Datasheet

V850ES/JG3-H, V850ES/JH3-H CHAPTER 21 USB FUNCTION CONTROLLER (USBF)
R01UH0042EJ0500 Rev.5.00 Page 1048 of 1513
Aug 12, 2011
(3) Detection of USB cable connection/disconnection
The USB function controller (USBF) requires a VBUS input signal to recognize whether the USB cable is connected
or disconnected, because the state of the USBF is controlled by hardware. The voltage from the USB host or HUB
(5 V) is applied as the VBUS input signal when the USB cable VBUS is connected to the USB host or HUB while
the USBF power is off. Therefore, for IC1 in Figure 21-3, use an IC to which voltage can be applied when the
system power is off. When disconnecting the USB cable in the circuit in Figure 21-3, the input signal to INTP10
may be unstable while the VBUS voltage is dropping. It is therefore recommended to use a Schmitt buffer for IC1 in
Figure 21-3.
(4) Floating protection during initialization or when USBF is unused
When the USB function controller is initialized or unused, to avoid a floating status, pull the D+/D− pins down using
a resistor of 50 kΩ or higher.