CS2300-CP

DS843F1

19

5.4

PLL Clock Output

The PLL clock output pin (CLK_OUT) provides a buffered version of the output of the frequency synthesizer.

The driver can be set to high-impedance with the ClkOutDis bit.

The output from the PLL automatically drives a static low condition while the PLL is un-locked (when the

clock may be unreliable). This feature can be disabled by setting the ClkOutUnl bit, however the state

CLK_OUT may then be unreliable during an unlock condition.

Figure 16. PLL Clock Output Options

5.5

Auxiliary Output

The auxiliary output pin (AUX_OUT) can be mapped, as shown in Figure 17, to one of three signals: input

clock (CLK_IN), additional PLL clock output (CLK_OUT), or a PLL lock indicator (Lock). The mux is con-

trolled via the AuxOutSrc[1:0] bits. If AUX_OUT is set to Lock, the AuxLockCfg bit is then used to control

the output driver type and polarity of the LOCK signal (see section 8.6.2 on page 27). If AUX_OUT is set to

CLK_OUT the phase of the PLL Clock Output signal on AUX_OUT may differ from the CLK_OUT pin. The

driver for the pin can be set to high-impedance using the AuxOutDis bit.

Figure 17. Auxiliary Output Selection

Referenced Control

Register Location

ClkOutUnl.............................. “Enable PLL Clock Output on Unlock (ClkOutUnl)” on page 28

ClkOutDis .............................. “PLL Clock Output Disable (ClkOutDis)” on page 25

Referenced Control

Register Location

AuxOutSrc[1:0]...................... “Auxiliary Output Source Selection (AuxOutSrc[1:0])” on page 25

AuxOutDis .............................“Auxiliary Output Disable (AuxOutDis)” on page 24

AuxLockCfg........................... “AUX PLL Lock Output Configuration (AuxLockCfg)” section on page 27

PLL Locked/Unlocked

PLL Output

2:1 Mux

ClkOutDis

2:1 Mux

ClkOutUnl

0

PLL Clock Output Pin

(CLK_OUT)

0

1

0

1

PLL Clock Output

PLLClkOut

3:1 Mux

Auxiliary Output Pin

(AUX_OUT)

AuxOutDis

AuxOutSrc[1:0]

AuxLockCfg

Frequency Reference Clock

(CLK_IN)

PLL Clock Output

(PLLClkOut)

PLL Lock/Unlock Indication

(Lock)