LTC1682 Datasheet

• Low Output Noise: 60µV_RMS (100kHz 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 50mA
• 550kHz Switching Frequency
• Low Operating Current: 150µA
• Low Shutdown Current: 1µA
• Internal Thermal Shutdown and Current Limiting
• Available in 8-Pin MSOP and SO Packages

• VCO Power Supplies in Cellular Phones
• 2-Way Pagers
• Wireless PCMCIA Cards
• Portable Medical Instruments
• Low Power Data Acquisition
• Remote Transmitters

The LTC1682/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 V_OUT via external resistors connected to FB. The regulator is capable of supplying up to 50mA of output current. Shutdown reduces the supply current to < 5µA, removes the load from V_IN by disabling the regulator and discharges V_OUT 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.