LM3668 Datasheet | National Semiconductor

Description The LM3668 is a synchornous buck or boost DC-DC converter optimized for powering low voltage circuits from a Li-Ion battery and input voltage rails between 2.5V and 5.5V. It has the capability to support up to 1A output current over a output voltage range of 2.8V/3.3V. The LM3668 regulates the output voltage over the plete input voltage range by automatically switching between buck or boost modes depending on the input voltage. The LM3668 has 2 N-channel MOSFETS and 2 P-channel MOSFETS arranged in a topology that provides continuous operation through the buck and boost operating modes. There is a MODE pin that allows the user to choose between an intelligent automatic PFM-PWM mode operation and forced PWM operation. During PWM mode, a fixed-frequency 2.2MHz (typ.) is used. PWM mode drives load up to 1A. Hysteretic PFM mode extends the battery life through reduction of the quiescent current to 45µA (typ.) at light loads during system standby. Internal synchronous retification provides high efficiency. In shutdown mode (Enable pin pulled low) the device turns off and reduces battery consumption to 0.01µA (typ.). The LM3668 is available in a 12-pin LLP package. A high switching frequency of 2.2MHz (typ.) allows the use of tiny surface-mount ponents including a 2.2µH inductor, a 10µF input capacitor, and a 22µF output capacitor. Features - - - - - - - - - - - - - 45µA typical quiescent current 1A maximum load current for VIN = 2.8V to 5.5V 800m A maximum load current for VIN = 2.7V 600m A maximum load current for VIN = 2.5V 2.2 MHz PWM fixed switching frequency (typ.) Automatic PFM-PWM Mode or Forced PWM Mode Wide Input Voltage Range: 2.5V to 5.5V Output Voltage Range: 2.8V/3.3V Internal synchronous rectification for high efficiency Internal soft start: 600µs Maximum start-up time 0.01µA typical shutdown current Current overload and Thermal shutdown protection Frequency Sync Pin: 1.6Mhz to 2.7MHz Applications - - - - - - Handset Peripherals MP3 players...