JAJSJC6A December 2021 – June 2022 TPS92623-Q1
The TPS92623-Q1 device is a high-side current driver for driving LEDs. The device controls each output current through regulating the voltage drop on an external high-side current-sense resistor, R(SNSx) independently for each channel. An integrated error amplifier drives an internal power transistor to maintain the voltage drop on the current-sense resistor R(SNSx) to V(CS_REG) and therefore regulates the current output to target value. When the output current is in regulation, the current value for each channel can be calculated by using Equation 1.
When the supply voltage drops below total LED string forward voltage plus required headroom voltage, the sum of V(DROPOUT) and V(CS_REG), the TPS92623-Q1 is not able to deliver enough current output as set by the value of R(SNSx), and the voltage across the current-sense resistor R(SNSx) is less than V(CS_REG).