TRF6900
SINGLE-CHIP RF TRANSCEIVER
SLAS213C – SEPTEMBER 1999 – REVISED MAY 2000
PRINCIPLES OF OPERATION
Table 3. Miscellaneous Control Register Description
INITIAL SETTINGS
AFTER POWER-UP
BIT
NUMBER
SYMBOL WORD
DESCRIPTION
LOCATION OF BITS
DEFAULT DEFAULT
STATE
VALUE
All zeroes
All zeroes
All zeroes
0b
DDS_0
DDS_1
DEV
A-word
B-word
D-word
C-word
[21:0]
[21:0]
[20:13]
[15]
22
22
8
DDS frequency setting in Mode0
DDS frequency setting in Mode1
FSK frequency deviation register
Zero
Zero
Zero
SLCTL
1
Slicer mode select bit
0 : hold mode
Hold
mode
1 : learning mode
APLL
C-word
[20:18]
3
Acceleration factor for the frequency acquisition aid charge pump
Zero
000b
A2
0
A1
0
A0
0
: 1
0
0
0
0
1
1
1
0
1
: 20
: 40
: 60
:
1
1
1
: 140
NPLL
MM
C-word
C-word
[17]
[16]
1
1
PLL divider ratio
0 : 256
256
0b
0b
1 : 512
Modulation mode select. Sets the behavior of pin TX_DATA to
FSK
FSK data input.
0 : FSK/FM
mode
1 : Do not use
operating modes
Tables 4 and 5 illustrate operating modes and transmit frequencies as set by the STDBY, MODE, and TX_DATA
terminals used in conjunction with the DDS frequency settings.
Table 4. Transmitting Data in FSK Mode (MM bit set to 0)
TERMINAL
TRANSMIT FREQUENCY
STDBY
MODE
TX_DATA
24
=ƒ × N × (DDS_0)/2
out ref
1
1
1
0
0
1
0
1
0
ƒ
ƒ
ƒ
24
24
=ƒ × N × (DDS_0 + 4 × DEV)/2
out ref
24
= ƒ × N × (DDS_1)/2
ref
out
out
1
1
1
ƒ
= ƒ × N × (DDS_1 + 4 × dev)/2
ref
Table 5. Operating Mode Per STDBY Terminal
STDBY
OPERATING MODE
Standby/programming mode – power down of all blocks
Operating mode and programming mode
0
1
Two independent operating modes, Mode0 and Mode1, allow extremely fast switching between two
preprogrammed settings by toggling the MODE terminal. Each mode can be viewed as a bank of configuration
registers which store the frequency settings and the enable/disable settings for each functional block of the
TRF6900. The MODE terminal is then used to asynchronously switch between Mode0 and Mode1 as shown
in Figure 25. Several examples of operating sequences are shown in Table 6.
26
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TI [ TEXAS INSTRUMENTS ]
