AN2865

Application circuit

Doc ID 15283 Rev 1

5/17

The external resistors are very important to guarantee proper operation:

– The R1 and R2 series resistors are needed to mask the DP/DM pins’ parasitic

capacitance which is seen on the bus during high-speed USB communication.

Removing these resistors might lead to degradation of USB high-speed signal quality

and eye pattern failure. A value of 470

Ω is suggested in order to have optimal

performance;

are applied (node B). Every device needing overvoltage protection must be

application circuit (node A). Bus-powered devices cannot take advantage of this

cause a voltage drop over the R3 resistor. If this voltage drop is too high, the device's

It is therefore strongly recommended to connect bus-powered USB devices directly to

Table 1.

STUSBCD01B operating modes

Shutdown

Status/method

pin

Default method

pin

Operating mode

< 2.2 V

-

-

-

-

-

Power down

> 2.2 V

Not

present

Not

present

-

-

-

Standby (no SW control)

> 2.2 V

Not

present

Present

-

-

Active, HW detection,

current sink method

> 2.2 V

Not

present

Present

-

-

GND

Active, HW detection,

dedicated method

> 2.2 V

Present

Present

-

-

Standby (SW control)

> 2.2 V

Present

Not

present

-

-

-

Standby (SW control)

> 2.2 V

Present

Present

GND

(1)

-

Active, SW detection,

current sink method

> 2.2 V

Present

Present

GND

-

Active, SW detection,

dedicated method

1.

The level of the Status/Method pin is read and latched on the falling edge of the shutdown input signal. When detection is

finished, this pin becomes output.

SW = Software: HW = Hardware; “-” = Don't Care