ATA8401_14 ATMEL

Document overview

  • Manufacturer or author: Provided By digicamel.com
  • PDF pages: 13

Technical content

Features

  • Integrated PLL loop filter
  • ESD protection (3kV HBM/150V MM)
  • High output power (8.0dBm) with low supply current (9.0mA)
  • Modulation scheme ASK/FSK
  • FSK modulation is achieved by connecting an additional capacitor between the XTAL load capacitor and the open drain output of the modulating microcontroller
  • Easy to design-in due to excellent isolation of the PLL from the PA and power supply
  • Single Li-cell for power supply
  • Supply voltage 2.0V to 4.0V in the temperature range of –40°C to +85°C
  • Package TSSOP8L
  • Single-ended antenna output with high efficient power amplifier
  • CLK output for clocking the microcontroller
  • One-chip solution with minimum external circuitry

Applications

  • Industrial/aftermarket remote keyless entry systems
  • Alarm, telemetering, and energy metering systems
  • Remote control systems for consumer and industrial markets
  • Access control systems
  • Home automation
  • Home entertainment
  • Toys ATA8401 UHF ASK/FSK Industrial Transmitter DATASHEET

ATA8401 [DATASHEET] 4984B–INDCO–07/14 1. Description The Atmel® ATA8401 is a PLL transmitter IC, which has been developed for the demands of RF low-cost transmission systems for industrial applications at data rates up to 50kBaud ASK and 32kBaud FSK modulation scheme. The transmitting frequency range is 300MHz to 350MHz. It can be used in both FSK and ASK systems. Figure 1-1. System Block Diagram Micro- controller PLL UHF ASK/FSK Remote control receiver UHF ASK/FSK Remote control transmitter Atmel ATA8401 Atmel ATA8201 ATA8203 LNA VCO PLL XTO LNA VCO Antenna Demod IF Amp Control 1 to 3 Encoder ATARx9x XTO

1 Li cell

3ATA8401 [DATASHEET] 4984B–INDCO–07/14 2. Pin Configuration Figure 2-1. Pinning TSSOP8L Table 2-1. Pin Description Pin Symbol Function Configuration

1 CLK

Clock output signal for microcontroller The clock output frequency is set by the crystal to f XTAL/4

2 PA_ENABLE Switches on power amplifier used for

Emitter of antenna output stage Open collector antenna output ENABLE VS GND ATA8401 XTAL CLK PA_ENABLE ANT2 ANT1 100Ω 100Ω CLK VS 20μA UREF = 1.1VPA_ENABLE 50kΩ ANT1 ANT2

ATA8401 [DATASHEET] 4984B–INDCO–07/14 Figure 2-2. Block Diagram

5 XTAL Connection for crystal

6 VS Supply voltage See ESD protection circuitry (see Figure 4-5 on page 8)

7 GND Ground See ESD protection circuitry (see Figure 4-5 on page 8)

8 ENABLE Enable input

Table 2-1. Pin Description (Continued) Pin Symbol Function Configuration 1.5kΩ 1.2kΩ 182μA XTAL VS VS 200kΩENABLE Atmel ATA8401 CP Power up/down PDF XTAL VS GND ENABLE ANT1 ANT2 PA_ENABLE CLK f LF PA VCO PLL XTO f

5ATA8401 [DATASHEET] 4984B–INDCO–07/14 3. General Description This fully integrated PLL transmitter allows particularly simple, low-cost RF miniature transmitters to be assembled. The VCO is locked to 32 fXTAL, and therefore a 9.8438MHz crystal is needed for a 315MHz transmitter. All other PLL and VCO peripheral elements are integrated. The XTO is a series resonance oscillator so that only one capacitor together with a crystal connected in series to GND are needed as external elements. The crystal oscillator together with the PLL typically needs < 3ms until the PLL is locked and the CLK output is stable. There is a wait time of ≥ 3ms until the CLK is used for the microcontroller and the PA is switched on. The power amplifier is an open-collector output delivering a current pulse, which is nearly independent from the load impedance. The delivered output power is therefore controllable via the connected load impedance. This output configuration enables a simple matching to any kind of antenna or to 50Ω. A high power efficiency of η =P out/(IS,PA VS) of 40% for the power amplifier results when an optimized load impedance of ZLoad =( 2 5 5+j 1 9 2 )Ω is used at 3V supply voltage. 4. Functional Description If ENABLE = L and the PA_ENABLE = L, the circuit is in standby mode, consuming only a very small amount of current, so that a lithium cell used as power supply can work for several years. With ENABLE = H the XTO, PLL, and the CLK driver are switched on. If PA_ENABLE remains L, only the PLL and the XTO are running, and the CLK signal is delivered to the microcontroller. The VCO locks to 32 times the XTO frequency. With ENABLE = H and PA_ENABLE = H the PLL, XTO, CLK driver, and the power amplifier are on. The power amplifier can be switched on and off with PA_ENABLE. This is used to perform the ASK modulation.

4.1 ASK Transmission

The Atmel® ATA8401 is activated by ENABLE = H. PA_ENABLE must remain L for typically≥ 3 ms, then the CLK signal can be taken to clock the microcontroller and the output power can be modulated by means of the PA_ENABLE pin. After transmission, PA_ENABLE is switched to L and the microcontroller switches back to internal clocking. The Atmel ATA8401 is switched back to standby mode with ENABLE = L.

4.2 FSK Transmission

The Atmel ATA8401 is activated by ENABLE = H. PA_ENABLE must remain L for typically ≥ 3ms, then the CLK signal can be taken to clock the microcontroller, and the power amplifier is switched on with PA_ENABLE = H. The chip is then ready for FSK modulation. The microcontroller starts to switch on and off the capacitor between the XTAL load capacitor and GND with an open-drain output port, thus changing the reference frequency of the PLL. If the switch is closed, the output frequency is lower than if the switch is open. After transmission, PA_ENABLE is switched to L, and the microcontroller switches back to internal clocking. The Atmel ATA8401 is switched back to standby mode with ENABLE = L. The accuracy of the frequency deviation with XTAL pulling method is about ±25% when the following tolerances are considered. Figure 4-1. Tolerances of Frequency Modulation Using C4 = 8.2pF ±5%, C5 = 10pF ±5%, a switch port with CSwitch = 3pF ±10%, stray capacitances on each side of the crystal of CStray1 =C Stray2 = 1pF ±10%, a parallel capacitance of the crystal of C0 = 3.2pF ±10%, and a crystal with CM =1 3f F± 1 0 % , typically results in an FSK deviation of ±21.5kHz with worst case tolerances of ±16.25kHz to ±28.01kHz. RS LM C4 CM VS XTAL Crystal equivalent circuit C0 C5 CSwitch CStray1 CStray2

ATA8401 [DATASHEET] 4984B–INDCO–07/14

4.3 CLK Output

An output CLK signal is provided for a connected microcontroller. The delivered signal is CMOS compatible if the load capacitance is lower than 10pF.

4.3.1 Clock Pulse Take-over

The clock of the crystal oscillator can be used for clocking the microcontroller. A special feature of Atmel®’s AVR® is that it starts with an integrated RC-oscillator to switch on the Atmel ATA8401 with ENABLE = H, and after 3ms assumes the clock signal of the transmission IC, so that the message can be sent with crystal accuracy.

4.3.2 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 ZLoad,opt =( 2 5 5+j 1 9 2 )Ω. There must be a low resistive path to VS to deliver the DC current. The delivered current pulse of the power amplifier is 9mA. The maximum output power is delivered to a resistive load of 400Ω if the 1.0pF output capacitance of the power amplifier is compensated by the load impedance. An optimum load impedance of: ZLoad = 400Ω || j/(2 ×π 1.0pF) = (255 + j192)Ω thus results for the maximum output power of 8 dBm. The load impedance is defined as the impedance seen from the Atmel ATA8401’s ANT1, ANT2 into the matching network. Do not confuse this large signal load impedance with a small signal input impedance delivered as input characteristic of RF amplifiers and measured from the application into the IC instead of from the IC into the application for a power amplifier. Less output power is achieved by lowering the real parallel part of 400Ω where the parallel imaginary part should be kept constant. Output power measurement can be done with the circuit shown in Figure 4-2. Note that the component values must be changed to compensate for the individual board parasitics until the Atmel ATA8401 has the right load impedance Z Load,opt =( 2 5 5+j 1 9 2 )Ω. Also the damping of the cable used to measure the output power must be calibrated out. Figure 4-2. Output Power Measurement at f = 315MHz Note: For 345MHz C 2 has to be changed to 2.7pF

4.4 Application Circuit

A value of C3 = 68nF/X7R is recommended for the supply-voltage blocking capacitor C3 (see Figure 4-3 on page 7 and Figure 4-4 on page 8). C1 and C2 are used to match the loop antenna to the power amplifier where C1 typically is 22pF/NP0 and C2 is 10.8pF/NP0 (18pF + 27pF in series). For C2, two capacitors in series should be used to achieve a better tolerance value and to have the possibility of realizing the ZLoad,opt using standard valued capacitors. C1, together with the pins of Atmel ATA8401 and the PCB board wires, forms a series resonance loop that suppresses the 1st harmonic. Therefore, the position of C1 on the PCB is important. Normally the best suppression is achieved when C1 is placed as close as possible to the pins ANT1 and ANT2. The loop antenna should not exceed a width of 1.5mm, otherwise the Q-factor of the loop antenna is too high. L1 ([50nH to 100nH) can be printed on PCB. C4 should be selected so that the XTO runs on the load resonance frequency of the crystal. Normally, a 15pF load-capacitance crystal results in a value of 12pF. 1nF 3.3pF 56nH VS Rin ANT2 ANT1 ZLopt Power meter 50Ω Z = 50Ω

7ATA8401 [DATASHEET] 4984B–INDCO–07/14 Figure 4-3. ASK Application Circuit Atmel AVR (ATtiny) Atmel ATA8401 CP Power up/down PDF VDD BPXY VSS VS XTAL XTAL VS VS VS GND ENABLE ANT1 Loop Antenna C2 ANT2 PA_ENABLE OSC1 BPXY BPXY BPXYS1 CLK f LF PA VCO PLL XTO f

9ATA8401 [DATASHEET] 4984B–INDCO–07/14 5. Absolute Maximum Ratings Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Parameters Symbol Minimum Maximum Unit Supply voltage VS 5 V Power dissipation Ptot 100 mW Junction temperature Tj 150 °C Storage temperature Tstg –55 +85 °C Ambient temperature Tamb –55 +85 °C Input voltage VmaxPA_ENABLE –0.3 (VS + 0.3)(1) V 6. Thermal Resistance Parameters Symbol Value Unit Junction ambient RthJA 170 K/W 7. Electrical Characteristics VS = 2.0V to 4.0V, Tamb = 25°C unless otherwise specified. Typical values are given at VS = 3.0V and Tamb = 25°C. All parameters are referred to GND (pin 7). Parameters Test Conditions Symbol Min. Typ. Max. Unit Supply current Power down, VENABLE < 0.25V, –40°C to 85°C VPA-ENABLE < 0.25V, 25°C (100% correlation tested) IS_Off <1 0 350 nA nA Supply current Power up, PA off, VS = 3V, VENABLE >1 . 7 V , VPA-ENABLE <0 . 2 5 V IS 3.7 4.8 mA Supply current Power up, VS = 3.0V, VENABLE >1 . 7 V , VPA-ENABLE >1 . 7 V IS_Transmit 9 11.6 mA Output power VS =3 . 0 V , Tamb = 25°C, f = 315 MHz, ZLoad = (255 + j192)W PRef 6.0 8.0 10.5 dBm Output power variation for the full temperature range Tamb = 25°C, VS = 3.0V VS = 2.0V ΔPRef ΔPRef –1.5 –4.0 dB dB Output power variation for the full temperature range Tamb = 25°C, VS = 3.0V VS = 2.0V, POut = PRef + ΔPRef ΔPRef ΔPRef –2.0 –4.5 dB dB Achievable output-power range Selectable by load impedance POut_typ 0 8.0 dBm Spurious emission fCLK = f0/128 Load capacitance at pin CLK = 10pF fO ±1 × fCLK fO ±4 × fCLK Other spurious are lower –55 –52 dBc dBc Note: 1. If V S is higher than 3.6V, the maximum voltage will be reduced to 3.6V.

ATA8401 [DATASHEET] 4984B–INDCO–07/14 Oscillator frequency XTO (= phase comparator frequency) fXTO = f0/32 fXTAL = resonant frequency of the XTAL, CM ≤ 10fF, load capacitance selected accordingly T amb = 25°C fXTO fXTAL ppm PLL loop bandwidth 250 kHz Phase noise of phase comparator Referred to fPC = fXT0, 25kHz distance to carrier –116 –110 dBc/Hz In-loop phase noise PLL 25kHz distance to carrier –86 –80 dBc/Hz Phase noise VCO At 1MHz At 36MHz –94 –125 –90 –121 dBc/Hz dBc/Hz Frequency range of VCO fVCO 300 350 MHz Clock output frequency (CMOS microcontroller compatible) f0/128 MHz Voltage swing at pin CLK CLoad ≤ 10pF V0h V0l VS × 0.8 VS × 0.2 V V Series resonance R of the crystal Rs 110 Ω Capacitive load at pin XT0 7 pF FSK modulation frequency rate Duty cycle of the modulation signal = 50% 0 32 kHz ASK modulation frequency rate Duty cycle of the modulation signal = 50% 0 50 kHz ENABLE input Low level input voltage High level input voltage Input current high VIl VIh IIn 1.7 0.25 V V µA PA_ENABLE input Low level input voltage High level input voltage Input current high VIl VIh IIn 1.7 0.25 VS (1) V V µA 7. Electrical Characteristics (Continued) VS = 2.0V to 4.0V, Tamb = 25°C unless otherwise specified. Typical values are given at VS = 3.0V and Tamb = 25°C. All parameters are referred to GND (pin 7). Parameters Test Conditions Symbol Min. Typ. Max. Unit Note: 1. If V S is higher than 3.6V, the maximum voltage will be reduced to 3.6V.

11ATA8401 [DATASHEET] 4984B–INDCO–07/14 9. Package Information 8. Ordering Information Extended Type Number Package MOQ Remarks ATA8401C-6AQY TSSOP8L 5000 pcs Taped and reeled, Pb-free Package Drawing Contact: packagedrawings@atmel.com GPC DRAWING NO. REV. TITLE 6.543-5083.01-4 2 03/15/04 Package: TSSOP 8L 3±0.1 0.85±0.05 0.1±0.05 specifications according to DIN technical drawings Dimensions in mm 0.65 nom. 3 x 0.65 = 1.95 nom. 0.31-0.07 +0.06 0.15 -0.02+0.05 1-0.15 +0.05 3.8±0.3 4.9±0.1 3±0.1

ATA8401 [DATASHEET] 4984B–INDCO–07/14 10. Revision History Please note that the following page numbers referred to in this section refer to the specific revision mentioned, not to this document. Revision No. History 4984G-INDCO-07/14 • Put datasheet in the latest template 4984F-INDCO-08/12 • Features on page 1 changed 4984E-INDCO-03/12

  • Features on page 1 changed
  • Section 8 “Ordering Information” on page 11 changed 4984D-INDCO-12/10
  • Section 1 “Description” on page 1 changed
  • Section 7 “Electrical Characteristics” on page 10 changed 4984C-INDCO-04/09
  • Section 4.3.1 “Clock Pulse Take-over” on page 5 changed
  • Figure 4-3 “ASK Application Circuit” on page 7 changed
  • Figure 4-4 “FSK Application Circuit” on page 8 changed 4984B-INDCO-11/08
  • Put datasheet in the newest template
  • Section 4.3.1 “Clock Pulse Take-over” on page 5 changed

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