EVAL-ADP8860
Rev. 0 | Page 14 of 24
EVALUATION BOARD OVERVIEW
MOTHERBOARD
INT/EXT SUPPLIES
JUMPER SELECTION
VBATT LED
INDICATOR
VDDIO LED
INDICATOR
VBOARD LED
INDICATOR
RESET (nRST)
PUSHBUTTON
EXTERNAL
TARGET
CONNECTOR
BACKLIGHT LEDS (7 MAXIMUM) AND
INDIVIDUAL JUMPERS SELECTION
BACKLIGHT/KEYPAD
LED SELECTION JUMPER
KEYPAD LEDS (10 MAXIMUM) AND
INDIVIDUAL JUMPERS SELECTION
(UP TO THREE CURRENT LEVELS)
PHOTOTRANSISTORS
BIAS VOLTAGE JUMPER
SELECTION
07
98
8-
0
29
EXTERNAL SUPPLIES
USB CONNECTOR
DAUGHTER BOARD
CONNECTORS
Figure 29. Motherboard
The EVAL-ADP8860 motherboard provides the interface
signals to the ADP8860 parallel backlight IC. These include
the SDA and SCL lines for I
2
C or the control line voltages for the
hardware interface modes (nRST and nINT).
The CY68013A from Cypress Semiconductor Corporation
provides the USB interface and I
2
C signals. The selected I
2
C
frequency is 100 kHz. The M24C64R serial EEPROM provides
the USB address of the board. The interface voltage is selected
with the VBOARD header on the board and is set to 3.3 V by
default.
Typically, the daughterboard is inserted directly into the 2 × 20
pin header of the motherboard. The 8-pin header, J29, on the
top of the motherboard can be used to connect external supplies.
The
VBATT OKAY
,
VDDIO OKAY
, and
VBOARD OKAY
LEDs located at the top left of the board light up when the
board is powered from the USB cable or external supplies are
connected to J29 and the LK1 to LK3 jumpers are set in the
EXT
position. It is possible to choose several supply combi-
nations. For example VBOARD, which supplies the motherboard
ICs, can be provided from the USB while VDDIO and VBATT
are provided externally. The motherboard contains three LDOs,
generating the default supply voltage as indicated in Table 1.
Table 1. Power Supply Options
Supply Line
LK8 to LK10 in
USB Position
LK8 to LK10 in
EXT Position
VBATT
Internal: 3.7 V
External: 2.3 V to 5.5 V
VDDIO
Internal: 2.7 V
External: 1.7 V to 5.5 V
VBOARD
Internal: 3.3 V
External: 2.7 V to 3.6 V
Jumper LK4 selects the supply voltage for the daughterboard
phototransistors. With the jumper in EXT_VS position, the supply
vVS comes from the external target. With the jumper in
VBOARD position, +VS is supplied by the VBOARD rail.
