Vadj Voltage Control; Monitoring Voltage And Current - Xilinx ZC702 User Manual

VADJ Voltage Control

The VADJ rail is set to 2.5V. When the ZC702 board is powered on, the state of the
FMC_VADJ_ON_B signal wired to header J12 is sampled by the TI UCD9248 controller U33.
If a jumper is installed on J12 signal FMC_VADJ_ON_B is held low, and the TI controller U33
energizes the VADJ rail at power on.
Because the rail turn on decision is made at power on time based on the presence of the J12
jumper, removing the jumper at J12 after the board is powered up does not affect the 2.5V
power delivered to the VADJ rail and it remains on.
A jumper installed at J12 is the default setting.
If a jumper is not installed on J12, signal FMC_VADJ_ON_B is high, and the ZC702 board
does not energize the VADJ 2.5V at power on. In this mode the user can control when to
turn on VADJ and to what voltage level (1.8V, 2.5V or 3.3V only). With VADJ off, the XC7Z020
AP SoC still configures and has access to the TI controller PMBUS along with the
FMC_VADJ_ON_B signal. The combination of these allows the user to develop code to
command the VADJ rail to be set to something other than the default setting of 2.5V. Once
the new VADJ voltage level has been programmed into TI controller U33, the
FMC_VADJ_ON_B
the new VADJ voltage level. Installing a jumper at J12 after a ZC702 board powers up in this
mode turns on the VADJ rail.
The FMC_VADJ_ON_B signal is sourced by the TCA6416APWR I
(see Figure 1-18, page
2
The I C port expander IIC_PORT_EXPANDER SDA/SCL bus is wired to the PCA9548ARGER I
bus switch (see
Documentation describing PMBUS programming for the UCD9248 digital power controller
is available at TI

Monitoring Voltage and Current

Voltage and current monitoring and control are available for selected power rails through
Texas Instruments' Fusion Digital Power graphical user interface. The three onboard TI
power controllers (U32 at address 52, U33 at address 53, and U34 at address 54) are wired
to the same PMBus. The PMBus connector, J59, is provided for use with the TI USB Interface
Adapter PMBus pod (TI part number EVM USB-TO-GPIO, which can be ordered from the
Texas Instruments website
[Ref 28]. This is the simplest and most convenient way to monitor the voltage and current
values for the power rail listed in
In each of these the three tables (one per controller), the Power Good (PG) On Threshold is
the setpoint at or above which the particular rail is deemed "good". The PG Off Threshold is
the setpoint at or below which the particular rail is no longer deemed "good". The controller
ZC702 Board User Guide
UG850 (v1.3) June 4, 2014
signal can be driven low by the user logic and the VADJ rail comes up at
39).
I2C Bus, page 36).
[Ref 26].
[Ref 27] and associated TI Fusion Digital Power Designer GUI
Table
www.xilinx.com
1-31, Table 1-32, and Table
Feature Descriptions
2
C port expander U80 pin 13
1-33.
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C
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