USB3803 datasheet(15/99 Pages) MICROCHIP

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DS00001691B-page 15

USB3803

4.0

MODES OF OPERATION

The USB3803 has modes of operation - Standby Mode, Bypass Mode (USB3803C only) and Hub Mode which balance

power consumption with functionality. The operating mode of the USB3803 is selected by setting values on primary

inputs according to the table below.

Note 1:

Bypass mode is only available in the USB3803C. The BYPASS_N pin must always be driven high in the

USB3803B. Refer to Section 1.0, "General Description," on page 4 for a list of differences between each

version of the USB3803.

4.1

Operational Mode Flowchart

The flowchart in Figure 4-1 shows the modes of operation. It also shows how the USB3803 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 23

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 21.

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

BYPASS_N

Input (Note 1)

Resulting

Mode

Summary

Standby

Lowest Power Mode – no function other than monitoring

RESET_N and BYPASS_N inputs to move to higher

states. Switch Resistance is RSTDBY. All regulators are

powered off.

Bypass

(Note 1)

Low Power Mode - Bypass Switch connects bypass port

(downstream port 3) to upstream port with low switch

resistance RON.

Hub

Full Feature Mode - Operates as a configurable USB hub

with battery charger detection. Switch is disabled and

assumes high switch resistance ROFF. Power consump-

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

they are running and amount of data transferred (refer to

Table 10-3 and Table 10-4).

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