Dual-rail CMOS LDO boosts efficiency

Edited by the Electronicstalk editorial team Dec 19, 2002

National Semiconductor has produced the world's first CMOS dual-input low dropout (LDO) voltage regulator.

National Semiconductor has produced the world's first CMOS dual-input low dropout (LDO) voltage regulator.

The new product offers the industry's lowest dropout and makes efficient linear conversion from low input voltages possible.

Optimised for low-voltage, high current applications in set-top boxes, servers and desktop PCs, the new high-current linear regulator consumes only 3mA of quiescent current without compromising transient response.

The LP3883 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 2.5V.

This feature combined with the device's guaranteed maximum dropout of less than 450mV, allows efficient linear conversion from a 2.5 or 1.8V rail.

With the LP3883, designers now have a linear alternative to complex, noisy switching regulators when generating output voltages down to 1.2V.

"National's LP3883 LDO is the latest in a long line of industry firsts, allowing designers to create 1.2V, 3A rails without recourse to a switching regulator", said Johan Hedman, Product Marketing Manager for National Semiconductor's Power Management Group in Europe.

"With CMOS dual input architecture, the LP3883 consumes only 3mA of quiescent current under all conditions.

Compare this to the quiescent current of bipolar alternative which increases to over 100mA as the regulator approaches dropout.

Furthermore, bipolar regulators place restrictions on the quality and quantity of filter capacitors for stable operation".

The LP3883's unique circuit approach enables delivery of custom voltages in 50 mV increments in the range of 1.25 to 1.8V within four weeks.

The LP3883 has an output voltage accuracy of +3% over line, load and temperature variations and features on/off control, overtemperature and overcurrent protection.

National Semiconductor's LP3883 LDO regulator with 1.2, 1.5 and 1.8V output voltages is available for shipment in 5-lead TO-220 and TO-263 packages, it is priced at $2.68 each in 1000 quantities.