Analog Devices ADF7021-V Manual page 40

ADF7021-V
The recommended programming sequences for transmit and
receive are shown in Figure 54 and Figure 55, respectively.
WAIT 50µs (REGULATOR POWER-UP)
CHECK FOR REGULATOR READY
OPTIONAL. ONLY NECESSARY IF PA
RAMP-DOWN IS REQUIRED.
TCXO
REFERENCE
TURN ON EXTERNAL VCO AND
ALLOW ADEQUATE SETTLING
CE HIGH
WRITE TO REGISTER 3 (TURNS ON Tx/Rx CLOCKS)
WRITE TO REGISTER 0 (TURNS ON PLL)
WAIT 40µs (TYPICAL PLL SETTLING)
WRITE TO REGISTER 2 (TURNS ON PA)
WAIT FOR PA TO RAMP UP (ONLY IF PA RAMP ENABLED)
WAIT FOR Tx LATENCY NUMBER OF BITS
WRITE TO REGISTER 2 (TURNS OFF PA)
WAIT FOR PA TO RAMP DOWN
Figure 54. Power-Up Sequence for Transmit Mode
The difference in the power-up routine for a TCXO and XTAL
reference is shown in these figures.
POWER-DOWN
CE LOW
REFERENCE
(REGULATOR POWER-UP + TYPICAL XTAL SETTLING)
WRITE TO REGISTER 1
Tx MODE
(REFER TO TABLE 11)
CE LOW
POWER-DOWN
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XTAL
CE HIGH
WAIT 50µs + 1ms
CHECK FOR REGULATOR READY