TH7122 Datasheet, PDF (20/44 Pages) Melexis Microelectronic Systems – 27 to 930MHz FSK/FM/ASK Transceiver

TH7122
27 to 930MHz
FSK/FM/ASK Transceiver
Due to the static CMOS design, the SCI consumes virtually no current and it can be programmed in active as
well as in standby mode.
If the transceiver is set from standby mode to any of the active modes (idle, receive, transmit), the SCI set-
tings remain the same as previously set in one of the active modes, unless new settings are done on the SCI
while entering into an active mode.
Invalid
data MSB
SDTA
bit 23
bit 22
Invalid
LSB
data
bit 1
bit 0
SCLK
t_CS
SDEN
t_CH
t_CWL t_CWH
t_ES
Fig. 13: Serial Data Input Timing
t_EW t_EH
5 Register Description
As shown in the previous section there are four control words which stipulate the operation of the whole chip.
In Stand-alone User Mode SUM the intrinsic default values with respect to the applied levels at pins FS0 and
FS1 lay down the configuration of the transceiver. In Programmable User Mode (PUM) the register settings
can be changed via 3-wire interface SCI. The default settings which vary with the desired operating fre-
quency depend on the voltage levels at the frequency selection pins FS0 and FS1 before entering the PUM.
Table 5.1.1 shows the default register settings of different frequency selections. It should be noted that the
channel frequency listed below will be achieved with a crystal frequency of 7.1505 MHz. The following table
depicts an overview of the register configuration of the TH7122.
39010 07122
Rev. 008
Page 20 of 44
Data Sheet
June/07