SH7721 datasheet(823/1524 Pages) RENESAS

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Section 23

USB Pin Multiplex Controller

Rev. 3.00 Jan. 18, 2008 Page 761 of 1458

REJ09B0033-0300

• Detection of USB Cable Connection/Disconnection

As USB function controller in this LSI manages the state by hardware, USB_VBUS signal is

necessary to recognize connection or disconnection of the USB cable. The power supply signal

(VBUS) in the USB cable is used for USBF_VBUS. However, if the cable is connected to the

USB host or hub when the power of USB function controller (this LSI—installed system) is

off, a voltage of 5 V will be applied from the USB host or hub.

Therefore, use an IC such that allows voltage application when system power is off (for

example, HD74LV1G08A) for the IC1 in figures 23.2 to 23.5.

To recover from the standby state with the USB cable connected, the IRQ pin should be

connected to the USB cable. (Recovery from the software standby state cannot be performed

by a USB connection/disconnection interrupt.)

23.4.2

Example of the Connection between USB Host Controller and Transceiver

Figures 23.4 and 23.5 show example connections of the USB host controller and transceiver.

Figure 23.4 shows an example connection using the built-in transceiver 1. By using the

USB2_ovr_current, USB2_pwr_en, USB2_P, and USB2_M pins in an external circuit similar to

that in figure 23.4, you can also use built-in USB transceiver 2. Figure 23.5 shows an example

connection when not using the built-in USB transceiver. When using the USB host controller, a

separate LSI must be used for USB power bus control (equivalent to the USB power control LSIs

in figures 23.4 and 23.5). Make sure the LSI has the power supply capacity to satisfy the USB

standard, and select one that has an overcurrent protection function. Configure the system so that

the input to the

USB1_ovr_current pin is Low on detection of an overcurrent.

SH7721 Datasheet(PDF) 823 Page - Renesas Technology Corp