CS2000-OTP_09 Datasheet, PDF(19/30 Page) Cirrus Logic – Fractional-N Clock Synthesizer & Clock Multiplier

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CS2000-OTP_09 Datasheet, PDF (19/30 Pages) Cirrus Logic – Fractional-N Clock Synthesizer & Clock Multiplier

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5.7 Mode Pin Functionality

CS2000-OTP

5.7.1

M1 and M0 Mode Pin Functionality

M[1:0] determine the functional mode of the device and select both the default User Defined Ratio and

the set of modal parameters. The modal parameters are RModSel[1:0], AuxOutSrc[1:0], LockClk[1:0], and

FracNSrc. By modifying one or more of the modal parameters between the 4 sets, different functional con-

figurations can be achieved. However, global parameters are fixed and the same value will be applied to

each functional configuration. Figure 17 on page 22 provides a summary of all parameters used by the

device.

5.7.2

M2 Mode Pin Functionality

M2 usage is mapped to one of the optional special functions via the M2Config[2:0] global parameter. De-

pending on what M2 is mapped to, it will either act as an output enable/disable pin or override certain mod-

al parameters. Figure 16 summarizes the available options and the following sections will describe each

option in more detail.

M2Config[2:0] global parameter

5.7.2.1

5.7.2.2

M2 pin

000

Disable CLK_OUT pin

001

Disable AUX_OUT pin

010

Disable CLK_OUT and AUX_OUT pins

011

RModSel[1:0] Modal Parameter Enable

100

Force Manual Fractional N Source Selection

101

Reserved

110

FracNSrc Modal Parameter Override

111

Force AuxOutSel[1:0] = 10 (PLL Clock Out)

Figure 16. M2 Mapping Options

M2 Configured as Output Disable

If M2Config[2:0] is set to either â000â, â001â, or â010â, M2 becomes an output disable pin for one or

both output pins. If M2 is driven âlowâ, the corresponding output(s) will be enabled, if M2 is driven

âhighâ, the corresponding output(s) will be disabled.

M2 Configured as R-Mod Enable

If M2Config[2:0] is set to â011â, M2 becomes the R-Mod enable pin. It should be noted that M2 is

the only way to enable R-Mod. Even though the RModSel[1:0] modal parameter can be set arbi-

trarily for each configuration set, it will not take effect unless enabled via M2. If M2 is driven âlowâ,

R-Mod will be disabled, if M2 is driven âhighâ R-Mod will be enabled.

DS758F1

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