Demonstration circuit DC2247A is a synchronous 2MHz boost LED driver featuring the LT®3922. The LT3922 features a low EMI Silent Switcher architecture and an optional spread spectrum frequency modulation (SSFM) that further reduces EMI. It has a 2A/36V internal power switch, but the demo board has been configured to use a 4V to 28V input and thus has input overvoltage lockout set at 28V. It drives a single string of LEDs at 330mA up to 34V when the input voltage is between 7V and 28V.
DC2247A comes with low EMI features including optimized layout, SSFM, and input and output filters. It passes CISPR 25 class 5 conducted and radiated EMI. The LT3922 is protected against both open and short LED conditions and reports these faults. It also includes thermal shutdown.