Datasheet
Using the Evaluation Software
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Figure 6. Chip Control Interface
6.3 Regulator Output Voltage Selection
The output voltages of all the LDO and buck converters can be programmed through I
2
C control registers
by simply moving the slider. The buck regulators have two sliders and a Hold/Ramp button to control its
output voltage. This prevents the user from scaling the bucks to the second voltage if the Hold/Ramp
button is not depressed. The output of the buck regulator will reflect the setting of the slider that has its
radio button clicked (V1 or V2).
The buck regulators also have a Hold/Ramp slider that determines how fast the regulators scale to the
2nd programmed voltage. The ramp time is measured from the time the chip receives the I
2
C signals from
clicking the opposing radio button.
All of the regulators can also be hardware enabled or disabled via different configuration settings on the
20 pin header (described in the Hardware section of this report). The buck regulators also have additional
enable test points on the board.
The user can also force the bucks into PWM mode. Clicking the Force PWM check box on the GUI forces
the respective regulator to stay in PWM mode even in the case of a light load (PFM mode). Forced PWM
will be disabled by clicking the “Force PWM” check-box again.
The buck converters have a slider interface to provide an adjustable output voltage. By sliding the bar to
the bottom of the slider, the user can use an external resistor divider network for setting the Bucks output
voltage.
Force PWM mode is not recommended when a battery is powering the system.
6
AN-1619 Evaluation Kit for LP3907 — Programmable Power Management SNVA233A–September 2007–Revised April 2013
Unit with 1
2
C Compatible Interface
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