Doubler Charge Pump with Low Noise Linear Regulator in SOT-23

The LTC1928-5 is a doubler charge pump with an internal low noise, low dropout (LDO) linear regulator. The part is designed to provide a low noise boosted supply voltage for powering noise sensitive devices such as high frequency VCOs in wireless applications

An internal charge pump converts a 2.7V to 4.4V input to a boosted output, while the internal LDO regulator converts the boosted voltage to a low noise regulated output. The regulator is capable of supplying up to 30mA of output current. Shutdown reduces the supply current to <8µA, removes the load from VIN by disabling the regulator and discharges VOUT to ground through a 200Ω switch.

The LTC1928-5 LDO regulator is stable with only 2µF on the output. Small ceramic capacitors can be used, reducing PC board area.

The LTC1928-5 is short-circuit and overtemperature protected. The part is available in a 6-pin low profile (1mm) ThinSOT package.

Applications

* VCO Power Supplies for Cellular Phones

* 2-Way Pagers

* Wireless PCMCIA Cards

* Portable Medical Instruments

* Low Power Data Acquisition

* Remote Transmitters

* White LED Driver

* GaAs Switches

* Low Output Noise: 90µVRMS (100kHz BW)

* Low Profile (1mm) ThinSOT™ Package

* Fixed Output Voltage: 5V

* Input Voltage Range: 2.7V to 4.4V

* Uses Small Ceramic Capacitors

* No Inductors Required

* Output Current Up to 30mA

* 550kHz Switching Frequency

* Low Operating Current: 190µA

* Low Shutdown Current: 4µA

* Internal Thermal Shutdown and Current Limiting