link to page 13 link to page 13 link to page 17 MAX17577, MAX17578 4.5V to 60V, 1A High-Efficiency, Synchronous, Inverting Output DC-DC Converters Pin ConfigurationMAX17577, MAX17578 TOP VIEW IN 1 + 12 OUT EN/UVLO 2 11 LX RESET 3 MAX17577/ 10 BST 4 MAX17578 SS 9 GND VCC 5 8 SOUT EP RT/SYNC 6 7 FB TDFN-EP3mm x 3mmPin DescriptionPINNAMEFUNCTION Power Supply Input Pin. Decouple the IN pin to GND with a minimum of 2.2μF X7R ceramic 1 IN capacitor. Place the capacitor close to the IN and GND pins. Enable/Undervoltage-Lockout Input Pin. Drive EN/UVLO high to enable the converter. Connect to the midpoint of a resistor divider connected between the IN and GND pins to set the input voltage 2 EN/UVLO above which the device turns on. Connect to the IN pin for always on operation. Pull low to GND to disable the device. Active-Low Open-Drain Status Output Pin. The RESET output is driven low to GND if the output voltage drops below 92% of its set value. RESET goes high 1024 cycles after the output voltage 3 RESET rises above 95% of its set value. Connect a pullup resistor of 10kΩ from the RESET pin to an external power supply for monitoring the output voltage status. 4 SS Soft-Start Input Pin. Connect a capacitor from the SS pin to SOUT pin to set the soft-start time. 5V Internal LDO Output Pin. Bypass V 5 V CC with a 2.2μF ceramic capacitor to SOUT. LDO does not CC support the external loading on VCC. Switching Frequency Programming Input/External Clock Synchronization Input Pin. Connect a resistor from RT/SYNC to SOUT to set the internal clock frequency between 400kHz and 2.2MHz. 6 RT/SYNC Leave RT/SYNC open for the default 600kHz switching frequency. The RT/SYNC pin can also be used to synchronize the converter to an external clock. See the Switching Frequency and External Clock Synchronization section for more details. Feedback Input Pin. Connect FB to the center node of a resistor divider between the GND node 7 FB and output-voltage node. See the Adjusting Output Voltage section for details. Reference Node for Internal Control Circuitry. Connect SOUT to an output capacitor with a Kelvin 8 SOUT connection. Refer to the MAX17577 or MAX17578 evaluation kit data sheets for a layout example. System Ground Pin. Connect GND to the power ground plane. Connect all the circuit ground 9 GND connections together at a single point. Refer to the MAX17577 or MAX17578 evaluation kit data sheets for a layout example. Bootstrap Capacitor Pin. Connect a minimum of 0.1μF ceramic capacitor between the BST and LX 10 BST pins. Switching Node. Connect the LX pin to the switching side of the inductor. LX is high-impedance 11 LX when the device is shut down. www.maximintegrated.com Maxim Integrated | 10 Document Outline General Description Applications Benefits and Features Simplified Application Circuit Absolute Maximum Ratings Package Information TDFN Electrical Characteristics Electrical Characteristics (continued) Typical Operating Characteristics Typical Operating Characteristics (continued) Pin Configuration MAX17577, MAX17578 Pin Description Pin Description (continued) Functional Diagrams MAX17577/MAX17578 Block Diagram Detailed Description Switching Frequency and External Clock Synchronization Linear Regulator (VCC) Operating Input-Voltage Range Overcurrent Protection (OCP)/Hiccup Mode RESET Output Prebiased Output Thermal-Shutdown Protection Applications Information Inductor Selection Load Current Capability (IOUT(MAX)) Input Capacitor Selection Output-Capacitor Selection Soft-Start Capacitor Selection Adjusting Output Voltage Setting the Input Undervoltage-Lockout Level Inductive Output Short-Circuit Protection Power Dissipation PCB Layout Guidelines Typical Application Circuits -5V Typical Application Circuits Typical Application Circuits (continued) -12V Typical Application Circuit Ordering Information Revision History
