LDOs claim excellent transient performance

Edited by the Electronicstalk editorial team Nov 17, 2006

Low-dropout voltage regulators handle both digital and analogue loads in battery-powered systems.

Low-dropout voltage regulators (LDOs) handle both digital and analogue loads in battery-powered systems such as portable medical equipment, navigation systems, handheld scanners, digital signal processing and microprocessor core supply applications.

The LP5951, LP3996 and LP5996 LDOs each feature typically less than 50mV of transient performance.

The power supply rejection ratio (PSRR) of better than 60dB reduces the switching noise from the switching regulator to provide a clean output voltage.

Using small SOT-23, LLP and SC-70 packaging along with tiny 0402 ceramic capacitors, the LDOs provide a complete solution that measures less than 20mm square.

Available in an ultra-tiny SC-70 package, the LP5951 LDO supports an input voltage below 2V and output voltage as low as 1.3V.

It is well-suited for use in designs that require the post regulator to follow a switcher.

The LP3996 and LP5996 each pack two LDOs into a tiny 10-pin thermally enhanced LLP package that measures 3 x 3mm.

Using separate enable inputs, the dual outputs can be sequenced to ensure that the input/output (I/O) of a processor is powered before its core.

In addition, the LP3996 features a power-on-reset (POR) output that can be used to keep a digital processor in a reset state until the power supply is within regulation.

Available in both 5-pin SOT-23 and SC-70 packages, the LP5951 is a 150mA CMOS LDO voltage regulator that provides regulated output voltage and low quiescent current.

When switched to shutdown mode via a logic signal at the enable pin, the power consumption is reduced to virtually zero.

The LP5951 is designed to be stable with small 0402 sise ceramic capacitors.

The LP5951 also features internal protection against short-circuit currents and over-temperature conditions.

Performance is specified for a -40 to +125C junction temperature range.

The device is available in fixed output voltages from 1.3 to 3.3V.

The LP3996 is a dual output CMOS LDO voltage regulator.

It supports a 300mA load on one output and a 150mA load on the other output with less than 36uA of quiescent current for both channels enabled simultaneously during standby.

The LM3996 has fast transient performance and supports small 0603 sise 1uF capacitors at both input and output.

For analogue loads, the noise and PSRR performance levels can be further improved with use of an external bypass capacitor.

The LP5996 is a dual output CMOS LDO voltage regulator with the same package and features as the LP3996, but does not include POR.

Available now and priced in 1000-unit quantities, the LP3996 is US $0.54 cents and the LP5996 is US $0.49.

The LP5951 is $0.23 in an SOT-23 package and $0.25 in an SC-70 package.