Freescale Semiconductor
MCIMX53SMD Board Hardware User’s Guide, Rev. 0
45
The i.MX53 processor has an internal method and an external method to measure Band Gap resistance. If the
internal method is chosen by the software, pin AA14 can be left floating. If the external method is desired, a
28.0K 1%Ω resistor should be attached between pin AA14 and ground. It is recommended to add this resistor
routinely to give software the option of choosing between the two methods. It is also recommended to place
a 49.9 1%Ω resistor as the voltage input pin of U14 (NVCC_LVDS_BG) to filter the power used in measuring the
Band Gap resistance.
5.10.
Expansion Port
The function of the MCIMX53SMD board Expansion Port is to bring out many of the i.MX53 pins that are
otherwise unused on the MCIMX53SMD board. The overriding design considerations for this port were to be
able to support HDMI functionality through a daughter card (primary), while also being able to support an
existing LCD daughter card (secondary). In meeting these considerations, the Expansion Port was also
constrained to meet a general power/signal format adopted across all recent i.MX development board
designs, primarily for safety and equipment damage consideration. For these reasons, there may be some
functionalities of the i.MX53 chip that are not accessible on the MCIMX53SMD board.
For developers who are interested in designing custom daughter cards to be used with the MCIMX53SMD
board, the following capabilities are available from the Expansion Port. Note that many pins are muxed, so
that not all features are available at the same time:
Two Serial Peripheral Interfaces (SPI)
CSPI, eCSDPI2
Two I2S/SSI/AC97 Ports
AUDMUX4, AUDMUX5
Two Inter-Integrated Circuits (I2C)
I2C1, I2C2
2 UARTs
UART4, UART5
SPDIF Audio
USB ULPI Port
USBH2
24-bit Data and display control signals
Resistive Touch Screen Interface
In addition to the Data/Signal traces to support the above functionality, the following power sources are also
included on the Expansion Port:
5V_MAIN
5V
DCDC_5V
LCD_3V3
3.3V
DCDC_3V3
VIOHI_2V775
2.775V
VLDO4
VLDO8_1V8
1.8V
VLDO8
VLDO9_1V5
1.5V
VLDO9
VLCD_BLT
Current Source
PMIC LED Driver
Note that VLDO9 is only used by the Expansion Port on the MCIMX53SMD board. The developer is free to
reprogram the LDO regulator on the PMIC for desired voltage with these limitations:
Voltage
1.25V – 3.6V
Current
100 mA
A suitable connector to be used with Expansion Port J13 is one developed by Samtec, QTH-060-XX-L-D-A,
where XX determines the height of the connector. See the
available pin-mux options.
5.11.
Audio
The main Audio CODEC used on the MCIMX53SMD board is the Freescale SGTL5000 Low Power Stereo Codec
with Headphone Amp. The i.MX53 processor provides digital sound information from the AUDMUX module
