Datasheet
Using the Evaluation Hardware
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Figure 12. Jumper Settings to Disable All Regulators and EN_T
7.3 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. Start with all the jumpers connected. (Without USBPOWER, JP7 and JP8)
2. Use the provided GUI to disable the desired block.
3. 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.
4. Connect a power supply (V
OUT
+ 0.3V) to the input of the desired block referenced to its corresponding
ground.
5. Enable the block and proceed with normal testing.
The output voltage of the Low dropout regulators can be accessed at the ‘Turrets’ (LDO1 and LDO2)
referenced to GND_M. These are marked on the silk screen of the evaluation board.
The output voltage of the two Buck Regulators can be accessed at the ‘Turrets’ VBUCK1, VBUCK2
referenced to GND_SW1, and GND_SW2.
External power supplies can be attached to VDD_M referenced 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 connected 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
2
C compatible signals SDA and SCL can be accessed externally via turrets I
2
C SCL, and I
2
C
SDA. Both lines are pulled up via 22K resistors R1, R2.
External Control Resistor Divider
Each of the Buck Switch Regulators has the option to be externally compensated through the external
resistive feedback network shown in Figure 13.
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.
10
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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