AS7620 650mA, Ultra low Ripple Step Down DC/DC Converter 1 General Description 2 Key Features Low quiescent current for efficient partial load operation The AS7620 is an easy-to-use, high-efficiency, high-voltage, hysteretic step-down DC-DC converter, operating in asynchronous Wide Supply Voltage Range, 3.6V to 32V mode. Its low-power architecture extends hold-up time in battery- 100% Duty Cycle extends operating range backed and critical applications where maximum up-time over a wide input supply voltage range is needed, while still providing for high Pin-programmable cycle-by-cycle current limit efficiencies of up to 90% during peak current demands. Integrated PMOS eliminates bootstrap capacitor Although the AS7620 is optimized for 24V applications found in Resistor-programmable Early Power Fail Warning Input industrial and medical systems, its ability to support 100% Duty Cycle makes the AS7620 ideal for applications demanding maximum Power-Good Flag up-time and soft power fail behavior. In combination with low idle Thermal Shutdown current of only 30A, on-demand switching reduces operating Fixed 3.3V and adjustable output (1.2V to VIN) current at low load currents. By selecting an appropriate inductor value, operating current can be Small 4x4mm 12-Lead MLPQ Enhanced Power Package lowered and switching frequencies tuned to certain load conditions. Specified from -40C to +125C junction and 85C maximum A pin-strapped current limit input minimizes inductor peak current ambient temperatures and thus inductor size and cost for any given application. The device further includes output short-circuit protection and 3 Applications thermal shutdown. In shutdown mode, only 1A (typ) of current is The AS7620 is suitable for Industrial 24VDC applications like PLCs, consumed. robotics Home Security and Building Control applications Solid- state utility meters Signage and LED column power and Sensor interfaces. Figure 1. AS7620 - Block Diagram VIN LDO Level Temp Shifter Hysteretic SHDN Controller I LX Soft-Start SENSE FB + ILIM - PG V REF + - PF AS7620 + VEPF - www.ams.com/DC-DC Step-Up/AS7620 Revision 1.18 1 - 16AS7620 Datasheet - P in A s s ig n me nt s 4 Pin Assignments Figure 2. Pin Assignments (Top View) 12 11 10 VIN 1 9 GND AS7620 GND 2 8 GND PGND LX 3 7 SHDN 6 4 5 4.1 Pin Descriptions Table 1. Pin Descriptions Pin Number Pin Name Description 1 VIN High Voltage Power Supply Input Must be connected to GND 2 GND 3 LX Power Output to Inductor 4 GND Must be connected to GND 5 FB Feedback input 6 ILIM Current Limit input 7 SHDN Shutdown input, active low 8 GND Must be connected to GND 9 GND Must be connected to GND 10 PF Early Power Fail output, open drain, active LOW 11 VEPF Comparator voltage input for early power fail warning 12 PG Power Good, open drain, active HIGH output, monitors feedback voltage Pad PGND Exposed pad. Connect to GND plane to help thermal dissipation www.ams.com/DC-DC Step-Up/AS7620 Revision 1.18 2 - 16 GND PG FB VEPF ILIM PF