LP3907SQ-JXQXEV National Semiconductor, LP3907SQ-JXQXEV Datasheet - Page 11

• 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: -

LP3907 HARDWARE BLOCK DESCRIPTION
The evaluation board is fully populated with the LP3907.
The LP3907 Evaluation board is designed to allow the user
to test each function independently as well as in the system.
Jumpers 1-6 as described in the Jumper table allow the VDD
and GND path of each of the blocks to be separated from the
rest of the blocks. To look at each of the blocks, follow the
instructions below:
1.
2.
3.
4.
5.
The output voltage of the Low dropout regulators can be ac-
cessed at the ‘Turrets’ (LDO1 and LDO2) referenced to
GND_M. These are marked on the silk screen of the evalua-
tion board.
Start with all the jumpers connected. (Without
USBPOWER, JP7 and JP8)
Use the provided GUI to disable the desired block.
Remove the connecting jumpers (JP1, JP2, JP4, or JP6)
based on the jumper table to isolate the power and
ground planes of the block under test.
Connect a power supply (V
desired block referenced to its corresponding ground.
Enable the block and proceed with normal testing.
OUT
+ 0.3V) to the input of the
FIGURE 11. Buck Regulator Feedback Network
11
The output voltage of the two Buck Regulators can be ac-
cessed at the ‘Turrets’ VBUCK1, VBUCK2 referenced to
GND_SW1, and GND_SW2.
External power supplies can be attached to VDD_M refer-
enced to GND_M. The voltage supplied to the system must
be between the range of 2.7V (with UVLO bypassed) to 5.5V.
SMB Connectors
The SMB connectors above VBUCK1 and VBUCK2 are con-
nected to the SW pin of Buck1 and Buck2, respectively. This
will allow the user to monitor the switching of the regulators.
Resistive Pull-ups
The two I
cessed externally via turrets I
are pulled up via 22K resistors R1, R2.
External Control Resistor Divider
Each of the Buck Switch Regulators has the option to be ex-
ternally compensated through the external resistive feedback
network shown in the figure below.
If the user wishes to have the chip internally compensated
with factory programmed settings, then a 0 ohm resistor
should be placed across R14 for Buck1 and R11 for Buck2.
2
C compatible signals SDA and SCL can be ac-
2
C SCL, and I
2
C SDA. Both lines
30017713
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