National Semiconductor Corporation introduced three low-dropout voltage regulators (LDOs) for both digital as well as analog 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 50 mV of transient performance. The power supply rejection ratio (PSRR) of better than 60 dB reduces the switching noise from the switching regulator to provide a clean output voltage. Utilizing small SOT-23, LLP and SC-70 packaging along with tiny 0402 ceramic capacitors, the LDOs provide a complete solution that measures less than 20 mm squared.
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 mm by 3 mm. 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.
Technical Features of National’s LP5951 LDO
Available in both 5-pin SOT-23 and SC-70 packages, the LP5951 is a 150 mA 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 size ceramic capacitors. The LP5951 also features internal protection against short-circuit currents and over-temperature conditions. Performance is specified for a -40 degrees C to 125 degrees C junction temperature range. The device is available in fixed output voltages from 1.3V to 3.3 V.
Technical Features of National’s LP3996 and LP5996 Dual LDOs
The LP3996 is a dual output CMOS LDO voltage regulator. It supports a 300 mA load on one output and a 150 mA load on the other output with less than 36 uA of quiescent current for both channels enabled simultaneously during standby. The LM3996 has fast transient performance and supports small 0603 size 1 uF capacitors at both input and output. For analog 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.
Availability and Pricing
Available now and priced in 1,000-unit quantities, the LP3996 is 54 cents and the LP5996 is 49 cents. The LP5951 is 23 cents in a SOT-23 package and 25 cents in a SC-70 package.
