DESCRIPTION
The LTC®3537 combines a high effi ciency, 2.2MHz step-up DC/DC converter with an independent 100mA low dropout regulator (LDO). The step-up converter starts from an input voltage as low as 0.68V and contains an internal 0.4Ω switch and a 0.6Ω synchronous rectifi er that disconnects from the output when disabled in shutdown.

FEATURES
■ High Effi ciency Step-Up DC/DC Converter and LDO
Step-Up
   ■ VIN: 0.68V to 5V, VOUT: 1.5V to 5.25V
       IOUT: 100mA at 3.3V, VIN >0.8V
   ■ 2.2MHz Fixed Frequency Operation
   ■ Synchronous Rectifi er with Output Disconnect
   ■ Burst Mode Operation (Pin Selectable)
Linear LDO Regulator
   ■ VIN: 1.8V to 5.5V, VOUT: 0.6V to 5V
       IOUT: 100mA
   ■ 100mV Dropout Voltage at 50mA
   ■ 24dB Ripple Rejection at fSW
Combined
   ■ Power Good Indicators
   ■ Low-Battery Comparator
   ■ 30μA IQ
   ■ Low Profi le 3mm × 3mm × 0.75mm Package

APPLICATIONS
■ Wireless Microphones
■ Portable Medical instruments
■ Noise Cancelling/Portable Headsets
■ RF and Audio Power