Bipolar low dropout regulators (LDOs) have become common place in a variety of portable applications, such as cell phones, pagers and PDAs. Their popularity stems from small packaging, high output current capability and precision output voltage specifications. However, the bipolar process technology from which these devices are fabricated brings inherent disadvantages, such as excessive supply current. This application note outlines the advantages of small geometry CMOS LDOs over bipolar LDOs and provides comparative test data of key regulator specifications for a popular pin-compatible bipolar LDO over Microchip’s CMOS LDOs. M AN766 Pin-Compatible CMOS Upgrades to Bipolar LDOs Author: Don Alfano, Danny Alred, SUPPLY CURRENT: Abid Hussain and Paul Paglia, CMOS VS. BIPOLAR Microchip Technology Inc. Figure 1(A) and Figure 1(B) compare the block dia- gram for a common bipolar regulator with that of an INTRODUCTION equivalent regulator fabricated in CMOS. The supply current to the bipolar device is co……