New Industry Products

National Semi Intros Dual-Rail Linear Regulators

April 20, 2003 by Jeff Shepard

National Semiconductor has added two CMOS dual input low dropout (LDO) voltage regulators that claim to offer the industry’s lowest dropout. Optimized for low-voltage, high current applications in PCs and set-top boxes, this new family of LDOs enables high efficiency linear conversion while consuming ultra-low quiescent current of only 3 mA under all conditions. In contrast, the quiescent current of bipolar alternatives increases to over 100 mA as the regulator approaches dropout.

"The ultra-low dropout of 160 mV and ultra-low quiescent current make National’s LP3881 the industry’s most power efficient LDO in applications generating a regulated 1.5 V output from a 1.8 V input," said Paul Greenland, marketing director of National Semiconductor’s Power Management Group. "With the LP388x family, designers now have a linear alternative to complex, noisy switching regulators when generating output voltages down to 1.2 V."

The LP388x family now includes the two new devices, the LP3881 and LP3882, and the recently released LP3883, providing a significant power savings to customers. This family uses a separate input to power the control circuitry; the power input may be fed independently from the high current supply facilitating conversion from input rails of less than 2.5 V. The CMOS dual input architecture allows for an ultra low input voltage and low output voltages down to 1.2 V. The dropout voltage for the LP3883/2/1 is typically 210 mV/110 mV/75 mV at 3 A/1.5 A/0.8 A and a maximum of 420 mV/270 mV/160 mV over temperature, the best in the industry.

The LP388x family’s unique circuit approach enables delivery of custom voltages in 50 mV increments in the range of 1.25 V to 1.8 V. The LP388x family has an output voltage accuracy of +/-3 percent over line, load and temperature variations and features on/off control, over-temperature and over-current protection.

National Semiconductor’s LP388x family of high current, low voltage CMOS LDOs is shipping. Offered in TO220-5 lead and TO263-5 lead packages. In 1,000-unit quantities, the LP3881 is priced at $2.08 each, the LP3882 is priced at $2.18 each and the LP3883 is priced at $2.68 each.