Linear voltage regulators with low noise, high PSRR reduce jitter and simplify power design

May 15, 2013 // By Paul Buckley
Texas Instruments Incorporated has introduced two high-current, low-dropout (LDO) linear voltage regulators with excellent noise and power supply rejection ratio (PSRR) performance in very small, easy-to-use packages.

The 250-mA LP5907 and 800-mA LP38798 LDOs feature less than 10-µVrms output noise over the 10-Hz to 100-kHz bandwidth, eliminating the need for expensive and bulky filtering in a wide range of high-performance applications.

Designed to meet the requirements of RF and analogue circuits in applications such as mobile handsets, tablets and WiFi devices, the LP5907 linear regulator provides ultra-low noise, high PSRR, low quiescent current and low line or load transient response figures. The LP5907 offers advanced noise performance without a bypass capacitor, and includes the ability for remote output capacitor placement. The device is designed to work with 1-µF input and output ceramic capacitors, and when used in conjunction with the  WEBENCH online design tool, the LP5907 speeds and simplifies the design process.  

The LP5907 generates an output noise of less than 10-µVrms to provide a clean supply for noise-sensitive applications.  A PSRR of 75 dB at 1 kHz keeps a noisy supply from reaching target application.  The output voltage range is between 1.2 V and 4.5 V in 25 mV steps enables a variety of designs.  The 0.65-mm by 0.65-mm by 0.40-mm micro SMD package allows placement close to target application.

The LP38798 is a high-performance linear regulator capable of supplying 800-mA of output current. Designed to meet the requirements of sensitive RF and analogue circuitry in applications such as basestations, the LP38798 features a linear topology on an advanced CMOS process to deliver ultra-low output noise and high PSRR at switching power supply frequencies. The LP38798 is stable with both ceramic and tantalum output capacitors and requires a minimum output capacitance of 1-µF for stability.

The LP38798 delivers an output noise of 5 µVrms.  The device’s PSRR of 90 dB at 10 kHz keeps a noisy supply from reaching target application.  The LP38798 has a wide operating input voltage range of 3 V to 20 V.  The device’s 4.0-mm by 4.0-mm by 0.8-mm WSON package