LM25149 42 V Synchronous Buck DC/DC Controller

Texas Instruments' LM25149 is a 42 V, ultra-low I_Q synchronous buck DC/DC controller for high-current, single-output applications. The controller uses a peak-current-mode control architecture for easy loop compensation, fast transient response, and excellent load and line regulation. The LM25149 can be set up in interleaved dual-phase mode with accurate current sharing for high-current applications. The LM25149 has two unique EMI reduction features including an active EMI filter and dual random spread spectrum (DRSS).

The active EMI filter senses noise or ripple voltage on the DC input bus and injects an out-of-phase cancellation signal to reduce the disturbance. DRSS combines low-frequency triangular and high-frequency randomized modulations to mitigate EMI across lower and higher frequency bands, respectively. This hybrid technique aligns with the multiple resolution bandwidth (RBW) settings specified in industry-standard EMC tests.

Additional features of the LM25149 include user-selectable diode emulation for lower current consumption at light-load conditions, an open-drain power-good flag for fault reporting and output monitoring,  a precision enable input, monotonic startup into a prebiased load, an integrated V_CC bias supply regulator and bootstrap diode, internal 3 ms soft-start time, and thermal shutdown protection with automatic recovery. The controller is available in a 3.5 mm x 5.5 mm thermally-enhanced, 24-pin VQFN package with an exposed pad to aid in thermal dissipation. The device has a maximum operating junction temperature of +150°C.