LM25118Q1MHX/NOPB

PMIC (power management integrated circuits) are widely used in electronic products. It combines various power management components into one integrated circuit, solving the complexity of power management. The LM25118Q1MHX/NOPB is a kind of DC DC switching controller that is widely applied in power management. This application report introduces its application field and working principle.

Application Field

The LM25118Q1MHX/NOPB is a wide-input synchronous switching controller integrated with a low-side MOSFET driver, designed to operate either with a minimum DC-DC voltage of 1.2V or higher, making it an ideal choice for automotive, industrial, computer and communication applications. It is capable of operating from input voltages from 7V to 72V and provides the necessary control and drive for buck, boost, buck-boost, and flyback-mode power supplies.

The device employs a proprietary advanced current-mode control architecture.It has programmable operating frequencies up to 275 kHz, allowing efficient small-capacitance, low-cost design. Advanced features including temperature fold-back, soft-start, hiccup mode and adjustable oscillator frequency allow engineering-friendly designs.

Its robust transient response time (300 ns) and superior duty cycle accuracy (±1.5%) ensure supplies meet fluctuating output current requirements. It is AEC-Q100 qualified with PPAP package for automotive grade for use in in-vehicle adapter applications.

Working Principle

The starting procedure for the LM25118Q1MHX/NOPB begins with the input-voltage sense, where the non-inverting input of the voltage error amplifier monitors the input voltage and sends the signal to the controller.The controller here then tries to maintain the connect-and-restore type sampler comparator voltage by utilizing the error amplifier, whose output signal is 1.25V.This voltage then is compared with the signal of a precision voltage reference, usually set to 0.8V, which further acts as a feedback signal to the controller.

After this, the controller modulates the MOSFET switch in order to maintain the desired output voltage. The current-sense amplifier senses the current of the output by measuring the voltage drop caused by the current. If a current limit condition is detected, the controller shuts off the MOSFET switch and forces the output voltage to a satisfactory level for starting is restarting at a later point.

In order to control the current-mode loop, the IC provides a wide range of features including soft-start, hiccup mode and adjustable oscillator frequency.The soft-start time is adjusted based on the value of the capacitor between the Soft-start pin and the ground.

The LM25118Q1MHX/NOPB is a reliable, cost-effective device for DC-DC buck, boost, buck-boost, and flyback-mode power supplies. It is AEC-Q100 qualified with PPAP packaging for automotive-grade applications, allowing designers to quickly design wide-range DC-DC applications with superior transient response times and superior duty cycle accuracy.