BD9B331GWZ-E2

PMIC - Voltage Regulators - DC DC Switching Regulators

BD9B331GWZ-E2 is an integrated low voltage, current mode DC/DC step-down synchronous switching voltage regulator. It includes the switching power FETs, the current and power sensing circuitry, the control loop and the operating circuit, integrated in a low-pin-count form with low power consumption, making it an ideal solution for space constrained system power management. The device device operates at a fixed frequency of 300kHz, allowing for the use of small size external components with no input/output current sensing, minimizing total component count.

Application Field

BD9B331GWZ-E2 is designed for space constrained applications and suitable for any Variable Output Voltage (VOUT) applications such as Microcontrollers, FPGAs, Digital Cameras, Set-top boxes, Printers and any other logic-based system needing a step-down converter solution with high efficiency, wide input voltage ranges and reduced component count.

Working Principle

The BD9B331GWZ-E2 operates as a SMPS (Switch Mode Power Supply) type voltage regulator. Essentially, it consists of two switches--the high side power MOSFET and the low side power MOSFET--and an inductor that transitions between two different states depending upon the logic-level control voltage supplied. In State A, the high side switch is OFF and the low side switch is ON, providing a path to the output capacitor. In State B, the high side switch is ON and the low side switch is OFF, thereby providing a path back to the input voltage source. This "pumping" action creates a regulated voltage at the output of the converter.

In order to maintain the output voltage at the desired level, the BD9B331GWZ-E2 utilizes a current mode control loop. Essentially, this means that the output voltage is actively monitored and compared to the reference voltage at the Mode Pins. If the output voltage is lower than the desired value, the duty cycle of the two switches is increased, allowing more current to flow through the inductor, thereby increasing the output voltage. Conversely, if the output voltage is higher than the desired value, the duty cycle of the two switches is decreased, decreasing the current flowing through the inductor and thus, reducing the output voltage.

Furthermore, the BD9B331GWZ-E2 has built-in protection circuits to ensure safe operation of the device. The device has an adjustable maximum duty cycle to prevent over-current conditions, as well as an output voltage soft-start feature and an EMI filter. The device also has an output voltage ramp-down feature that can be used to decrease the output voltage when the device is turned off.