Maxim Integrated Products introduces the MAX5092 low-dropout (LDO) regulator with a boost preregulator. The device provides a regulated 3.3V (MAX5092A), 5V (MAX5092B), or adjustable output voltage from a 3.5V to 72V input voltage. This operating-input-voltage range allows for true buck-boost operation and provides uninterrupted power during key-off, cold-crank, and load-dump conditions in a harsh automotive environment. The MAX5092 reduces the size and cost of large bulk capacitors commonly used at the input of the electronic control units (ECUs) to ride through the "cold-crank" duration. The LDO regulator is capable of providing up to a 250mA output current, and it consumes only 65µA when the battery is healthy and the boost preregulator is completely turned off. In shutdown mode, the MAX5092's quiescent current drops to 5µA.

The boost preregulator output voltage is preset to 7V and can be externally adjusted up to 11V, while the LDO regulator output voltage can be adjusted from 1.5V to 9V. When the voltage at the input of the MAX5092 drops below the desired boost-converter output voltage, the boost converter is enabled and provides a boosted output voltage to power the LDO regulator. The buck-boost operation achieved by this combination of LDO and boost preregulator reduces component count and size, thus saving space and cost. This device integrates a blocking diode and needs no external boost converter. It also has a power-on-reset circuit with an externally programmable timeout period and includes output-overload, short-circuit, and thermal protection.

The MAX5092 is specified for operation over the -40°C to +125°C automotive temperature range and is available in a thermally enhanced, 5mm x 5mm, 16-pin TQFN package capable of dissipating 2.7W at an ambient temperature of +70°C. Prices start at $1.48 (1000-up, FOB USA).