Dc/Dc Converter

Description: This circuit utilizes a Linear Technology LT1073 to function as a -24 V converter. The power supply can consist of two AA cells (3 V) or a 5 V source. The circuit is capable of delivering a current of 7 mA.

The LT1073 is a high-performance, low-noise voltage regulator that can be configured for various output voltages, including negative voltages. In this application, it is employed to convert a lower input voltage into a -24 V output, making it suitable for powering devices that require a negative voltage supply.

The circuit design begins with the input power source, which can be either two AA batteries in series, providing a nominal voltage of 3 V, or a 5 V regulated power supply. The choice of the input voltage affects the efficiency and performance of the converter.

The LT1073 operates by switching the input voltage through an inductor, which stores energy and releases it to the output capacitor, creating a negative output voltage. The inductor value is critical for ensuring the proper operation of the converter. A typical value for the inductor in this configuration might range from 10 µH to 100 µH, depending on the desired switching frequency and load conditions.

Output capacitors are also essential for stabilizing the output voltage and reducing ripple. The selection of these capacitors should consider both capacitance and equivalent series resistance (ESR) to optimize performance. A combination of tantalum and ceramic capacitors is often used to achieve low ripple and good transient response.

The feedback loop of the LT1073 is configured to maintain the desired output voltage. A voltage divider network is used to sense the output voltage, feeding it back to the regulator to adjust the duty cycle of the switching operation, thereby stabilizing the output at -24 V.

The circuit's output current capability is rated at 7 mA, which is suitable for low-power applications. However, careful consideration of thermal management is necessary, especially when operating at maximum load conditions. Adequate heat sinking or thermal dissipation methods should be implemented to ensure the LT1073 operates within its safe temperature range.

In summary, this circuit effectively utilizes the LT1073 to create a -24 V output from a low-voltage input, providing a reliable power source for applications requiring negative voltage while ensuring stability and efficiency through careful component selection and circuit design. This circuit uses a Linear Technology LT1073 in a -24-V converter. The supply can be two AA cells (3 V) or 5 V. The circuit can deliver 7 mA.