User Manual

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Rev. 4702D–RKE–02/04

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 (ATA5756) and 32 (ATA5757) Blocks for 13 MHz Crystal Frequencies and

for Low XTO Start-up Times

• Modulation Scheme ASK/FSK with Internal FSK Switch

• Up to 20 kBaud Manchester Coding, Up to 40 kBaud 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

• Supply Voltage 2.0 V to 3.6 V in Operation Temperature Range of -40°C to 125°C

• ESD Protection at all Pins (4 kV HBM)

• Small Package MSOP10

Benefits

• Low Parasitic FSK Switch Integrated

• Very Short and Reproducable Time to Transmit Typically <0.85 ms

• 13.125 MHz/13.56 MHz Crystals Give Opportunity for Small Package Sizes

Description

The ATA5756/ATA5757 is a PLL transmitter IC which has been developed for the

demands of RF low-cost transmission systems at data rates up to 20 kBaud Manches-

ter coding and 40 kBaud NRZ coding. The transmitting frequency range is 313 MHz to

317 MHz (ATA5756) and 432 MHz to 448 MHz (ATA5757), repectively. 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 (TPM) and for Passive Entry Go applications.

Figure 1. System Block Diagram

Demod.

IF Amp

LNA VCO

PLL XTO

Control

U3741B/

U3745B/

T5743/

T5744/

1...3

µC

Power

amp.

XTO

VCO

PLL

ATA5756/

ATA5757

Antenna Antenna

UHF ASK/FSK

TPM and Remote control

transmitter

UHF ASK/FSK

Remote control receiver

Encoder

ATARx9x

1 Li cell

Keys

UHF ASK/FSK

Transmitter

ATA5756

ATA5757

Preliminary

Summary of content (19 pages)

PAGE 1
Features • PLL Transmitter IC with Single-ended Output • High Output Power (6 dBm) at 8.1 mA (315 MHz) and 8.
PAGE 2
Pin Configuration Figure 2. Pinning MSOP10 CLK 1 10 ENABLE ASK 2 9 GND FSK 3 8 VS ANT2 4 7 XTO1 ANT1 5 6 XTO2 ATA5756 ATA5757 Pin Description Pin 1 Symbol CLK Function Configuration VS Clock output signal for the microcontroller. The clock output frequency is set by the crystal to fXTAL/8. The CLK output stays Low in powerdown mode and after enabling of the PLL. The CLK output switches on if the oscillation amplitude of the crystal has reached a certain level.
PAGE 3
ATA5756/ATA5757 [Preliminary] Pin Description Pin Symbol 4 ANT2 Function Configuration Emitter of antenna output stage ANT1 5 ANT1 Open collector antenna output ANT2 6 XTO2 Diode switch, used for FSK modulation 210 µA (FSK < 0.25V) AND (ENABLE > 1.7V) XTO2 VS 1.5k 7 XTO1 Connection for crystal VS 1.
PAGE 4
Figure 3. Block Diagram ATA5756 / ATA5757 Power up/down CLK EN f 1 ENABLE 10 8 f 24/ 32 ASK GND 2 9 OR PFD FSK VS 3 8 CP Ampl. OK XTO1 ANT2 4 XTO 7 LF EN ANT1 5 XTO2 VCO PA 6 PLL 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 × fXTAL/32 × fXTAL for ATA5756/ATA5757. Thus, a 13.125 MHz/13.56 MHz crystal is needed for a 315 MHz/433.92 MHz transmitter.
PAGE 5
ATA5756/ATA5757 [Preliminary] The power amplifier is an open-collector output delivering a current pulse which is nearly independent from the load impedance and can therefore be controlled via the connected load impedance. This output configuration enables a simple matching to any kind of antenna or to 50 Ω. A high power efficiency for the power amplifier results if an optimized load impedance of Z Load, opt = 380 Ω + j340 Ω (ATA5756) at 315 MHz and Z Load, opt = 280 Ω + j310 Ω (ATA5757) at 433.
PAGE 6
Transmission with ENABLE = open ASK Mode The ATA5756/ATA5757 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.
PAGE 7
ATA5756/ATA5757 [Preliminary] Transmission with ENABLE = High FSK Mode The ATA5756/ATA5757 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.
PAGE 8
Figure 7. Timing ASK Mode with ENABLE Connected to the Microcontroller ∆TXTO > 250 µs ENABLE FSK ASK CLK Power-down Accuracy of Frequency Deviation Power-up, Power-up, PA on PA off (High) (Low) Power-up, PA off Power-down 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.
PAGE 9
ATA5756/ATA5757 [Preliminary] 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 CStray.
PAGE 10
Output power measurement can be done with the circuit as shown in Figure 9. Please note that the component values must be changed to compensate the individual board parasitics until the ATA5756/ATA5757 has the right load impedance. Also, the damping of the cable used to measure the output power must be calibrated. Figure 9. Output Power Measurement ATA5756/ATA5757 VS C1 = 1n ~ L1 = 68 nH/ 39 nH Power meter Z = 50 Ω Z Lopt C2 = 2.2 pF/1.
PAGE 11
ATA5756/ATA5757 [Preliminary] Application Circuits For the supply voltage blocking capacitor C3, a value of 68 nF/X7R is recommended (see Figure 10 on page 12 and Figure 11 on page 13). C1 and C2 are used to match the loop antenna to the power amplifier. For C2, two capacitors in series should be used to achieve a better tolerance value and to enable it to realize ZLoad,opt by using capacitors with standard values.
PAGE 12
Figure 10. ASK Application Circuit BPXY S1 S2 VDD ATARx9x 1 VS VSS BPXY 20 BPXY OSC1 BPXY 7 ATA5756/ATA5757 Power up/down CLK f 1 ENABLE EN 10 8 f 24/ 32 ASK GND 2 9 OR C3 PFD FSK VS 3 8 CP C2 VS Ampl.
PAGE 13
ATA5756/ATA5757 [Preliminary] Figure 11. FSK Application Circuit BPXY S1 S2 VDD ATARx9x 1 VS VSS BPXY 20 BPXY OSC1 BPXY 7 ATA5756/ATA5757 Power up/down CLK 1 ENABLE EN f 10 8 f 24/ 32 ASK GND 9 2 OR C3 PFD FSK VS 3 8 CP C2 VS Ampl.
PAGE 14
Figure 12. ESD Protection Circuit VS ANT1 CLK ASK FSK XTO2 ANT2 XTO1 ENABLE GND Absolute Maximum Ratings Parameters Symbol Minimum Maximum Unit Supply voltage VS 5 V Power dissipation Ptot 100 mW Junction temperature Tj 150 °C Storage temperature Tstg -55 125 °C Ambient temperature Tamb1 -55 125 °C Ambient temperature in power-down mode for 15 minutes without damage with VS ≤3.2 V VENABLE < 0.25 V or ENABLE is open, VASK < 0.25 V, VFSK < 0.
PAGE 15
ATA5756/ATA5757 [Preliminary] Electrical Characteristics VS = 2.0 V to 3.6 V, Tamb = -40°C to 125°C unless otherwise specified. Typical values are given at VS = 3.0 V and Tamb = 25°C. All parameters are referred to GND (Pin 9). CM = 4.37 fF, C0 = 1.3 pF, CLNOM = 18 pF, C4 = 10 pF, C5 = 15 pF and RS ≤60 Ω Parameters Test Conditions Supply current, power-down mode VENABLE < 0.25 V or ENABLE is open, VASK < 0.25 V, VFSK < 0.
PAGE 16
Electrical Characteristics (Continued) VS = 2.0 V to 3.6 V, Tamb = -40°C to 125°C unless otherwise specified. Typical values are given at VS = 3.0 V and Tamb = 25°C. All parameters are referred to GND (Pin 9). CM = 4.37 fF, C0 = 1.3 pF, CLNOM = 18 pF, C4 = 10 pF, C5 = 15 pF and RS ≤60 Ω Parameters Test Conditions Symbol Min. Typ. Max. Unit Imaginary part of XTO1 Impedance in stady state oscillation Since pulling P is P = -IMXTO × CM × π × fXTO ∆fXTO can be calculated out of IMXTO with CM = 4.
PAGE 17
ATA5756/ATA5757 [Preliminary] Electrical Characteristics (Continued) VS = 2.0 V to 3.6 V, Tamb = -40°C to 125°C unless otherwise specified. Typical values are given at VS = 3.0 V and Tamb = 25°C. All parameters are referred to GND (Pin 9). CM = 4.37 fF, C0 = 1.
PAGE 18
Ordering Information Extended Type Number Package Remarks ATA5756-6DQ MSOP10 – ATA5757-6DQ MSOP10 – Package Information MSOP10 18 ATA5756/ATA5757 [Preliminary] 4702D–RKE–02/04
PAGE 19
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.