Datasheet

Functional Description
MC13783 Technical Data, Rev. 3.5
44 Freescale Semiconductor
4.5.1.1.4 Full Speed/ Low Speed Configuration
The USB transceiver supports the low speed mode of 1.5 Mbits/second and the full speed mode of 12
Mbits/second. To indicate the speed to the host an internal 1.5 kOhm pull up to VUSB is used. Via SPI this
resistor can be connected to UDP to indicate full speed, or to UDM to indicate low speed.
4.5.1.1.5 USB Suspend
USB suspend mode is enabled through SPI. When set, the USB transceiver enters a low power mode which
reduces the transceiver current drain to below 500 µA. In USB suspend mode, the VUSB regulator remains
enabled and the VBUS detect comparators remain enabled, while the single ended receivers are switched
from a comparator to a Schmitt-trigger buffer.
4.5.1.1.6 USB On-The-Go
USBOTG support circuitry is added in order to allow a phone to act as a dual-role USBOTG device. In
accordance with USBOTG requirements, the pull down resistors on UDP and UDM can be switched in or
out individually via SPI. Furthermore, the pulls down resistors are integrated on-chip.
The USBOTG specification requires that during the session request protocol, the D+ (full speed) line is
pulled up for a duration of 5 to 10 msec. In order to reduce the SPI traffic, the MC13783 has an integrated
timer used for this task.
To support VBUS pulsing, there is a programmable current limit and timer on the VBUS regulator. During
VBUS pulsing, the lower current limit allows for easier detection of a legacy host device on the far end of
the USB cable.
It is possible to have the transceiver automatically connect the data pull-up to VUSB any time a SE0 is
detected. This enables the phone to meet the USBOTG timing requirements without unduly taxing the
software.
Table 26. USB Mode Selection
USB Mode
Mode Selection Mode Description
Corresponding
UMOD0/UMOD1 Setting
DATSE0 BIDIR UTXENB = Low UTXENB = High
Differential
unidirectional
(6-wire)
0 0 UDATVP → UDP
USE0VM
→ UDM
UDP
→ URXVP
UDM
→ URXVM UDP/UDM
→ URCVD
Don’t Care /
To VAT LA S
bidirectional
(4-wire)
1 UDATVP → UDP
USE0VM
→ UDM
UDP
→ UDATVP
UDM
→ USE0VM UDP/UDM
→ URCVD
To VAT LA S /
To Ground
Single Ended
unidirectional
(6-wire)
10UDATVP→ UDP/UDM
USE0VM → FSE0
1
1
FSE0 stands for forced SE0, RSE0 stands for received SE0.
UDP
→ URXVP
UDM → URXVM UDP/UDM
→ URCVD
To Ground /
To Ground
bidirectional
(3-wire)
1 UDATVP → UDP/UDM
USE0VM → FSE0
UDP/UDM → UDATVP (active)
UDP → UDATVP (suspend)
RSE0 → USE0VM
Open /
To Ground