80-V synchronous buck DC/DC controller with ultra-low IQ and integrated active EMI filter

The LM5149 is a 80-V, ultra-low IQ

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 LM5149 can be set up in interleaved dual-phase mode with

accurate current sharing for high-current applications. The device can operate with

VIN as low as 3.5 V, at nearly 100% duty cycle if needed.

The LM5149 has two unique EMI reduction features: active EMI filter and dual random spread spectrum (DRSS). The active EMI filter senses any 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 LM5149 include 150°C maximum junction temperature

operation, user-selectable diode emulation for lower current consumption at light-load

conditions, open-drain power-good flag for fault reporting and output monitoring, precision

enable input, monotonic start-up into prebiased load, integrated VCC bias supply regulator

and bootstrap diode, internal 3-ms soft-start time, and thermal shutdown protection with

automatic recovery.

The LM5149- controller comes in a 3.5-mm × 5.5-mm thermally enhanced, 24-pin VQFN

package with an exposed pad to aid in thermal

dissapation.