HD6417660 RENESAS [Renesas Technology Corp], HD6417660 Datasheet - Page 544

• Manufacturer Part Number: HD6417660
• Description: Renesas 32-Bit RISC Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

• D+ Pull-up Control
Rev. 1.00, 02/04, page 506 of 804
Control D+ pull-up via the USB_PULLUP pin in the system in case that the connection-
notification (D+ pull-up) of connection to the USB host controller or hub is to be inhibited
(i.e., during high-priority processing or initialization processing).
The D+ pull-up control signal and USB_VBUS pin input signal should be controlled via the
USB_PULLUP pin and the USB cable VBUS (AND circuit) as shown in the examples in
figure 18.2.
D+ pull-up is inhibited when the USB_PULLUP pin is low in an example of figure 18.2. (The
initial setting of the USB_PWR_EN/USB_PULLUP pin is low.)
Pull-up D+ after confirming that USB_VBUS pin became high, when the pull-up control is
performed directly by USB_PULLUP pin as is shown in an example of figure 18.3.
Use an IC such that allows voltage application when system power is off (for example,
HD74LV1G126A) for the pull-up control IC (IC2 in figures 18.2 and 18.3).
(The UDC core in this LSI holds the powered state when USB_VBUS pin is low, regardless of
the D+/D− state.)
Figure 18.3 Example 2 of Connection between USB Function Controller and
USB function controller
This LSI
USB_PULLUP
USB_VBUS
USB_N
USB_P
External Circuit
IC allowing voltage
application when
system power is off
3.3V
IC1
27Ω
27Ω
IC2
IC allowing voltage
application when
system power is off
1.5kΩ
USB connector
5V
VBUS
D+
D-
GND