ROHM Semiconductor has announced a new series of external FET controller ICs with PWM current control mode optimized for AC-DC power supplies in various industrial applications. Four models are now in mass production, each for a different type of power semiconductor: BD28C55FJ-LB for low-voltage MOSFETs, BD28C54FJ-LB for medium- and high-voltage MOSFETs, BD28C57LFJ-LB for IGBTs, and BD28C57HFJ-LB for SiC MOSFETs.
A PWM controller IC is an integrated circuit used to control the voltage and current in a circuit, and it realizes the control of the power output in the circuit by adjusting the width of the pulse. The working principle of PWM controller ICs is based on narrow pulses of equal impulse but different shapes, which have the same effect when applied to a link with inertia. This means that by varying the width of the pulse (i.e., the duration of the pulse), the average voltage or current in the circuit can be controlled, enabling precise control of the load (e.g., motor, LED, etc.).
Key features of PWM controller ICs include:
High efficiency: The pulse width of the PWM signal can be adjusted as needed to effectively control the power output in the circuit, and the PWM circuit has higher efficiency and lower power consumption than traditional analog circuits.
Flexibility: By varying the duty cycle (the ratio of pulse width to period), precise control of voltage and current in the circuit can be achieved, which is suitable for a variety of applications.
Stability: The PWM signal has a fixed pulse width to provide a stable output signal, which is suitable for applications that require high-precision control.
Simplicity: PWM can be implemented by a simple digital signal processor or microcontroller and is a practical technical means.
Figure: ROHM unveils new PWM controller IC (Source: ROHM)
PWM controller ICs are used in a wide range of applications, including but not limited to:
Power management: control the voltage and current of the power output, such as mobile phone chargers, computer power supplies, etc.
Motor control: control the speed and torque of the motor, such as robots, electric vehicles, etc.
LED Lighting: Control the brightness and color change of LED lights, such as smart home systems.
Audio Processing: Controls the frequency and volume of an audio signal, such as a digital audio player.
While the global semiconductor shortage has eased, the supply of power semiconductor components for industrial applications continues to lag behind demand. PWM controller ICs, in particular, have been in short supply for a long time due to the limited number of manufacturers, driving a sharp increase in the demand for product development.
In response, ROHM has developed these PWM controller ICs to meet the stringent packaging and performance requirements of the industrial market and address ongoing power delivery challenges. Because power circuits use different semiconductors depending on the input AC voltage range, each semiconductor requires a specific undervoltage lockout (UVLO) level to prevent thermal runaway when the supply or gate voltage drops. In response to this need, ROHM offers four variants with different UVLO levels.
The new products have an input voltage range of 6.9V to 28.0V, a circuit current of up to 2.0mA, a maximum start-up current of 75μA, and a maximum duty cycle of 50%. Housed in a standard SOP-J8 package (JEDEC SOIC8 equivalent), these products are pin-pin compatible with common standard products found in power circuits, reducing the need for redesign and modification. All models are equipped with a resettable UVLO feature with voltage hysteresis. ROHM's ICs reduce the threshold voltage error to ±5% compared to the typical ±10% error of standard products, significantly improving the reliability of the application.
These ICs are designed for long-term supply, ensuring continuous operation of long-life industrial equipment. Going forward, ROHM plans to expand its product line with models suitable for driving high-voltage MOSFETs and GaN devices, as well as a variant that supports a maximum duty cycle of 100%.
