DLPS039F December 2015 – April 2019 TPS99000-Q1
PRODUCTION DATA.
The TPS99000-Q1 includes a dedicated ADC channel for LED current measurement. The blanking current management process in system software, described in the Continuous Mode Operation section, relies on this measurement to coordinate the blanking current to the photo feedback current. The software measures the actual LED current in photo feedback (per color) and also measures the blanking current. The blanking current setting is fine trimmed during system operation to a level ideal for optimizing the initial current of each light pulse. As such, it is critical to system performance that this LED current measurement is as noise free as practical. Using a Kelvin connection to the low side sense resistor, and an RC filter is recommended to filter switching ripple, as illustrated in Figure 43. The Kelvin resistors should be < 100 Ω each and should have a tolerance of less than 0.5% matched resistors.