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DS00002103A-page 23

USB3500

The OTG Module can be broken into 4 main blocks; ID Detection, VBUS Control, Driving External VBUS, and External

VBUS Detection. Each of these blocks is covered in the sections below.

5.7.1

ID DETECTION

The USB3500 provides an ID pin to determine the type of USB cable connected. When the Mini-A Plug of a USB cable

is inserted into the Mini-AB connector, the ID pin is shorted to ground. When the Mini-B Plug is inserted into the Mini-

AB connector, the ID pin is allowed to float.

The USB3500 provides an integrated pull-up resistor to pull the ID pin to VDD3.3 when a Mini-B plug is inserted and

the cable is floating. When a Mini-A plug is connected, the pull-up resistor will be overpowered and the ID pin will be

brought to ground. To save current when a Mini-A Plug is inserted, the ID pull-up resistor can be disabled by clearing

the IDPULLUP pin. To prevent the ID pin from floating to a random value, a weak pull-up resistor is provided at all times.

The circuits related to the ID comparator are shown in Figure 5-8 and their related parameters are shown in Table 4-7.

FIGURE 5-8:

USB3500 ON-THE-GO MODULE

TABLE 5-2:

IDGND VS. USB CABLE TYPE

USB Plug

OTG Role

ID Voltage

IDGND

AHOST

0

0

B

PERIPHERAL

3.3

1

OTG Module

VBUS

ID

VDD33

VBUSVLD

SESSVLD

SESSEND

IDPULLUP

DISCHRGVBUS

ID_DIG

CHRGVBUS

0.5V

1.4V

4.575V

0.6V