Xilinx Virtex-7 VC7222 User Manual page 42

Chapter 1: VC7222 Board Features and Operation
XADC
Callout 37,
The 7 series FPGAs provide an Analog Front End (XADC) block. The XADC block includes
a dual 12-bit, 1 MSPS Analog-to-Digital Convertor (ADC) and on-chip sensors. See 7 Series
FPGAs and Zynq-7000 All Programmable SoC XADC Dual 12-Bit 1 MSPS Analog-to-Digital
Converter User Guide (UG480)
The VC7222 board provides two options for providing power (VCCADC) to the analog
circuitry in the XADC. Either option can be selected by placing a shunt in one of two
positions on the 3-pin VCCADC SELECT header, J141 (callout 31,
•
•
In addition, the VC7222 board provides two options for providing the reference voltage for
the analog-to-digital converter. Either option can be selected by placing a shunt in one of
two positions on the 3-pin VREF SEL header J142 (callout 31,
•
•
I2C Bus Management
The I2C bus is controlled through U39, an 8-channel I2C-bus multiplexer (NXP
Semiconductor PCA9547). The FPGA communicates with the multiplexer through I2C
data and clock signals mapped to FPGA pins AG24 and AF24, respectively. The I2C idcode
for the PCA9547 device is 0x70. The bus hosts four components:
•
•
•
•
•
An I2C component can be accessed by selecting the appropriate channel through the
control register of the MUX as shown in
Table 1-22: I2C Channel Assignments
42
Send Feedback
Figure 1-2.
Pins 1-2 (VCCAUX): In this configuration VCCADC is provided from VCCAUX
through a low pass filter network.
Pin 2-3 (REG): In this configuration VCCADC is provided by an onboard regulator,
U43 (Analog Devices P/N ADP123AUJZ-R7). The output voltage of the regulator
VCCADC can be adjusted using the potentiometer R233.
Pins 1-2 (REG): In this configuration the ADC reference voltage is provided by an
onboard, low-temperature coefficient 1.25V reference, U45 (Texas Instruments P/N
REF3012AIDBZT)
Pin 2-3 (AGND): In this configuration the VREFP on XADC is connected to analog
ground and the ADC uses an on-chip reference.
SuperClock-2 module
7 series GTH transceiver power supply module
7 series GTZ transceiver power supply module
FMC1
FMC2
U39 Channel
0 SuperClock-2 module
1 7 series GTH transceiver power supply module
2 FMC1
3 FMC2
4 7 series GTZ transceiver power supply module
www.xilinx.com
[Ref 1] for details on the capabilities of the analog front end.
Table 1-22.
I2C Component
VC7222 Transceiver Characterization Board
Figure 1-2):
Figure 1-2):
UG965 (v1.4) February 11, 2015