LTC1682 Datasheet | Linear Technology

LTC1682/LTC1682-3.3/LTC1682-5 Doubler Charge Pumps with Low Noise Linear Regulator Features s s s s s s s s s s s s s DESCRIPTIO Low Output Noise: 60µVRMS (100k Hz BW) Adjustable or Fixed Boosted Output Adjustable Output Voltage Range: 2.5V to 5.5V Fixed Output Voltages: 3.3V, 5V Wide Input Voltage Range: 1.8V to 4.4V Uses Small Ceramic Capacitors No Inductors Required Output Current up to 50m A 550k Hz Switching Frequency Low Operating Current: 150µA Low Shutdown Current: 1µA Internal Thermal Shutdown and Current Limiting Available in 8-Pin MSOP and SO Packages U APPLICATIO S s s s s s s VCO Power Supplies in Cellular Phones 2-Way Pagers Wireless PCMCIA Cards Portable Medical Instruments Low Power Data Acquisition Remote Transmitters The LTC®1682/LTC1682-3.3/LTC1682-5 are doubler charge pumps with an internal low noise, low dropout (LDO) linear regulator. These parts are designed to provide a low noise boosted supply voltage for powering noise sensitive devices such as high frequency VCOs in wireless applications. An internal doubler charge pump converts a 1.8V to 4.4V input to a boosted output, while the internal LDO regulator converts the boosted voltage to a low noise regulated output. The adjustable version allows the user to set VOUT via external resistors connected to FB. The regulator is capable of supplying up to 50m A of output current. Shutdown reduces the supply current to < 5µA, removes the load from VIN by disabling the regulator and discharges VOUT to ground through a 100Ω switch. The LTC1682 LDO regulator is stable with only 2µF on the output. Small ceramic capacitors can be used, reducing PC board area. The LTC1682/LTC1682-3.3/LTC1682-5 are short-circuit and over temperature protected. The parts are available in 8-pin MSOP and SO packages. , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO 4.2V VCO Power Supply, VIN = 2.5V to 4.4V SHUTDOWN 8 4.7µF 7 6 0.22µF 4.7µF 5 C- GND CPO C+ VIN VOUT SHDN LTC1682...