L4981BD

Overview

The L4981BD is a Power Factor Correction (PFC) controller from STMicroelectronics, part of the L4981A series. It operates in fixed frequency average current mode with a switching frequency of 115 kHz. The device supports universal input mains voltages between 85V and 265V without requiring line switches. It utilizes BCD 60II technology to achieve high efficiency and sinusoidal line current consumption. Key electrical parameters include a maximum supply voltage of 19V, a minimum operating voltage of 12V, and a typical start-up current of 0.3mA. It features integrated overvoltage and overcurrent protection, soft start, and under-voltage lockout.

Feature Summary

• Fixed frequency average current mode PWM control for optimized input filter size
• High current bipolar and DMOS totem pole output for power MOSFET gate driving
• Integrated overvoltage and overcurrent protection with programmable thresholds
• Low start-up current and precise external voltage reference availability

Applications

• Universal input AC-DC power supplies
• Server and telecom power systems
• High efficiency-mode power pre-regulators
• Systems requiring sinusoidal line current consumption

Procurement Notes

Verify the specific suffix 'D' indicates the SOIC-20 surface mount package variant. Confirm the 'TR' designation if tape and reel packaging is required versus tube. Ensure compatibility with the 115 kHz fixed frequency operation mode distinct from the line-modulated L4981B variant. Check RoHS compliance status as older revisions may differ.

Selection Notes

Select this component when fixed frequency operation is preferred to minimize input filter size compared to line-modulated alternatives. It is suitable for designs requiring average current mode control without slope compensation. Consider the SOIC-20 package constraints and thermal performance within the -40°C to 125°C operating range. Verify that the 19V maximum supply voltage aligns with the system's VCC requirements.

Part Context

The L4981BD belongs to the L4981 family of PFC controllers designed for high power factor applications up to 0.99. The 'L4981A' designation typically refers to the fixed frequency version, while 'L4981B' denotes line-modulated frequency. The 'D' suffix specifies the SOIC-20 surface-mount package. This family replaces older DIP versions and offers enhanced integration for efficient power supply design.

Replacement Considerations

The L4981A is listed as obsolete with the L4981BD identified as a similar replacement. Verify pinout and functional compatibility before substitution. The L4981AD013TR is a direct equivalent in the same package and operational mode.