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Evaluation Software
3.1 Common Tab
Only one bit of the Enables register is controlled in the Common tab. The NSTBY bit controls the chip
on/off state.
The Common Tab contains also evaluation board control functions. Automatic writing (Update registers
immediately) is enabled by default. It means that a write operation is done after every mouse click. If you
want to change several settings in one or more tabs and write the register(s) after making all the changes,
you can disable automatic writing. Then after the changes you have to initiate the register write by clicking
the right mouse key with the cursor in the Register Map area. From the pop-up menu you can choose to
write all registers or just a selected register. The same pop-up lets you write default values to one or all
registers and read one or all registers.
After clicking the “Hardware reset” button, all register values will be reset to default value, and a pop-up
window appears where user can accept reading all the registers (this is recommended). Another way to
reset the chip is to disconnect the USB cable (or external power if it is used) for a few seconds, plug it in
again and read all registers to see that they have the default values after the power-on-reset. USB setup
button will restore default setting for USB interface board.
USB board can measure voltages from the evaluation board. On the LP5526 board the circuit VDDIO and
the converter output voltage VBOOST are measured. Measurements are enabled, when the Polling interval in
the Common tab is set. Measurement results are shown on top of the window.
The software can demonstrate external PWM brightness control using the GPIO[0]/PWM input. PWM
signal is generated by the software. External PWM can only reduce the brightness set by internal controls.
All the LEDs have enable bits (en_ext_X_pwm, en_main_pwm, en_sub_pwm) for allowing external PWM
control. These bits are controlled in corresponding LED control Tabs (Color LEDs and Backlight). External
PWM control has no effect to the outputs that do not have enable bit set. You must also set ‘en_pwm_pin’
bit in GPIO tab to set GPIO[0]/PWM pin act as an external PWM input pin.
Note that when Flash button (in Color LEDs Tab) is used and released, it resets the PWM pulse ratio. In
the Common Tab, the External PWM slider controls the duty cycle of the GPIO[0]/PWM input pin.
Measurement polling disturbs the External PWM control and it should be turned off when External PWM is
used.
3.2 Boost Tab
In this tab, Figure 3, the LP5526 boost converter can be enabled, and the output voltage can be set from
the pull-down menu. The internal active load can be enabled to eliminate pulse skipping of the boost
converter. Active load will consume some power when the boost output current is small. It will decrease
efficiency at very light load conditions. See datasheet for boost converter typical performance graphs.
Figure 3. Boost Tab
3
SNVA177B–January 2007–Revised April 2013 AN-1502 LP5526 Evaluation Kit
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