ZHCSCK8G May 2014 – October 2017 LP8860-Q1
PRODUCTION DATA.
The power-line FET limits peak current from the power line during start-up and allows the boost and LED strings to be disconnected during a fault condition, when device is in fault recovery state.
The power-line control block has VSENSE_P and VSENSE_N pins for sensing input current and a shutdown SD pin for driving the gate of the power-line FET. The power-line FET is opened when the LP8860-Q1 is enabled by VDDIO/EN signal and VIN is greater than VGS in steady state (when pFET is used as a power-line FET). A power-line pFET must be chosen with minimal VGS in steady state. Gate current is defined by the <PL_SD_SINK_LEVEL[1:0]> EEPROM bits.
During a shutdown state the LP8860-Q1 closes the power-line FET and prevents possible boost and LED leakage. Sense pins are used to detect overcurrent. Power-line FET is closed when an OCP fault occurs. A VIN OCP is indicated with PL_FET_FAULT bit. The power-line FET closes with all faults, followed by entering to a recovery state.
When it is not possible to choose a pFET with the necessary characteristics, a schematic with nFET can be used (see Charge Pump section, Figure 25); the <NMOS_PLFET_EN EEPROM> bit must be set accordingly. In this case the SD pin provides current to shut down the power-line nFET during fault condition.