Maxim Integrated Products has introduced two 40 V input, dual mode buck converters, the MAX5096/MAX5097, for automotive dc-dc applications.

Operating over the -40 °C to 125°C automotive temperature range, the devices feature a user-selectable low-dropout (LDO) mode. At a high-output load they reduce power dissipation by operating as high-efficiency, pulse-width modulated (PWM) switch-mode buck converters. During a key-off condition, the system microcontroller drives the LDO or BUCK input pin on-the-fly and forces the change to LDO mode; reducing quiescent current. In LDO mode at a 100 µA load, quiescent current is 41 µA.

In buck mode, the MAX5096/MAX5097 operate from a 5 V to 40 V input-voltage range and deliver up to 600 mA of load current. In LDO mode, for output load currents up to 100 milliamps, the converters operate from a 4 V cold crank to 40 V input voltage.

The devices operate at a fixed-switching frequency of 135 kHz (MAX5096) or 330 kHz (MAX5097). Their internal dc-dc converter clock can be synchronized to an external clock. Both devices use external compensation, which allows the use of low-cost inductors and output capacitors while optimizing loop stability.

Additional features include current-mode control for ease of design, power-on reset output with a capacitor-adjustable timeout period, programmable soft-start, output tracking, output overload, and short-circuit/ thermal-shutdown protections. The converters are available in thermally enhanced 20-pin TSSOP and 16-pin TQFN packages.