Example Of Connection - NEC uPD98502 User Manual

6.10 Example of Connection

USB Controller is connected to the µ PD98502 internal USB I/O buffer as shown in the following Figure 6-32.
When designing a PCB, it is necessary to connect a 1.5 kΩ pull-up resistor between the D+ pin and the 3.3 V
power supply to indicate the presence of a full-speed device.
To avoid current floating on the integrated USB Buffer it is recommended to place a 51 kΩ pull-down resistor
between the D- pin and the GND.
The circuit must be designed such that the µ PD98502 power supply is turned on and off together with the external
3.3 V power supply. If the µ PD98502 power supply is off, but the external 3.3 V power supply is on, the USB HUB
connected to the µ PD98502 will assume that a new device has been connected but, because the µ PD98502 power is
off, no response can be returned.
For details of the electrical specifications of the USB, refer to USB Specification 1.1.
CHAPTER 6 USB CONTROLLER
Figure 6-32. Example of Connection
D +
+3.3 V
B uffer
Ω
1.5 k
D +
C onnect to
H U B
D -
D -
Ω
51 k
B uffer
G N D
µ
P D 98502
Preliminary User's Manual S15543EJ1V0UM
U S B C ontroller
Y 1
IS E
C N A
C N B
O S E
A
O E N
369