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2015-08-0013

PT0572

09/24/15

24

PI5USB2546Q

USB Charging Port Controller and Load Detection Power Switch

Port Power Management (PPM)

PPM is the intelligent and dynamic allocation of power. It is for systems that have multiple charging ports but cannot power them

all simultaneously.

Goal of this feature are:

1.

Enhances user experience since user does not have to search for charging port

2.

Power supply only has to be designed for a reasonable charging load

Initially all ports are allowed to broadcast high current charging, charging current limit is based on ILIM_HI resistor setting.

System monitors /STATUS to see when high current loads are present. Once allowed number of ports assert /STATUS, remaining

ports are toggled to a non-charging port. Non-charging ports are SDP ports with current limit based on ILIM_LO. PI5USB2546Q

allows for a system to toggle between charging and non-charging ports either with an OUT discharge or without an OUT

discharge.

Benefits of PPM

•

Delivers better user experience

•

Prevents overloading of system's power supply

•

Allows for dynamic power limits based on system state

•

Allows every port to potentially be a high power charging port

•

Allows for smaller power supply capacity since the loading is controlled

PPM Details

All ports are allowed to broadcast high current charging – CDP or DCP. Current limit is based on ILIM_HI and system monitors

/STATUS pin to see when high current loads are present. Once allowed number of ports assert /STATUS, remaining ports are

toggled to a SDP non-charging port. SDP current limit is based on ILIM_LO setting. SDP ports are automatically toggled back to

CDP or DCP mode when a charging port de-asserts /STATUS.

Based on CTL settings there is a provision for a port to toggle between charging and non-charging ports either with a VBUS

discharge or without a VBUS discharge. For example when a port is in SDP2 mode (1110) and its ILIM_SEL pin is toggled to 1

due to another port releasing its high current requirements. The SDP2 port will automatically revert to CDP mode (1111) without a

discharge event. This is desirable if this port was connected to a media device where it was syncing data from the SDP2 port; a

discharge event would mess-up the syncing activity on the port and cause user confusion.

/STATUS trip point is based on the programmable ILIM_LO current limit set point. This does not mean /STATUS is a current

limit – the port itself is using the ILIM_HI current limit. Since ILIM_LO defines the current limit for a SDP port, it works well to

use the ILIM_LO value to define a high current load. /STATUS asserts in CDP and DCP when load current is above

ILIM_LO+25mA for 200ms. /STATUS de-asserts in CDP and DCP when load current is below ILIM_LO-25mA for 3s.