EVB72006 Datasheet, PDF (6/12 Pages) Melexis Microelectronic Systems – 315MHz FSK/ASK Transmitter Evaluation Board Description

EVB72006
315MHz FSK/ASK Transmitter
Evaluation Board Description
2.8 Mode Control Logic
The mode control logic allows two different
modes of operation as listed in the following
table. The mode control pin EN is pulled-down
internally. This guarantees that the whole circuit
is shut down if this pin is left floating.
EN
Mode
Description
0
TX standby
TX disabled
1
TX active
TX / CKOUT
CKOUT active
enabled
2.9 Clock Output
The clock output CKOUT is CMOS-compatible and can be used to drive a microcontroller. The frequency of
the clock can be changed by the clock divider control signal CKDIV, that can be selected according to the
following table. A capacitor at pin CKOUT can be used to control the clock voltage swing and the spurious
emission.
CKDIV
0
1
Clock divider ratio
4
16
Clock frequency / f_c=4315 MHz
2.46 MHz
615 kHz
2.10 Timing Diagrams
After enabling the transmitter by the EN signal, the power amplifier remains inactive for the time t_on, the
transmitter start-up time. The crystal oscillator starts oscillation and the PLL locks to the desired output fre-
quency within the time duration t_on. After successful PLL lock, the LOCK signal turns on the power amplifier,
and then the RF carrier can be FSK or ASK modulated.
high
EN
low
high
LOCK
low
high
FSKDTA
low
high
EN
low
high
LOCK
low
high
PSEL
low
RF carrier
t
t
t _on
t _on
Fig. 5: Timing diagrams for FSK and ASK modulation
For more detailed information, please refer to the latest TH72006 data sheet revision.
39012 72006 01
Rev. 004
Page 6 of 12
EVB Description
Dec/07