The STEVAL-ISA063V2 demonstration board implements a typical buck-boost DC-DC converter based on STMicroelectronics’ STBB1-APUR high efficiency single inductor dual mode buck-boost DC-DC converter. The device is fixed frequency and capable of providing output voltages ranging from 1.2 V to 5.5 V and input voltages from 2.0 V to 5.5 V.
The STBB1-APUR can operate with input voltages higher than, equal to, or lower than the output voltage, rendering the product suitable for single lithium-ion (Li-Ion), multicell alkaline or NiMH applications where the output voltage is within the battery voltage range.
The integrated low-RDSonN-channel and P-channel MOSFET switches contribute to its high efficiency.

Buck-boost DC-DC converter
Operating input voltage range: 2.0 V to 5.5 V
2% DC feedback voltage tolerance
Synchronous rectification
Shutdown function
1.5 MHz switching frequency
Power save mode at light load
Typical efficiency: > 94%
1 A output current capability
Shutdown current: < 1 μA