L4947屬于集成電路（IC）的線性+開關(guān)穩(wěn)壓器。由意法半導體集團制造生產(chǎn)的L4947穩(wěn)壓器 - 線性線性穩(wěn)壓器用于提供穩(wěn)定的輸出電壓，無論負載電流、輸入電壓或環(huán)境因素如何變化，這些輸出電壓通常都要保持不變。它們的工作原理要求輸入電壓維持在高于所需的輸出電壓，而且要超出某個最小量，并且在工作時會將輸入端的任何多余電壓轉(zhuǎn)換為熱量。對于大多數(shù)應(yīng)用而言，雖然這種穩(wěn)壓器的效率低于開關(guān)模式的穩(wěn)壓器，但它們通常更適合對噪聲高度敏感的應(yīng)用。

DESCRIPTION

The L4947/L4947R is a monolithic integrated circuit in Pentawatt package specially designed to provide a stabilized supply voltage for automotive and industrial electronic systems. Thanks to its very low voltage drop, in automotive applications the L4947/L4947R can work correctly even during the cranking phase, when the battery voltage could fall as low as 6V. Furthermore, it incorporates a complete range of protection circuits against the dangerous overvoltages always present on the battery rail of the car. The reset function makes the device particularly suited to supply microprocessor based systems : a signal is available (after an externally programmable delay) to reset the microprocessor at power-on phase ; at power-off, this signal becomes low inhibiting the microprocessor.

■ PRECISE OUTPUT VOLTAGE (5V ± 4) OVER FULL TEMPERATURE RANGE (– 40 / 125 °C)

■ VERY LOW VOLTAGE DROP (0.75Vmax) OVER FULL T RANGE

■ OUTPUT CURRENT UP TO 500mA

■ RESET FUNCTION

■ POWER-ON RESET DELAY PULSE DEFINED BY THE EXTERNAL CAPACITOR

■ + 80V LOAD DUMP PROTECTION

■ – 80V LOAD DUMP PROTECTION

■ REVERSE VOLTAGE PROTECTION

■ SHORT CIRCUIT PROTECTION AND THER MAL SHUT-DOWN (with hysteresis)

■ LOW START UP CURRENT