LP3907SQ-JXQXEV National Semiconductor, LP3907SQ-JXQXEV Datasheet - Page 5

• Manufacturer Part Number: LP3907SQ-JXQXEV
• Description: LP3907 EVALUATION BOARD
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LP3907SQ-JXQXEV

• Main Purpose: DC/DC, Step Down with LDO
• Outputs And Type: 4, Non-Isolated
• Current - Output: 1A, 600mA, 300mA, 300mA
• Regulator Topology: Buck
• Frequency - Switching: 2.1MHz
• Board Type: Fully Populated
• Utilized Ic / Part: LP3907
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Output: -
• Voltage - Input: -
• Power - Output: -

Using the Evaluation Software
REGISTER INTERFACE (DIRECT WRITE AND READ)
A register control established through an I
interface allows the user to directly program the registers by
writing to and reading from the memory map registers. This
provides the user with added flexibility in controlling the dif-
ferent functions of the LP3907. However, we caution the user
to use this function only for debugging purposes, because
sending wrong values could damage the part. Sliders and
buttons provided below will accomplish the same commands
in a more interactive way, and is also less prone to mistakes.
USING THE REGISTER CONTROLS
Direct Register Access (left section of Fig. 5) is divided into
two parts: Direct Register Write on the left and Direct Register
Read on the right. To write to a specific register, simply type
CHIP CONTROL INTERFACE
If the IC changes state and/or if the user assigns a new value
to a register, the GUI may not reflect those changes if the
“Auto Poll” button is not enabled. By hitting the “Read All”
button, the user will manually renew the GUI so that it reflects
the most current state of the IC.
The “Auto Poll” check box refreshes the GUI every second to
ensure that it mirrors the current state of the chip. The check-
box is on by default so that the user can constantly monitor
the status of the IC. Similarly, the “Auto Write” check box will
2
C compatible serial
FIGURE 6. Chip Control Interface
FIGURE 5. Register Interface
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the register address in hexadecimal into the box, set the value
through the specific bit buttons, and click “Write”. To read a
value in binary, type in the register address in hexadecimal
into the box on the right and click “Read”.
For example, to turn off all regulators except the LDO1 regu-
lator, this could be done by typing in the number 10 into the
“Addr (HEX):” box, clicking binary placeholder number 4, and
then clicking store. The register should reflect the stored value
assigned (00010000) when the user clicks the button “Read.”
Please note that the same function could be more easily im-
plemented through the graphical interfaces, and is in the
users’ best interest use Direct Register Access only when
necessary.
The register profile interface allows the user to save all his/
her settings for use at a later time. The GUI is programmed
to accommodate saving two sets of profiles.
enable the signals generated from using the sliders or buttons
to be sent to the chip. The check box is on by default, and
should be unchecked if the user wishes not to change the
settings on the chip.
The “Defaults” button will set all registers on the chip to the
default settings when clicked. The “Measure” button will up-
date the values measured on the chip by ADCs on the USB
interface.
The Quit button allows the user to exit the program.
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