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6.1.10 Power LED

The power LED is a blue LED that will turn on once the

TPS65217C

has finished the

power up procedure. If you ever see the LED flash once, that means that the

TPS65217C

started the process and encountered an issue that caused it to shut down. The

connection of the LED is shown in

Figure 25

6.1.11 TPS65217C Power Up Process

Figure 28

shows the interface between the

TPS65217C

and the processor. It is a cut from

the PDF form of the schematic and reflects what is on the schematic.

Figure 28 Power Processor Interfaces

When voltage is applied, DC or USB, the

TPS65217C

connects the power to the SYS

output pin which drives the switchers and LDOs in the

TPS65217C

At power up all switchers and LDOs are off except for the

VRTC LDO

(1.8V), which

provides power to the VRTC rail and controls the

RTC_PORZn

input pin to the processor,

which starts the power up process of the processor. Once the RTC rail powers up, the

RTC_PORZn

pin, driven by the

LDO_PGOOD

signal from the

TPS65217C

, of the

processor is released.

Once the

RTC_PORZn

reset is released, the processor starts the initialization process.

After the RTC stabilizes, the processor launches the rest of the power up process by

activating the

PMIC_POWER_EN

signal that is connected to the

TPS65217C

which starts

the

TPS65217C

power up process.

The

LDO_PGOOD

signal is provided by the

TPS65217C

to the processor. As this

signal is 1.8V from the

TPS65217C

by virtue of the

TPS65217C

VIO rail being set to

1.8V, and the

RTC_PORZ

signal on the processor is 3.3V, a voltage level shifter,

, is

used. Once the LDOs and switchers are up on the

TPS65217C

, this signal goes active

releasing the processor. The LDOs on the

TPS65217C

are used to power the VRTC rail

on the processor.