8.3.1 Control Interface
Device control interface includes:
- EN is the enable input for the LP8863-Q1 device.
- INT is an open-drain fault output (indicating fault condition detection or thermal threshold crossing).
- IFSEL is used for selecting between I2C and SPI.
- SPI is a 4-wire interface using SCL, SDI, SDO, and SS pins.
- When SPI is selected the brightness must be controlled using the DISP_BRT and BRT_MODE registers.
- I2C is a 2-wire interface using SCL and SDA pins.
- When I2C is selected, the ADDRSEL pin is used to select between two alternate slave addresses.
- When I2C is selected, the BRT_MODE register setting is used to select whether the brightness is controlled by the DISP_BRT register or PWM input pin. The PWM pin is selected by default so that an I2C interface is not required.
- BST_SYNC is used to input an external clock for the boost switching frequency and control the internal boost clock mode.
- The external clock is auto detected at start-up and, if missing, the internal clock is used.
- Optionally, the BST_SYNC can be tied to VDDIO to enable the boost spread spectrum function or tied to GND to disable it.
- ISET pin to set the maximum LED current level per string.
- BST_FSET pin to set the boost switching frequency.
- PWM_FSET pin to set the LED output PWM dimming frequency.
Control interface is selected with IF_SEL pin according to Table 1.
Table 1. Control Interface Selection, SPI or I2C
IF_SEL |
SERIAL INTERFACE |
VDDIO (1) |
I2C |
GND (0) |
SPI |
In I2C mode the ADDRSEL is used to select between two unique slave addresses, and the PWM input may be used to control the brightness.