ATA5771-DK1 Atmel, ATA5771-DK1 Datasheet - Page 8

• Manufacturer Part Number: ATA5771-DK1
• Description: BOARD XMITTER FOR ATA5771 868MHZ
• Manufacturer: Atmel
• Type: Transmitterr

Specifications of ATA5771-DK1

• Frequency: 868MHz
• Maximum Frequency: 868 MHz
• Supply Voltage (max): 4 V
• Supply Voltage (min): 2 V
• Supply Current: 8.5 mA
• Product: RF Development Tools
• For Use With/related Products: ATA5771
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3.1
3.2
3.3
8
Frequency Generation
ASK Transmission
FSK Transmission
Atmel ATA5771/73/74
In Atmel ATA5773 and Atmel ATA5774 the VCO is locked to 32 times crystal frequency hence
the following crystal is needed
The VCO of ATA5771 is locked to 64 times crystal frequency therefore the necessary crystal
frequency is
Due to the high integration the PLL and VCO peripheral elements are integrated.
The XTO is a series resonance oscillator that only one capacitor together with a crystal con-
nected in series to GND are needed as external elements. Until the PLL and clock output is
stable the following time can be expected
Therefore, a time delay of
tion of pin ENABLE and switching on the pin PA_ENABLE must be implemented in the
software.
The ASK modulation will performed by switching the power amplifier on and of due to the data
to be transmitted. The transmitter’s XTO and PLL are activated by setting the pin ENABLE to
HIGH. Between the activation of the pin ENABLE and the pin PA_ENABLE minimum 3 ms
time delay must be taken into account for the application with ATA5773, whereas a minimum
1 ms time delay for an application using ATA5771 or ATA5774. After the mentioned time delay
the generated clock frequency by the RF transmitter can be used as reference for the data
generation of the microcontroller block.
The transmitter’s XTO and PLL are activated by setting the pin ENABLE to HIGH. Like the
ASK transmission a defined time delay must be taken into account between the activation of
the pin ENABLE and the pin PA_ENABLE. After this time delay the clock frequency can be
used as reference for the data rate generation and the data transmission using FSK modula-
tion is ready. For this purpose an additional capacitor to the crystal’s load capacitor will be
switched between the high impedance and ground due to the data rate. Thus the reference
frequency, which is crystal frequency, of the RF transmitter will be modulated. This results also
in the transmitted spectrum. It is important that the switching element must have a defined low
parasitic capacitance.
The accuracy of the frequency deviation with XTAL pulling method is about ±25% when the
following tolerances are considered.
• 9.8438MHz for 315MHz application
• 13.56MHz for 433.92MHz application
• 13.5672MHz for 868.3MHz application
• 14.2969MHz for 915MHz application
• 3ms for ATA5773
• 1ms for ATA5771 and ATA5774
3 ms for ATA5773 and
1 ms for ATA5771/74 between activa-
9137E–RKE–12/10