CHAPTER 6 USB CONTROLLER
Preliminary User’s Manual S15543EJ1V0UM
369
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
.
Figure 6-32. Example of Connection
O S E
C onnect to
H U B
+3.3 V
A
µ
P D 9 8502
D +
D -
U S B C ontrolle r
D +
B uffe r
O E N
IS E
Y 1
D -
B uffe r
C N B
C N A
1.5 k
Ω
G N D
51 k
Ω
When designing a PCB, it is necessary to connect a 1.5 k
Ω
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 k
Ω
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.