This application note summarizes a typical schematic and layout design for 24-channel LED driver, TPS929240-Q1, to achieve high BCI (Bulk Current Injection) immunity performance with test set-up and result analysis. The test is based on TPS929240-Q1 evaluation board, which passes international standard ISO11452-4 test level IV (200mA).
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The TPS929240-Q1 is a 24-channel, 40-V high-side automotive LED driver with FlexWire interface to address increasing requirements for pixel control of each LED string. Each of the device channels features various diagnostics including LED open-circuit, short-to-ground, single LED short-circuit detection and can support both analog dimming and PWM dimming. The internal user-programmable EEPROM allows automatic switching to FAIL-SAFE states in the case of communication loss to meet system level safety requirements. Figure 1-1 shows a typical application diagram.
Compared with traditional single ended interface, by using a CAN physical layer the UART-based FlexWire interface of the TPS929240-Q1 is much easier to accomplish long distance off-board communication without impacting EMC and BCI.