Datasheet MAX38889 (Maxim) - 8

MAX38889 2.5V to 5.5V, 3A Reversible Buck/Boost Regulator for Backup Applications

System Feedback Input. Connect a resistor-divider from SYS to FBS to GND to set the 11 FBS system backup operating voltage. When VFBS is >102.5% of VFBS_BU, the supercapacitor will be charged from SYS. Charge/Discharge Current Select. During charging, the average supercapacitor current 12 ISET (ICAP_CHG) is set to ICAP_CHG = 1.5A x (33kΩ/RISET). During backup, VSYS is regulated through the boost regulator with a peak inductor current of ILX_BU = 3A x (33kΩ/RISET). System Supply. Connect to the system supply and bypass with 2x47µF and 2x22µF ceramic 13, 14 SYS capacitors to PGND. In addition, place a high-frequency filter capacitor of 1µF close to the part across the SYS and PGND pins. 15, 16 PGND Power Ground. Analog Ground. Connect the exposed pad to the ground plane with excellent thermal EP GND conduction to ambient temperature to avoid overtemperature.

www.maximintegrated.com Maxim Integrated | 8 Document Outline Product Highlights Key Applications Simplified Application Diagram Pin Configuration Absolute Maximum Ratings Package Information Electrical Characteristics Typical Operating Characteristics Pin Configuration Pin Descriptions Functional Diagram Detailed Description Application Circuits Supercapacitor Voltage Configuration System Voltage Configuration Charge/Discharge Current Configuration Charging Backup Applications Information Capacitor Selection Supercapacitor Selection Inductor Selection Status Flags BKB Flag RDY Flag Enabling the Device Charger Enable Input (ENC) Backup Enable Input (ENB) PCB Layout Guidelines Ordering Information