PWM controller in SOIC8 package tackles AC-DC power supply shortages
Rohm has developed external FET-type controller with pulse width modulation (PWM) current control mode to address supply chain shortages in industrial AC-DC power supply designs.
Variants of the Rohm PWM controller support low voltage power transistors from Si MOSFETs and IGBTs to SiC MOSFETs, with built-in high accuracy undervoltage prevention malfunction in a standard SOP-J8 package, equivalent to the JEDEC SOIC8.
There are four variants with different undervoltage lock out levels to drive a wide range of power semiconductors: the BD28C55FJ-LB for low-voltage MOSFETs, BD28C54FJ-LB for medium- to high-voltage MOSFETs, BD28C57LFJ-LB for IGBTs, and BD28C57HFJ-LB for SiC MOSFETs.
Going forward, the lineup will be further expanded to include products suitable to drive high-voltage MOSFETs and GaN devices.
Although the global semiconductor shortage is beginning to ease, the supply of semiconductor components for power supplies in industrial applications continues to lag behind demand says Rohm. This is particularly true for PWM controller ICs, where the limited number of manufacturers has resulted in chronic shortages, leading to numerous requests for product development.
As a result Rohm developed the PWM controller as pin to pin compatible to standard products commonly used in power supply circuits, reducing re-design and modification efforts.
All the variants have a self-recovery-type undervoltage lockout function (UVLO) with voltage hysteresis. This significantly improves application reliability by reducing the threshold voltage error to ±5%, compared to the typical ±10% of standard products.
Depending upon the input AC voltage range of the application, a wide variety of semiconductors are used for power supply circuit. Each of these semiconductors demand different undervoltage lock out levels to prevent thermal runaway in case of supply/gate voltage drop.
The PWM controller has an input voltage range of 6.9V to 28.0V, circuit current up to 2.0mA, maximum startup current of 75µA, and a maximum duty cycle of 50%.
The PWM controller family is designated for long-term supply for continuous operation of long-life industrial equipment.
More variants to support a maximum duty cycle of 100% are also being planned.