5.3.9 Output Driver State When Disabled
The disabled state of an output driver is configurable as: disable low, disable high, or disable mid. When set for disable mid, the output
common mode voltage will stay nearly the same when disabled as when enabled. The output common mode voltage is maintained
while the driver is disabled, reducing enable/disable transients. By contrast, powering down the driver rather than disabling it increases
output impedance and shuts off the output common mode voltage. For all output drivers connected in the system, it is recommended
to use Disable rather than Powerdown to reduce enable/disable common mode transients. Unused outputs may be left unconnected,
powered down to reduce current draw, and, with the corresponding VDDOx, left unconnected.
Table 5.8. Output Driver Disable State Control Registers
Setting Name
Hex Address [Bit Field]
Function
Si5341
Si5340
OUT0_DIS_STATE
OUT1_DIS_STATE
OUT2_DIS_STATE
OUT3_DIS_STATE
OUT4_DIS_STATE
OUT5_DIS_STATE
OUT6_DIS_STATE
OUT7_DIS_STATE
OUT8_DIS_STATE
OUT9_DIS_STATE
0109[5:4]
010E[5:4]
0113[5:4]
0118[5:4]
011D[5:4]
0122[5:4]
0127[5:4]
012C[5:4]
0131[5:4]
013B[5:4]
0113[5:4]
0118[5:4]
0127[5:4]
012C[5:4]
—
—
—
—
—
—
Determines the state of an output driver when disabled. Selecta-
ble as:
• Disable logic low.
• Disable logic high
5.3.10 Synchronous/Asynchronous Output Disable Feature
Outputs can be configured to disable synchronously or asynchronously. In synchronous disable mode the output will wait until a clock
period has completed before the driver is disabled. This prevents unwanted runt pulses from occurring when disabling an output. In
asynchronous disable mode the output clock will disable immediately without waiting for the period to complete.
Table 5.9. Synchronous Disable Control Registers
Setting Name
Hex Address [Bit Field]
Function
Si5341
Si5340
OUT0_SYNC_EN
OUT1_SYNC_EN
OUT2_SYNC_EN
OUT3_SYNC_EN
OUT4_SYNC_EN
OUT5_SYNC_EN
OUT6_SYNC_EN
OUT7_SYNC_EN
OUT8_SYNC_EN
OUT9_SYNC_EN
0109[3]
010E[3]
0113[3]
0118[3]
011D[3]
0122[3]
0127[3]
012C[3]
0131[3]
013B[3]
0113[3]
0118[3]
0127[3]
012C[3]
—
—
—
—
—
—
When this bit is high, the output will turn on/off (enable/disable)
without generating runt pulses or glitches. The default for this bit
is high. When this bit is low, the outputs will turn on/off asynchro-
nously. In this case, there may be glitches on the output when it
turns on/off.
Si5341, Si5340 Rev D Family Reference Manual • Output Clocks
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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Rev. 1.3 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • July 26, 2021
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