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1/18/2017

2016-11-0004

PT0493-4

20

PI5USB2546

Load Detect

PI5USB2546 offer system designers unique power management strategy not available in the industry from similar devices.

There are two power management schemes supported by the PI5USB2546 via the /STATUS pin, they are:

1.

Power Wake (PW)

2.

Port Power Management (PPM)

Either feature may be implemented in a system depending on power savings goals for the system. In general Power Wake

feature is used mainly in mobile systems like a notebook where it is imperative to save battery power when system is in deep

sleep (S4/S5) state. On the other hand Port Power Management feature would be implemented where multiple charging ports

are supported in the same system and system power rating is not capable of supporting high current charging on multiple ports

simultaneously.

Power Wake

Goal of power wake feature is to save system power when system is in S4/S5 state. In S4/S5 state system is in deep sleep and

typically running of the battery; so every “mW” in system power savings will translate to extending battery life. In this state the

PI5USB2546 will monitor charging current at the OUT pin and provide a mechanism via the /STATUS pin to switch out the

high power DC-DC controller and switch in a low power LDO when charging current requirement is <45mA (typ.). This would

be the case when no peripheral device is connected at the charging port or if a device has attained its full battery charge and

draws <45mA. Power wake flow chart and description is shown as Figure 6.