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SLUUBM0 – May 2017
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TPS92518EVM Dual Buck Controller Evaluation Module
Quick Start:
Provide input power of 6.5 V to 65 V to VIN, provide LED loads with output voltages of
between 2 V and 64 V to the two output channels. Next click on the
TPS92518 Enabled
box so it is
checked, then on the
Buck 1 Enable:
and
Buck 2 Enable:
boxes so they are checked. The integrated
circuit should start switching on each channel and regulating current to the LED loads.
Design Customization and GUI Operation:
Access to key TPS92518 registers is provided via the GUI
main window. Each channel
Peak Threshold
,
Off Time
and
Maximum Off-time
can be adjusted using
the respective slider. Minimum limits are enforced in the GUI for the Off-Time and Maximum Off-time as
these values should not be set <10 except under specific and controlled conditions. (see the datasheet
section: Off-Time Thresholds - LEDx_TOFF_DAC and LEDx_MAXOFF_DAC) The registers can still be set
manually to lower values via the SPI Command section of the GUI. The sliders can be moved and the
affect on the output current and switching frequency observed.
For a specific design configuration, the
Design Tool
button can be selected. This opens a simple
TPS92518 design calculator window. Design Parameters can be entered and adjusted. Component and
register values will be calculated. This calculator can be used to aid in any TPS92518 design, and is not
just for use with the EVM.
For each slider adjustment an estimation of the relevant parameter value is also shown. For the peak
current estimate, the value of the sense resistor can be set in the area below the sliders. (default is the
actual EVM value of 0.15 Ohms) The estimated off-time and maximum off-times are also updated and
reflect the current LED output voltage as measured by the TPS92518x internal ADC.
In the GUI
Control
section, the TPS92518 enable pin voltage can be controlled via the enable check box.
The GUI also provides the ability to create PWM dimming signals. A PWM duty cycle and frequency can
be set creating the corresponding signal at the TPS92518 PWMx pin. In normal operation the PWM duty
cycle must be left at 100% to disable PWM dimming.
Registers may also be written manually via the
SPI Command
section. By using the TPS92518 datasheet
Registers
section as a guide, specific registers can be manually read and written. To preform a register
write, set the write check-box. Un-check the box for a read. When reading and writing manually it is best
to disable the
Auto Refresh
of the registers by toggling the feature via the 'Auto Refresh' box. Once the
register value and write data (if applicable) are set, select the
Send Command
button. Due to the nature of
a SPI bus operation, read commands must be sent twice; once to load the read command and another
time to clock out the requested data.
