SNAS669E September 2015 – April 2018 LMK03318
PRODUCTION DATA.
If the VDD_IN, VDD_PLL, VDD_LDO, VDD_DIG, and VDDO supplies are driven from different supply rails, 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. The PDN input incorporates a 200-kΩ resistor to VDDO_01 and as shown in Figure 84, a capacitor from the PDN pin to GND can be used to form a R-C time constant with the internal pullup resistor or an external pullup resistor. This R-C time constant can be designed to delay the low-to-high transition of PDN until all core and output supplies have reached their minimum voltage tolerances. Alternatively, the delayed PDN low-to-high transition could be controlled by a logic output of a host controller (CPLD/FPGA/CPU) or power sequencer.