GBI1450SMAR

GBI1450 is a 40V, 5A step-down converter with an integrated 80mΩ high-side MOSFET. The device features a wide 4.0V to 40V input range, making it suitable for various applications powered by unregulated supplies. It employs peak current mode control and supports a wide adjustable switching frequency range of 200kHz to 2.5MHz set via an external resistor. Quiescent current in sleep mode is 100uA, and shutdown current is 1uA, making it well-suited for battery-powered systems. The device integrates multiple protection features, including cycle-by-cycle current limiting, thermal shutdown, output overvoltage protection, input undervoltage lockout, and hiccup mode under overcurrent and output hard short-circuit conditions. It is housed in an 8-pin eSOP-8L package. The device features a default 3.6V input startup voltage with 350mV hysteresis. The EN pin is a high-voltage pin with a precision threshold, allowing the input voltage lockout threshold to be adjusted via two external resistors to meet precise, higher UVLO system requirements. Leaving the EN pin floating enables the device, while connecting EN directly to VIN enables automatic startup. The device also supports monotonic startup into a pre-biased output. GBI1450 employs fixed-frequency peak current mode control. An internal clock initiates turn-on of the integrated high-side power MOSFET at the beginning of each cycle, after which the inductor current rises linearly. When the current through the high-side MOSFET reaches the threshold level set by the internal compensation voltage of the internal error amplifier, the high-side MOSFET turns off. After the high-side MOSFET turns off, the inductor current freewheels through an external diode until the next clock cycle begins. The integrated error amplifier and internal compensation form a feedback loop to regulate the output voltage to the reference. The error amplifier compares the voltage at the FB pin against an internal reference voltage of 0.8V. An increase in load current reduces the feedback voltage, which raises the error amplifier output voltage until the average inductor current matches the increased load current. The device also integrates an internal slope compensation circuit to prevent subharmonic oscillation when the duty cycle exceeds 50%. GBI1450 operates in pulse skip mode at light load currents to improve efficiency. Decreasing load current causes the feedback voltage to rise, which pulls the compensation voltage down. When the compensation voltage drops below the low clamp threshold, PSM is triggered. During skip cycles, discharge of the output capacitor causes the output voltage to drop, attenuating the FB voltage. Once the FB voltage falls below the reference voltage and the compensation voltage rises above the low clamp threshold, the integrated high-side MOSFET turns on at the next clock pulse. After several switching cycles with a typical peak inductor current of 0.35A, the internal compensation voltage decreases and is clamped again; if the output remains lightly loaded, the pulse skip mode repeats. This PSM reduces switching power losses and gate drive charge losses by skipping cycles, contributing to higher efficiency.

Applications

• 12V/24V industrial power systems
• Industrial automation and motor control
• Automotive accessories

Key features

• Wide input range: 4.0V–40V
• Up to 5A continuous output current
• 0.8V ±1.25% feedback reference voltage
• Integrated 80mΩ high-side power MOSFET
• Adjustable frequency: 200kHz to 2.5MHz
• Pulse skip mode at light load
• 100uA quiescent current in sleep mode
• Programmable soft-start time
• Integrated loop compensation
• eSOP-8L package