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 you 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 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. After the new VADJ voltage
level has been programmed into TI controller U33, the FMC_VADJ_ON_B signal can be
driven Low by the user logic and the VADJ rail comes up at 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 I2C port expander U80 pin 13
(see Figure 1-18).
The I2C port expander IIC_PORT_EXPANDER SDA/SCL bus is wired to the PCA9548ARGER
I2C 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 decimal, U33 at address 53 decimal, and U34 at
address 54 decimal) 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
Digital Power Designer GUI
monitor the voltage and current values for the power rail listed in
and Table 1-33.
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 (v1.7) March 27, 2019
I2C Bus).
[Ref 25].
[Ref 27]. This is the simplest and most convenient way to
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Feature Descriptions
[Ref 26] and associated TI Fusion
Table 1-31, Table
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1-32,
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