Automotive, 42V, synchronous buck controller with constant current and constant voltage with I2C

The LM25192-Q1 is a42V, high-efficiency,

synchronous buck controller with constant-current constant-voltage (CC-CV)

regulation and I2C interface.

The current-mode control architecture

with a 30ns typical minimum on-time allows high conversion ratios at high

frequencies coupled with a fast transient response and excellent load and line

regulation. The highly accurate CC-CV operation enables seamless transition between

constant-current and constant-voltage modes. The I2C interface allows

programming of output voltage in 10mV or 20mV steps, average output current limit in

50mA to 200mA steps, as well as output voltage slew rate, switching frequency,

soft-start slew rate, mode of operation, current loop compensation, output active

discharge strength, and cable drop compensation gain.

The LM25192-Q1 also features an array of safety features including

undervoltage and overvoltage protection with programmable thresholds, overcurrent

protection with programmable hiccup mode, and thermal shutdown.

Additional features of the LM25192-Q1 include programmable diode emulation(PFM)

for lower current consumption at light-load conditions, open-drain nINT flag for

fault reporting and output monitoring, precision enable input, monotonic start-up

into prebiased load, integrated dual input (VIN and VOUTF) VCC supply regulator, and

oversized VDDA regulator for powering external loads, such as companion

microcontrollers.

The LM25192-Q1 includes several features to simplify compliance with CISPR 25

emissions requirements. First, a symmetrical pinout provides excellent input

capacitor placement and enables an ultra-low effective value for the power-loop

parasitic inductance, which reduces switching losses and improves EMI performance at

high input voltage and high switching frequency. A pin-selectable switch-node

slew-rate control feature further reduces emissions at high frequencies. An I2C

programmable switching frequency as high as 2.2MHz can be synchronized to an

external clock source to eliminate beat frequencies in noise-sensitive applications.

Finally, the LM25192-Q1 has an I2C selectable ±5% dual-random spread spectrum

(DRSS) significantly reduces peak emissions through a combination of triangular

and pseudo-random modulation while keeping output voltage ripple very

low.

The LM25192-Q1 controller comes in a 3.5mm × 4.5mm thermally-optimized, 19-pin

QFN package. The large PGND die-attach pad improves thermal performance and board

level reliability (BLR). Also included are wettable-flank pins to facilitate optical

inspection during manufacturing. The 19-pin QFN packaging with useable current,

lifetime reliability, and cost advantages targets applications requiring high power

density. The wide input voltage range, low quiescent current consumption,

high-temperature operation, cycle-by-cycle current limit, low EMI signature, and

small design size provide an excellent point-of-load regulator design for

applications requiring enhanced robustness and durability.