USB3503 datasheet(15/73 Pages) MICROCHIP

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DS00001584B-page 15

USB3503

4.0

MODES OF OPERATION

The USB3503 provides two modes of operation - Standby Mode and Hub Mode - which balance power consumption

with functionality. The operating mode of the USB3503 is selected by setting values on primary inputs according to the

table below.

4.1

Operational Mode Flowchart

The flowchart in Figure 4-1 shows the modes of operation. It also shows how the USB3503 traverses through the Hub

mode stages (shown in bold.) The flow of control is dictated by control register bits shown in Italics as well as other

events such as availability of reference clock. Refer to Section 5.3, "Serial Interface Register Definitions," on page 21

for the detailed definition of the control register bits. In this specification register bits are referenced using the syntax

<Register>.<RegisterBit>. A summary of all registers can be found in Table 5-2, “Serial Interface Registers,” on

page 19.

The remaining sections in this chapter provide more detail on each stage and mode of operation.

TABLE 4-1:

CONTROLLING MODES OF OPERATION

RESET_N

Input

Resulting Mode

Summary

Standby

Lowest Power Mode – no function other than monitoring RESET_N

input to move to higher states. All regulators are powered off.

Hub

Full Feature Mode - Operates as a configurable USB hub. Power

consumption based on how many ports are active, at what speeds

they are running and amount of data transferred.

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