MCIMX281AVM4B Freescale Semiconductor, MCIMX281AVM4B Datasheet - Page 2035

• Manufacturer Part Number: MCIMX281AVM4B
• Description: IC MPU I.MX28 1.2 289MAPBGA
• Manufacturer: Freescale Semiconductor
• Series: i.MX28r

Specifications of MCIMX281AVM4B

• Core Processor: ARM9
• Core Size: 32-Bit
• Speed: 454MHz
• Connectivity: CAN, EBI/EMI, Ethernet, I²C, MMC, SmartCard, SPI, SSI, UART/USART, USB OTG
• Peripherals: DMA, I²S, LCD, POR, PWM, WDT
• Program Memory Size: 128KB (32K x 32)
• Program Memory Type: Mask ROM
• Ram Size: 32K x 32
• Voltage - Supply (vcc/vdd): 1.25 V ~ 5.25 V
• Data Converters: A/D 17x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 289-LFBGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of I /o: -
• Eeprom Size: -
• Lead Free Status / Rohs Status: Supplier Unconfirmed

Chapter 32 Integrated USB 2.0 PHY
32.2.4.7 Single-Ended USB_DN Receiver
The single-ended USB_DN receiver output is high whenever the USB_DN input is above
its nominal 1.8 V threshold.
32.2.4.8 9X Oversample Module
The 9X oversample module uses nine identically spaced phases of the 480 MHz clock to
sample a high speed bit data. The squelch signal is sampled only 1X.
32.2.5 Analog Transmitter
The analog transmitter comprises two differential drivers: one for high-speed signaling and
one for full-speed signaling. It also contains the switchable 1.5 K pullup resistor. See
Figure
32-2.
32.2.5.1 Switchable High-Speed 45 Termination Resistors
High-speed current mode differential signaling requires good 90 W differential termination
at each end of the USB cable. This results from switching in 45
terminating resistors
from each signal line to ground at each end of the cable. Because each signal is parallel
terminated with 45
at each end, each driver sees a 22.5
load. This is much too low of
a load impedance for full-speed signaling levels hence the need for switchable high-speed
terminating resistors. Switchable trimming resistors are provided to tune the actual
termination resistance of each device, as shown in
Figure
32-3. The
HW_USBPHY_TX_TXCAL45DP bit field, for example, allows one of 16 trimming resistor
values to be placed in parallel with the 45 terminator on the USB_DP signal.
32.2.5.2 Low-Speed/Full-Speed Differential Driver
The Low-Speed/full-speed differential drivers are essentially "open drain" low-impedance
pulldown devices that are switched in a differential mode for low-speed or full-speed
signaling, that is, either one or the other device is turned on to signal the "J" state or the "K"
state. The tx_ls_en signal is used to select the USB_DP/USB_DN edge for low-speed or
full-speed. Setting this bit to 1 selects the low-speed driver; otherwise the full-speed driver
is selected. These drivers are both turned on, simultaneously, for high-speed signaling. This
has the effect of switching in both 45
terminating resistors. The tx_fs_hiz signal originates
in the digital transmitter section. The hs_term signal that also controls these drivers comes
from the UTMI.
i.MX28 Applications Processor Reference Manual, Rev. 1, 2010
Freescale Semiconductor, Inc.
2035