SNAS669E September 2015 – April 2018 LMK03318
PRODUCTION DATA.
In case the VDD_IN, VDD_PLL, VDD_LDO, and VDD_DIG, and VDDO supplies ramp slowly with a ramp time over 100 ms, TI recommends starting the device POR sequence after all core and output supplies have reached their minimum voltage tolerances (VDD ≥ 3.135 V and VDDO ≥ 1.71 V). This can be realized by delaying the PDN low-to-high transition in a manner similar to the condition detailed in Powering Up From Split-Supply Rails and shown in Figure 84.
If a VDD supply cannot reach 3.135 V before the PDN low-to-high transition, TI recommends toggling the PDN pin again or chip soft reset bit in R12.7 after all VDD and VDDO supplies reached their minimum tolerances to re-trigger the device POR sequence for normal chip operation.
If only VDDO supplies ramp after the PDN low-to-high transition, issuing a channel reset on any PLL-driven output channel with its PLL SYNC enabled (PLL_SYNC_EN=1) is recommended to ensure normal output divider operation without requiring a full chip reset (through PDN pin or soft reset). A local channel reset can be issued by toggling the corresponding power-down bit(s) in R30 after its VDDO supply has reached 1.71 V. Alternatively, an output SYNC can be issued to reset any SYNC-enabled channel (see Output Synchronization).