Step-down DC-DC Converter Module
Contents
Introduction
The DC-DC module is used to reduce the input voltage and output stable 5 volts voltage. Here the LM2596 switching voltage regulator is used to regulate the voltage.
The corresponding schematic diagram is as shown in following:
Introduction of LM2596
The LM2596 regulator is monolithic integrated circuit ideally suited for easy and convenient design of a step−down switching regulator (buck converter). It is capable of driving a 3.0 A load with excellent line and load regulation. It is internally compensated to minimize the number of external components to simplify the power supply design.
Since LM2596 converter is a switch−mode power supply, its efficiency is significantly higher in comparison with popular three−terminal linear regulators, especially with higher input voltages. The LM2596 operates at a switching frequency of 150 kHz thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. Available in a standard 5−lead TO−220 package with several different lead bend options, and D2PAK surface mount package.
The other features include a guaranteed 4% tolerance on output voltage within specified input voltages and output load conditions, and 15% on the oscillator frequency. External shutdown is included, featuring 80 A (typical) standby current. Self-protection features include switch cycle−by−cycle current limit for the output switch, as well as thermal shutdown for complete protection under fault conditions.
Pin diagram and Function
Its pin functions are as shown in following:
| Pin | Name | Description |
|---|---|---|
| 1 | VIN | This is the positive input supply for the IC switching regulator. A suitable input by pass capacitor must be present at this pin to minimize voltage transients and to supply the switching currents needed by the regulator. |
| 2 | GND | Circuit ground |
| 3 | OUTPUT | Internal switch. The voltage at this pin switches between (+V IN − V SAT) and approximately −0.5V, with a duty cycle of approximately V OUT /V IN. To minimize coupling to sensitive circuitry, the PC board copper area connected to this pin should be kept to a minimum |
| 4 | Feedback | Senses the regulated output voltage to complete the feedback loop |
| 5 | ON/OFF | Allows the switching regulator circuit to be shut down using logic level signals thus dropping the total input supply current to approximately 80 µA. Pulling this pin below a threshold voltage of approximately 1.3V turns the regulator on, and pulling this pin above 1.3V (up to a maximum of 25V) shuts the regulator down. If this shutdown feature is not needed, the ON /OFF pin can be wired to the ground pin or it can be left open; in either case the regulator will be in the ON condition
FeaturesFixed output voltage: 5V ApplicationsSimple high-efficiency step-down (buck) regulator |
