ATAB8402 Atmel, ATAB8402 Datasheet - Page 7

• Manufacturer Part Number: ATAB8402
• Description: BOARD DEMO 433MHZ RF TRANSMITTER
• Manufacturer: Atmel
• Type: Transmitterr

Specifications of ATAB8402

• Frequency: 433MHz
• Wireless Frequency: 315 MHz
• Modulation: ASK, FSK
• For Use With/related Products: ATA8402
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

2.3
Figure 2-7.
9115A–INDCO–01/08
The Setting of the Transmitter
V
C
S
1
XTAL
GND
Typical Application Schematic
VS
EN
BPXY
VSS
VDD
ATARx9x
OSC1
BPXY
BPXY
BPXY
a) ASK mode
Figure 2-6 on page 6
metal shielding is used. These types of crystals generally have four pads. The two ground pads
of the crystal must be connected to the board's ground plane properly. The connection between
the crystal and the pin XTO must be kept short. If the clock signal generated by the transmitter is
needed for the microprocessor, the trace between the pin CLK and the microprocessor pin must
be as short as possible. The layout in
the printed inductor as found on the demo board. The discrete inductor needs less space than
the printed one.
Notes:
In a practical application, there are different supply voltages on the board, for example for the
microprocessor and for the transmitter. The different traces from the battery must be separated
and decoupled to the ground.
Figure 2-7
If ENABLE = Low and PA_ENABLE = Low, the circuit is in standby mode. To start the crystal
oscillator (XTO), the pin ENABLE must be switched on. At the same time the Phase Locked
Loop (PLL) and the Clock Driver are active. To activate the power amplifier, the pin PA_ENABLE
must be set to high. After switching the pin ENABLE on, both the XTO circuit and the PLL need
a maximum of 1 ms to reach a stable condition. Therefore, the application software has to wait
at least 1 ms before switching the power amplifier on.
PA_EN
ANT1
ANT2
CLK
V
Choke
1. L1 is the RF choke
2. Cd1 is the decoupling capacitor near the battery
3. Cd2 is the decoupling capacitor for the transmitter's power supply
4. Cd3 is the capacitor to bypass the high-frequency coupling from the power amplifier output
S
S2
S1
RF
shows the typical applications for the transmitters in ASK or FSK mode.
into the transmitter's power supply. This capacitor must be placed near to the RF choke.
shows an example of an ideal layout. In this example, a crystal with a
Figure 2-6
C
ATA8401/ATA8402/ATA8403
2
V
C
uses a discrete element as RF choke instead of
S
1
XTAL
GND
VS
EN
BPXY
B42/
T20
VSS
VDD
ATARx9x
b) FSK mode
OSC1
BPXY
BPXY
BPXY
PA_EN
ANT1
ANT2
CLK
V
Choke
S
S2
S1
RF
7