USB Pin Multiplexing
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14.5 USB Pin Multiplexing
OMAP5910 USB signal multiplexing provides five main types of signaling:
USB host and USB function with USB transceivers, USB host and USB func-
tion without USB transceivers, and UART1. This section describes first gener-
al external connectivity for these types of multiplexing and then the
specific OMAP5910 USB multiplexing modes along with specific OMAP5910
connectivity for each mode.
14.5.1 Host Controller Connectivity With USB Transceivers
To provide a robust USB solution, a system that provides a USB host controller
must implement certain features. These features include a USB-type A
receptacle, power on the VBUS signal (may be switched or unswitched
power), transient suppression, pulldown resistors, and USB-compatible
downstream port transceiver. These elements are shown in Figure 14–3.
Figure 14–3. Typical USB Host Connections
USB
transceiver
VBUS
control
USB type
A
receptacle
Transient
suppressor
USB host
controller
R1
R2
R3
R4
R1, R2
R3, R4
C1
U1
U2
Value depends on transceiver
15K Ohm +/– 5%
Low ESR cap, minimum 120 uF
Transient suppressor, such as SN65220, SN65240, or SN75240
Power switch, such as TPS2014 or TPS2015
U1
U2
+5 V
+3.3 V
C1
(OMAP5910 does not provide a
dedicated pin for these connections)
VBUS_EN
Overcurrent
VBUS
D+
D–