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Automotive LDO runs without a glitch from cold-crank to load-dump

Sunnyvale, Calif.&#8212Maxim's MAX5092 low-dropout (LDO) regulator with boost preregulator, for harsh automotive environments and always-on supplies, facilitates true buck-boost operation, thus providing uninterrupted power from cold-crank (4 volts) through the 72-volt load-dump condition.

The buck-boost topology of LDO and boost preregulator offers designers the advantage of using a single off-the-shelf inductor in place of the multiple-winding custom magnetics needed in typical single-ended primary inductor converter (SEPIC) and transformer-based flyback topologies. The design also reduces the cost and size of the bulk capacitors commonly used at the input of the electronic control units (ECUs) to ride through the “cold-crank” duration. The boost regulator's high operating frequency significantly reduces component size; in addition, the chip integrates a blocking diode.



The LDO, providing a fixed 3.3 or 5 volts (MAX5092A, MAX5092B, respectively) or adjustable 1.5 to 10-volt output (MAX5093) can deliver up to 250 mA, with quiescent current at just 65 microamps (boost regulator off). In shutdown mode, the MAX5092's quiescent current drops to 5 microamps. The boost preregulator output voltage is preset to 7 volts and can be adjusted up to 11 volts. The boost-converter kicks in when the input voltage drops below the user's preset level, and powers the LDO regulator. The device also features power-on-reset circuitry with an externally programmable timeout period and includes output-overload, short-circuit, and thermal protection.

Click here for the product datasheet. The MAX5092, in a 5-by-5 mm, 16-pin TQFN and specified for operation over -40 to +125°C is priced at $1.48 each (1000-up, FOB USA).

Maxim , 1-800-998-8800, www.maxim-ic.com

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