Pin FSK Pin ENABLE Pin Mode Low Low Low/open Power-down mode, FSK switch High Z Low Low High Power-up, PA off, FSK switch Low Z Low High High/open Power-up, PA off, FSK switch High Z High Low High/open Power-up, PA on, FSK switch Low Z High High High/open Power-up, PA on, FSK switch High Z Low/High High Low Idle mode, FSK switch High Z High Low/High Low Idle mode, FSK switch High Z Transmission with ENABLE = Open ASK Mode The ATA6285/ATA6286 is activated by ENABLE = open, FSK = High, ASK = Low. The microcontroller is then switched to external clocking. After typically 0.6 ms, the CLK driver is activated automatically (i.e., the microcontroller waits until the XTO and CLK are ready). After another time period of ≤ 250 µs, the PLL is locked and ready to transmit. The output power can then be modulated by means of pin ASK. After transmission, ASK is switched to Low and the microcontroller returns back to internal clocking. Then, the ATA6285/ATA6286 is switched to power-down mode with FSK = Low. Figure 4-2. Timing ASK Mode with ENABLE Open ∆TXTO > 250 µs FSK ASK CLK Power-down 12 Power-up, PA off Power-up, PA on (High) Power-up, PA off (Low) Power-down ATA6285/ATA6286 [Preliminary] 4958AS–AUTO–09/06 ATA6285/ATA6286 [Preliminary] 4.5.1.2 FSK Mode The ATA6285/ATA6286 is activated by FSK = High, ASK = Low. The microcontroller is then switched to external clocking. After typically 0.6 ms, the CLK driver is activated automatically (i.e., the microcontroller waits until the XTO and CLK are ready. After another time period of ≤ 250 µs, the PLL is locked and ready to transmit. The power amplifier is switched on with ASK = H. The ATA6285/ATA6286 is then ready for FSK modulation. The microcontroller starts to switch on and off the capacitor between the crystal load capacitor and GND by means of pin FSK, thus, changing the reference frequency of the PLL. IF FSK = L the output frequency is lower, if FSK = H output frequency is higher. After transmission, FSK stays High and ASK is switched to Low and the microcontroller returns back to internal clocking. Then, the ATA6285/ATA6286 is switched to power-down mode with FSK = Low. Figure 4-3. Timing FSK Mode with ENABLE Open ∆TXTO > 250 µs FSK ASK CLK Power-down 4.5.2 4.5.2.1 Power-up, PA off Power-up, Power-up, PA off PA on (fRF = High) (fRF = Low) Power-down Transmission with ENABLE = High FSK Mode The ATA6285/ATA6286 is activated by ENABLE = High, FSK = High and ASK = Low. The microcontroller is then switched to external clocking. After typically 0.6 ms, the CLK driver is activated automatically (i.e., the microcontroller waits until the XTO and CLK are ready). After another time period of ≤ 250 µs, the PLL is locked and ready to transmit. The power amplifier is switched on with ASK = H. The ATA6285/ATA6286 is then ready for FSK modulation. The microcontroller starts to switch on and off the capacitor between the crystal load capacitor and GND by means of pin FSK, thus, changing the reference frequency of the PLL. IF FSK = L the output frequency is lower, if FSK = H output frequency is higher. After transmission, ASK is switched to Low and the microcontroller returns back to internal clocking. Then, the ATA6285/ATA6286 is switched to power-down mode with ENABLE = Low and FSK = Low. 13 4958AS–AUTO–09/06 Figure 4-4. Timing FSK Mode with ENABLE Connected to the Microcontroller ∆TXTO > 250 µs ENABLE FSK ASK CLK Power-down 4.5.2.2 Power-up, PA off Power-up, Power-up, PA on PA off (fRF = High) (fRF = Low) Power-down ASK Mode The ATA6285/ATA6286 is activated by ENABLE = High, FSK = High and ASK = Low. After activation the microcontroller is switched to external clocking. After typically 0.6 ms, the CLK driver is activated automatically (the microcontroller waits until the XTO and CLK are ready). After another time period of ≤ 250 µs, the PLL is locked and ready to transmit. The output power can then be modulated by means of pin ASK. After transmission, ASK is switched to Low and the microcontroller returns back to internal clocking. Then, the ATA6285/ATA6286 is switched to power-down mode with ENABLE = Low and FSK = Low. Figure 4-5. Timing ASK Mode with ENABLE Connected to the Microcontroller ∆TXTO > 250 µs ENABLE FSK ASK CLK Power-down 14 Power-up, PA off Power-up, PA on (High) Power-up, PA off (Low) Power-down ATA6285/ATA6286 [Preliminary] 4958AS–AUTO–09/06 ATA6285/ATA6286 [Preliminary] 4.5.3 Accuracy of Frequency Deviation The accuracy of the frequency deviation using the XTAL pulling method is about ±20% if the following tolerances are considered. One important aspect is that the values of C0 and CM of typical crystals are strongly correlated which reduces the tolerance of the frequency deviation. Figure 4-6. Tolerances of Frequency Modulation VS CStray XTAL CM LM RS C0 Crystal equivalent circuit C4 C5 CSwitch Using a crystal with a motional capacitance of CM = 4.37 fF ±15%, a nominal load capacitance of CLNOM = 18 pF and a parallel capacitance of C 0 = 1.30 pF correlated with CM results in C0 = 297 × CM (the correlation has a tolerance of 10%, so C0 = 267 to 326 × CM). If using the internal FSK switch with CSwitch = 0.9 pF ±20% and estimated parasitics of CStray = 0.7 pF ±10%, the resulting C4 and C5 values are C4 = 10 pF ±1% and C5 = 15 pF ±1% for a nominal frequency deviation of ±19.3 kHz with worst case tolerances of ±15.8 kHz to ±23.2 kHz. 4.5.4 Accuracy of the Center Frequency The imaginary part of the impedance in large signal steady state oscillation IMXTO, seen into the pin 7 (XTO1), causes some additional frequency tolerances, due to pulling of the XTO oscillation frequency. These tolerances have to be added to the tolerances of the crystal itself (adjustment tolerance, temperature stability and ageing) and the influence to the center frequency due to tolerances of C4, C5, CSwitch and C Stray. The nominal value of IMXTO = 110Ω, C Switch and C Stray should be absorbed into the C4 and C5 values by using a crystal with known frequency and choosing C4 and C5, so that the XTO center frequency equals the crystal frequency, and the frequency deviation is as expected. Then, from the nominal value, the IMXTO has ±90Ω tolerances, using the pulling formula P = –IMXTO × CM × Pi × fXTO with fXTO = 13.56 MHz and CM = 4.4 fF an additional frequency tolerance of P = ±16.86 ppm results. If using crystals with other CM the additional frequency tolerance can be calculated in the same way. For example, a lower C M = 3.1 fF will reduce the frequency tolerance to 11.87 ppm, where a higher C M = 5.5 fF increases the tolerance to 21.07 ppm. 4.5.5 CLK Output An output CLK signal of 1.64 MHz (ATA6285 operating at 315 MHz) and 1.69 MHz (ATA6286 operating at 433.92 MHz) is provided for a connected microcontroller. The delivered signal is CMOS-compatible with a High and Low time of >125 ns if the load capacitance is lower than 20 pF. The CLK output is Low in power-down mode due to an internal pull-down resistor. After enabling the PLL and XTO the signal stays Low until the amplitude of the crystal oscillator has reached 35% to 80% of its amplitude. Then, the CLK output is activated synchronously with its output signal so that the first period of the CLK output signal is a full period. 15 4958AS–AUTO–09/06 4.5.5.1 4.5.6 Clock Pulse Take-over by Microcontroller The clock of the crystal oscillator can be used for clocking the microcontroller. Atmel’s ATARx9x microcontroller family provides the special feature of starting with an integrated RC oscillator to switch on the ATA6285/ATA6286 external clocking and to wait automatically until the CLK output of the ATA6285/ATA6286 is activated. After a time period of 250 µs the message can be sent with crystal accuracy. Output Matching and Power Setting The output power is set by the load impedance of the antenna. The maximum output power is achieved with a load impedance of Z Load, opt = 380Ω + j340Ω (ATA6286) at 315 MHz and ZLoad, opt = 280Ω + j310Ω (ATA6285) at 433.92 MHz. A low resistive path to VS is required to deliver the DC current. The power amplifier delivers a current pulse and the maximum output power is delivered to a resistive load if the 0.66 pF output capacitance of the power amplifier is compensated by the load impedance. At the ANT1 pin, the RF output amplitude is about VS – 0.5V. The load impedance is defined as the impedance seen from the ATA6285’s ANT1, ANT2 into the matching network. Do not mix up this large-signal load impedance with a small-signal input impedance delivered as an input characteristic of RF amplifiers. The latter is measured from the application into the IC instead of from the IC into the application for a power amplifier. The 0.66 pF output capacitance absorbed into the load impedance a real impedance of 684Ω (ATA6285) at 315 MHz and 623Ω (ATA6286) at 433.92 MHz should be measured with a network analyses at pin 5 (ANT1) with the ATA6285/ATA6286 soldered, an optimized antenna connected and the power amplifier switched off. Less output power is achieved by lowering the real parallel part where the parallel imaginary part should be kept constant. Lowering the real part of the load impedance also reduces the supply voltage dependency of the output power. Output power measurement can be done with the circuit as shown in Output Power Measurement. Please note that the component values must be changed to compensate the individual board parasitics until the ATA6285/ATA6286 has the right load impedance. Also, the damping of the cable used to measure the output power must be calibrated. Figure 4-7. Output Power Measurement ATA6285/ATA6286 VS C1 = 1 nF L1 = 68 nH/ 39 nH Z = 50Ω ANT1 ZLopt C2 = 2.2 pF/ 1.8 pF ANT2 16 Power meter Rin 50Ω ATA6285/ATA6286 [Preliminary] 4958AS–AUTO–09/06 ATA6285/ATA6286 [Preliminary] 5. Ordering Information Extended Type Number Package Frequency MOQ Remarks ATA6285-PNPW QFN32 315 MHz Packaging unit: 1,500 Taped and reeled ATA6286-PNPW QFN32 433 MHz Packaging unit: 1,500 Taped and reeled ATA6285-PNQW QFN32 315 MHz 6,000 Taped and reeled ATA6286-PNQW QFN32 433 MHz 6,000 Taped and reeled 6. Package Information Package: QFN_ 5 x 5_32L Exposed pad 3.6 x 3.6 Dimensions in mm Bottom Not indicated tolerances ±0.05 3.6±0.15 Top 32 25 32 1 24 1 17 17 8 Pin1 identification 5 Z 0.2 0.9±0.1 0.5 nom. 3.5 technical drawings according to DIN specifications Drawing-No.: 6.543-5124.01-4 Issue: 1; 28.11.05 9 0.4±0.1 Z 10:1 16 0.23±0.07 17 4958AS–AUTO–09/06 Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131, USA Tel: 1(408) 441-0311 Fax: 1(408) 487-2600 Regional Headquarters Europe Atmel Sarl Route des Arsenaux 41 Case Postale 80 CH-1705 Fribourg Switzerland Tel: (41) 26-426-5555 Fax: (41) 26-426-5500 Asia Room 1219 Chinachem Golden Plaza 77 Mody Road Tsimshatsui East Kowloon Hong Kong Tel: (852) 2721-9778 Fax: (852) 2722-1369 Japan 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 Japan Tel: (81) 3-3523-3551 Fax: (81) 3-3523-7581 Atmel Operations Memory 2325 Orchard Parkway San Jose, CA 95131, USA Tel: 1(408) 441-0311 Fax: 1(408) 436-4314 RF/Automotive Theresienstrasse 2 Postfach 3535 74025 Heilbronn, Germany Tel: (49) 71-31-67-0 Fax: (49) 71-31-67-2340 Microcontrollers 2325 Orchard Parkway San Jose, CA 95131, USA Tel: 1(408) 441-0311 Fax: 1(408) 436-4314 La Chantrerie BP 70602 44306 Nantes Cedex 3, France Tel: (33) 2-40-18-18-18 Fax: (33) 2-40-18-19-60 ASIC/ASSP/Smart Cards 1150 East Cheyenne Mtn. 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