Transmitter Description
User Manual
63
STEL-2176
NCO LOADING (USER CONTROLLED)
OUTPUT
TXFCWSEL
1-0
TXNCOLD
OLD FREQ.
DON'T CARE
tFCWSU
VALID
DON'T CARE
tFCWHD
NEW FREQ.
tLDPIPE
NOTE 1
WCP 53816.c-12/5/97
NCO LOADING (AUTOMATIC)
OUTPUT
TXFCWSEL
1-0
TXDATAENO
ZERO
DON'T CARE
tDENHV
tDENLZ
SELECTED FREQUENCY
ZERO
VALID
DON'T CARE
tDOFCWV
tDOFCWI
WCP 53817.c-12/5/97
NOTE 1: The first rising edge of CLK after TXNCOLD goes high initiates the load process.
Table 57. NCO Loading AC Characteristics
(V
DD
= 3.3 V
±
10%, V
SS
= 0 V, T
a
= Ð40
°
to 85
°
C)
Symbol
Parameter
Min.
Nom.
Max.
Units
Conditions
t
LDPIPE
NCO-LD to Change in Output Frequency Pipeline
Delay
23
CLK cycles
t
FCWSU
TXFCWSEL
1-0
to NCO-LD Setup
3
CLK cycles
t
FCWHD
TXFCWSEL
1-0
to NCO-LD Hold
10
CLK cycles
t
DENLZ
TXDATAENO Low to Zero Frequency Out Delay
23
CLK cycles
t
DENHV
TXDATAENO High to Valid Frequency Out
Delay
23
CLK cycles
t
DOFCWV
TXDATAENO to TXFCWSEL
1-0
Valid
3
CLK cycles
t
DOFCWI
TXDATAENO to TXFCWSEL
1-0
Invalid
10
CLK cycles