Analog Devices ADRV9005 Reference Manual page 91

Reference Manual
MICROPROCESSOR AND SYSTEM CONTROL
– t if t is greater than t
TxEnaRise2On RxEnaFall2Off
t − t before TX_ENABLE falling edge.
TxEnaRise2On RxEnaFall2Off
Figure 72. Minimum Guard Time Between RX_ENABLE Falling Edge and TX_ENABLE Rising Edge
Guard Time Between TX_ENABLE Falling Edge and TX_ENABLE Rising Edge
The guard time between TX_ENABLE falling edge and TX_ENABLE rising edge makes sure the interface is turned off at the end of the
previous frame before it turns on again for the next frame. In addition, it must also make sure the AFE is powered off in the previous frame
before powering up again in the new frame. Because it takes t
next TX_ENABLE rising edge must come after a delay of at least t
frame before it turns on again for the next frame. As it takes t
the next TX_ENABLE rising edge must come after a delay of at least equal to t
off in the previous frame before powering up again in the new frame. If the timing parameters are set appropriately, these two conditions are
almost identical. If they are not identical for some reason, set the guard time as the maximum of t
Figure 73 describes this scenario.
Figure 73. Minimum Guard Time Between TX_ENABLE Falling Edge and TX_ENABLE Rising Edge
Guard Time Between RX_ENABLE Falling Edge and RX_ENABLE Rising Edge
The guard time between the RX_ENABLE falling edge and RX_ENABLE rising edge makes sure the interface is turned off at the end of the
previous frame before it turns on again for the next frame. Because it takes t
falling edge, the next RX_ENABLE rising edge must come after a delay of at least t
of the previous frame before it turns on again for the next frame. Because the analog powers down before the interface, the AFE is guaranteed
to power down before being powered up at the start of the next frame if this condition is met.
Figure 74. Minimum Guard Time Between RX_ENABLE Falling Edge and RX_ENABLE Rising Edge
Hold Time Between TX_ENABLE Rising Edge and TX_ENABLE Falling Edge
After a TX_ENABLE rising edge, its falling edge must come after a delay of at least t
switch). To actually transmit, the channel must be on for a duration longer than its propagation delay. Achieve this either by making sure
that TX_ENABLE is high for longer than the propagation delay, or by ensuring the t
describes this scenario.
Figure 75. Minimum Hold Time Between TX_ENABLE Rising Edge and TX_ENABLE Falling Edge
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. For t is less than t
TxEnaRise2On RxEnaFall2Off
Figure 72 describes both cases.
to turn off the transmit interface after the TX_ENABLE falling edge, the
TxEnaHold
TxEnaHold
to power down the transmitter AFE after the TX_ENABLE falling edge,
TxEnaFall2Off
, TX_ENABLE rising edge can happen
TxEnaRise2On
. This ensures the interface is turned off at the end of the previous
− t
TxEnaFall2Off TxEnaRise2AnaOn
TxEnaHold
to turn off the receive interface after the RX_ENABLE
RxEnaHold
. This ensures the interface is turned off at the end
RxEnaHold
Figure 74 describes this scenario.
or t
TxEnaRise2AnaOn TxEnaRise2On
and t
TxEnaHold TxEnaFall2Off
ADRV9001
. This ensures the AFE is powered
and t − t
TxEnaFall2Off TxEnaRise2AnaOn
(if controlling the antenna
are longer than t . Figure 75
TxPD
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.