Vbus Power Supply Circuit - Renesas RZ/A Series Manuallines

RZ/A1

5. VBUS Power Supply Circuit

Notes on designing the VBUS power supply circuit are described below.
• When RZ/A1 is used as a host controller, the additional capacity of the VBUS line should be designed to
be 120 µF or more.
• When RZ/A1 is used as a function controller, the additional capacity of the VBUS line should be designed
to be between 1.0 µF and 10 µF.
• The VBUS line should include a filter circuit as overshoot may be caused by inconsistent impedance
when the USB cable is connected. As a filter circuit, add a 1.0 µF to 10 µF capacitor and 100 Ω to 1 kΩ
resistor. The final constants should be defined after confirming that an overshoot has not occurred on the
board. Also, a resistor of more than 1 kΩ should not be added.
• When used as a host controller, the VBUS power supply must be supplied to the function devices. A
power supply switch IC with over-current protection for the USB power supply bus (hereinafter called
"USB power supply switch IC"), such as the Renesas Electronics ISL6186 is recommended for the VBUS
power supply control. Make sure to consider the limitation value of the current for the VBUS power supply
line based on the current value used by the applicable system power supply and the USB function
devices being communicated with. In addition, when designing the VBUS power supply control circuit,
refer to the example circuits described in the USB power supply switch IC datasheet.
Figure 5.1 shows an example of the VBUS power supply circuit when it is used as a host controller and
Figure 5.2 shows an example of the VBUS power supply circuit when it is used as a function controller.
RZ/A1
General input/output
port (output)
Interrupt pin
VBUSn
Notes: n = 0 or 1
*1. IRQ pin or TINT pin.
Figure 5.1
R01AN5119EJ0120 Rev.1.20
May.26.20
USB power supply
3.3 V 5 V
switch IC (ISL6186)
VIN
EN
*1 FLT#
1.0 µF to 10 µF
Example of VBUS circuit for using RZ/A1 as a host controller
Guidelines for High-Speed USB2.0 Board Design
OUT
120 µF or
higher
GND
100 Ω to 1 kΩ
Digital ground
(DGND)
Filter circuit
USB connector
VBUS
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