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1.1
Voltage Reference
1.2
EVM Operation
Hardware Overview
Windows-based PC
•
LEDs for board power and power supply enables for quick visible indication of power supply status
•
Eight onboard LDOs and power supplies for sequencing and monitoring testing
The eight power supplies, provided on the UCD9080EVM, are a combination of low-dropout regulators
(LDO), power converter ICs, and power converter modules, all from Texas Instruments.
Rails 1-6 have a TI TPS76901 LDO for generating voltages from 1.4 V to 2.4 V. Rail 7 has a TI PTH04070
switching power supply IC for generating a 2.6 V output. Rail 8 has a TI PTH05050 power module used
for generating a 2.8 V output. This set of power supplies are provided for generating different output
voltages on the board for testing of different sequencing and monitoring conditions.
Users can communicate with the board using the I
2
C protocol through the supplied USB Interface Adapter
and GUI. The GUI helps users to change the sequencer configuration, plus monitor voltage and device
status from a Windows PC.
Because the UCD9080 monitors analog signals (voltage), its ability to accurately convert the value of the
rail voltages to digital values (for conversion to volts for the user) is a function of the quality of the voltage
reference on the device.
The UCD9080 IC can run in one of two modes: internal reference or external reference (selectable via the
GUI). When operating with the internally generated 2.5-V reference, the sampling accuracy is not as good
as is possible with the external reference (see data sheet
for details). If measuring voltage
accurately to 5 mV is not required, then the internal reference is sufficient.
If the application requires better voltage monitoring accuracy, then the external reference (derived from the
UCD9080 VCC pin) should be used. This EVM uses a shunt regulator that produces a clean 3.3-V supply
voltage to the UCD9080. This regulator is only required to supply the UCD9080 VCC pin if the voltage
reference is set to internal.
The default behavior of the device (and EVM) is for an external voltage reference.
The UCD9080EVM requires power from an AC wall adapter through J1 or from a laboratory power supply
through J5. This provides 5 V to power the LEDs, power supplies, and the UCD9080 (using a 3.3-V board
regulator). The UCD9080 begins operation as soon as power is applied to the EVM. The UCD9080EVM
has several LEDs to indicate board power and active enables for each onboard power supply.
Connect the power source to the board and enable the power source. The red LED labeled D4 illuminates
to indicate that the board has power . You should then observe D1 and D5–D11 illuminate, indicating the
application is running.
Next, connect the USB interface adapter to the UCD9080EVM via the provided ribbon cable. Plug the
USB cable into the adapter and the other end into your PC. Instructions about how to run the GUI appear
in a later section in this document.
Before power up, remove the jumper JP29. This jumper disconnects the I
2
C addresses from being
changed during start-up. (This is one of the signals that the UCD9080 uses to detect and learn its I
2
C
addresses.)
2
UCD9080 Power Supply Sequencer and Monitor Evaluation Module
SLVU184A – March 2007 – Revised February 2008
