Rainbow Electronics ATA6286 User Manual
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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
4.5.2
Transmission with ENABLE = High
4.5.2.1
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 acti-
vated 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.
Power-down
Power-down
Power-up,
PA off
Power-up,
PA on
(f
RF
= High)
Power-up,
PA off
(f
RF
= Low)
FSK
ASK
CLK
∆
T
XTO
> 250 µs