The CC552733BB-SL130G, a component of the “Power-On SoC” family of IP-cores from Cosmic Circuits, is a uck-boost DC-DC switching converter that converts input power-supply voltage of 2.7-5.5V to a output voltage of 3.3V. The switch-over between the buck and boost operation is handled internally and is transparent to the system. The module requires an reference input of 1.22V. The efficiency of the DCDC converter is optimized for light-load steady- state situations typical of handheld battery powered applications. The efficiency in buck mode at medium load condition of 200mA is >90%, while the efficiency at high load current of 650mA is 80%. Inbuilt soft-start implementation prevents high-inrush current on power-on. A current limit of 1A provides protection from fault conditions. A power-down feature allows for a shut-off state with very low leakage current.
- Buck-boost DC-DC conversion from Li-Ion battery
- Input power-supply from 2.7V to 5.5V
- Connects directly to Li-Ion battery
- Buck-boost operation for longer battery life
- Smooth and automatic transition between buck and boost modes
- Maximum output current of 650mA
- PFM mode for High efficiency at low output current in buck mode of operation
- High efficiency of 90% at high output current of 200mA in buck mode
- High switching frequency of 1MHz
- In –built Soft-start, current limit
- Silterra 0.13um 6LM, 3.3V IO MOS process
- A typical buck regulator that converts from a Li-Ion battery supply to a 3.3V output supply suffers from the draw-back of not utilizing the battery after the battery voltage has gone down below 3.5V. In order to extract all the available battery life from the battery, it is important to use the battery for voltages less than 3.5V also. This is where a buck-boost DC-DC converter is of use, where the input supply from the battery supply could have discharged down to a low 2.7V, and the system still remains functional. The design incorporates a fast and automatic transition scheme between the buck and boost modes that keeps the maximum ripple during the transition to 200mV. The buck-boost converter uses a unique two-inductor topology to maximize efficiency for a wide range of output current loads. At low-currents, the buck converter switches into a PFM mode in order to achieve high efficiency. Inbuilt sense and control is provided to automatically switch from buck to boost operation. The buck-boost converter makes use of the process technology capabilities to operate at a high 1MHz switching frequency, thereby limiting the values of the inductors to a low 4.7uH and 0.4uH for the buck and the boost respectively. By operating directly from the Li-Ion battery, need for any additional on-board PWM converter is eliminated, resulting in low system BOM costs. Additionally, a current limit feature and a soft-start are provided.