2. Power Supply Sequencing
The Si5357 VDD_core voltages are VDD_DIG, VDD_XTAL and VDDA. These 3 VDD_core pins must all use the *same* voltage.
Power supply sequencing between VDD_core and any VDDOx pin is allowed in any order. However, to minimize the “bring up” time,
it is recommended that VDD_core is powered up first, this ensures that the NVM download is completed first. The register bit field
“VDD_XTAL_OK” is set to indicate input buffer(s) and crystal oscillator are powered up. Once the appropriate VDDOx supplies are
powered-up, the VDDO_OK register field will indicate output driver bank supply voltage status. These status registers are available
to provide an indication of general device status and presence of output driver voltages. The figure below shows the Si5332 device
power-up sequencing and expected device behavior. Note that a blank (unconfigured) part will stop and wait to be configured with
outputs disabled.
Power supplies for VDDA,
VDD_DIG, VDD_XTAL
stable
Time (system time delay)
for NVM download
Is this a blank part?
Yes
No
Time (system time delay) for
Oscillator startup/ Time
(system time delay) for input
clock availability
Time (system time delay)
for PLL lock
Outputs available and
stable
Program Si5332 volatile
memory with a frequency
plan
Figure 2.1. Power Supply Sequencing for Si5357
Si5357 Reference Manual • Power Supply Sequencing
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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Rev. 0.2 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • July 26, 2021
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