LM2594DADJR2G ON Semiconductor

LM2594 0.5 A, Step-Down Switching Regulator The LM2594 regulator is monolithic integrated circuit ideally suited for easy and convenient design of a stepdown switching regulator (buck converter). It is capable of driving a 0.5 A load with excellent line and load regulation. This device is available in adjustable output LM2594 12 V Feedback Unregulated +V DC Input IN 4 R1 = 1 k C FF R2 = 3k LM2594 L1 7 100 H Output 8 V = 5 V I = 0.5 A OUT load C = 68 F C OUT IN 56 ON/OFF GND 220 F D1 1N5817 Figure 1. Typical Application 0.5 Figure 2. Representative Block Diagram PIN FUNCTION DESCRIPTION Pin No. Symbol Description (Refer to Figure 1) 1 3 NC Not Connected 4 FB This pin is the direct input of the error amplifier and the resistor network R2, R1 is connected externally to allow programming of the output voltage. 5 ON/OFF Allows the switching regulator circuit to be shut down using logic levels, thus dropping the total input supply current to approximately 50 A. The threshold voltage is typical. 1.6 V. Applying a voltage above this value (up to V ) shuts the regulator off. If the voltage applied to this pin is lower than 1.6 V or if this pin is left open, IN the regulator will be in the on condition. 6 GND Circuit ground pin. See the information about the printed circuit board layout. 7 +V Positive input supply for LM2594 step down switching regulator. In order to minimize voltage transients and IN to supply the switching currents needed by the regulator, a suitable input bypass capacitor must be present (C in Figure 1) IN 8 OUTPUT Emitter of the internal switch. The saturation voltage Vsat of the output switch is typically 1 V. It should be kept in mind that PCB area connected to this pin should be kept to a minimum in order to minimize coupling to sensitive circuitry