Uninterruptable power supplies need a reliable switch over mechanism to ensure the output voltage remains continuous when the main power source goes down. The new LTC3118 regulator chip from Linear Technology is a synchronous buck-boost DC/DC converter which takes care of the switch over automatically and accepts two input power sources in the range of 2.2 V to 18 V.
The wide input voltage range allows either input to be either above, below or equal to the programmable output voltage. The current-mode converter uses a fixed 1.2 MHz switching frequency and can supply up to 2 A continuous output power.
Main features of the LTC3118 include:
- Integrated high efficiency dual input PowerPath plus Buck-Boost DC/DC converter
- Ideal diode or priority VIN select modes
- VIN1 and VIN2 range: 2.2 V to 18 V
- VOUT range: 2 V to 18 V
- VIN can be above, below or equal to VOUT
- Generates 5V at 2A for VIN > 6V
- 1.2 MHz low noise fixed frequency operation
- Current mode control
- All internal N-Channel MOSFETs
- Pin-selectable PWM or Burst Mode operation
- Accurate, independent RUN pin thresholds
- Up to 94% efficiency
- VIN and VOUT power-good indicators
- IQ of 50 μA in sleep, 2 μA in shutdown
- 4 mm × 5 mm 24-lead QFN or 28-lead TSSOP packages
In a typical application the main input power may be provided by a wall adapter unit while the backup can be either batteries or supercaps.