LM20323MHX/NOPB Integrated Circuits (ICs)

The LM20323MHX/NOPB is a synchronous rectifying, monolithic, dc-dc step-down switching regulator. It was specifically designed to provide the high current voltage regulation required by consumer and small office/home office (SOHO) application. This switching regulator provides superior performance, flexibility and value in comparison to its predecessor parts including the LM1831 and LM15625. As well as being a low-voltage regulator with 3A current regulation capability, the LM20323MHX/NOPB also provides very good efficiency, low operating noise and a very low minimum operating temperature.

The LM20323MHX/NOPB application field includes but is not limited to applications requiring systems such as solid state lighting (SSL) solutions, gaming systems, SMPS, low voltage/high energy motor drives and various industrial automation systems. The device is ideal for providing adjustable output voltage ranging from 1.2V-5.5V for currents up to 3A.

Working Principle

The LM20323MHX/NOPB is a constant output voltage DC-DC switching regulator that functions in a nonlinear manner. The IC works by switching a feedback control loop with a comparator and an error amplifier at a given frequency. A fraction of the output voltage is fed back to the error amplifier signal. The error amplifier adjusts the REF voltage signal until it matches the FB signal.

The signal is then sent to an oscillator and comparator. The oscillator frequency is determined by the frequency set resistor. The comparator will direct the signal to either the high side MOSFET or the low side MOSFET when its signal exceeds the other. This will intermittently allow the current from the transformer to reach the load or not depeding of the state of the MOSFETS. If the current does not reach the load then the output voltage will rise and be detected by the error amplifier.

The loop will then continue and the cycle will be repeated until the output voltage is stabilized. The enable pin of the LM20323MHX/NOPB is used to turn the device on and off and the voltage across the MOSFETs is controlled by the PWM current limit (ILIM) pin.

Advantages

The LM20323MHX/NOPB has several advantages, including a wide input voltage range, wide operating temperature range, over-current protection and short circuit protection. The IC also has programmable frequency and built-in reset that enables a fast, efficient and reliable start-up. Finally, the LM20323MHX/NOPB offers a wide range of output voltages, 0.8V to 5V.

Conclusion

The LM20323MHX/NOPB switching regulator is a cost effective IC for many applications requiring a wide input voltage range and excellent current regulation capability. It works by switching a feedback control loop with a comparator and an error amplifier at a given operating frequency and is particularly suitable for applications such as low voltage/high energy motor drives, solid state lighting and various industrial automation systems. The LM20323MHX/NOPB also offers excellent efficiency, lower current consumption, over-current and short-circuit protection and a wide range of output voltages.