LM3668

The LM3668 is a synchronous buck-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 the output voltage range. The LM3668 regulates the output voltage over the complete 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 rectification 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 components including a 2.2µH inductor, a 10µF input capacitor, and a 22µF output capacitor.