Datasheet

The register addresses are shown with the register names in the boxes surrounding the controls. The minimum
procedure for turning on the LEDs is as follows:
1. Connect the LED board to the LP8556 evaluation board. Set jumpers for number of LEDs per string.
2. Connect external power and ground to the board.
a. Suggest 3.6V to VIN jack.
b. Suggest 3.3V to VDDIO jack.
c. Connect Ground to GND jack.
3. Jumper on P2 VDD to VIN
4. Jumper on P6 I2C PU to VUSB
5. Turn on the external supplies.
6. Connect interface board to computer USB port.
7. Run LP8556A.exe
8. Change the Mode in the dropdown box under Brightness Mode and Control Registers 00 and 01 to Brightness
register only.
9. Check the Enable Backlight box.
10. Move the slider under Brightness Mode and Control Registers 00 and 01 to increase the current provided to the
LEDs
The 02 Status Register will update every time the Readback All button is pressed. The status register should show
VRef OK and VBoost OK checked indicating normal operation after the steps listed above are performed and the
Readback All button is pressed.
Access to any register is available through the Manual Control on the lower right.
See the LP8556 datasheet for detailed descriptions of the registers and their usage.
NOTE: Do not change the configuration of the device while the backlight is enabled. First disable the backlight by
making sure Enable Backlight is unchecked. Then adjust the configuration and turn on the backlight. Changing
the configuration while the backlight is on may produce unexpected results.
NOTE: If the part is enabled to any level of brightness or state and the program is closed, the LP8556 device will
remain in the last controlled state.