UC2855BN Equivalent & Substitute Parts

Part Overview

The UC2855BN is a Power Factor Correction (PFC) controller IC manufactured by Texas Instruments, designed for average current mode operation at 500kHz switching frequency. This device is classified as Last Time Buy, indicating end-of-life status with limited availability. The UC2855BN operates in the 10.5V to 20V supply voltage range and is packaged in a 20-pin DIP through-hole configuration, making it suitable for legacy and industrial applications requiring PFC functionality.

Due to its Last Time Buy status, identifying functionally compatible substitute parts is essential for design continuity and long-term product support. Substitute parts must maintain equivalent PFC control functionality while accommodating differences in operating mode, switching frequency range, and packaging technology.

Substiute Parts

UC2855BN

Texas InstrumentsIn Stock: 3118UC2855BN Datasheet

Current PartRFQ

UCC28180DR

Texas InstrumentsIn Stock: 25251UCC28180DR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the UC2855BN is determined by the following critical parameters:

Functional Mode: The UC2855BN operates in average current mode PFC control. Substitute parts must provide equivalent PFC control functionality, though the control mode (average current vs. continuous conduction) may differ based on application requirements.

Switching Frequency: The UC2855BN operates at a fixed 500kHz switching frequency. Substitute parts with programmable or variable frequency ranges that encompass or exceed this frequency are acceptable for applications where frequency adjustment is feasible.

Supply Voltage Range: The UC2855BN requires 10.5V to 20V supply voltage. Substitute parts must support equivalent or broader supply voltage ranges to ensure proper biasing and operation.

Startup Current: The UC2855BN draws 150 µA at startup. Substitute parts with lower or equivalent startup current requirements are acceptable.

Operating Temperature Range: The UC2855BN operates from -40°C to 85°C. Substitute parts with equal or extended temperature ranges are acceptable.

Packaging: The UC2855BN uses through-hole 20-DIP packaging. Substitute parts may use alternative packaging technologies (surface mount) if circuit board redesign is permissible.

Compliance: Both parts must maintain ROHS3 compliance and REACH unaffected status for regulatory continuity.

Parameter Comparison

Engineering Selection Recommendations

UCC28180DR as Substitute: The UCC28180DR is an active product from Texas Instruments suitable for applications requiring PFC control with extended temperature range (-40°C to 125°C). This device operates in continuous conduction mode with a programmable frequency range of 18kHz to 250kHz, which does not directly match the UC2855BN's fixed 500kHz average current mode operation.

Regulatory Compliance: Both the UC2855BN and UCC28180DR maintain ROHS3 compliance and REACH unaffected status, ensuring regulatory continuity in replacement scenarios.

Packaging Consideration: The UCC28180DR uses 8-SOIC surface mount packaging, requiring circuit board redesign compared to the UC2855BN's through-hole 20-DIP package. This substitution is viable only when board-level modifications are permissible.

Supply Voltage: The UCC28180DR specifies 21V supply voltage, which exceeds the UC2855BN's maximum of 20V. Circuit design review is necessary to confirm compatibility within the application's power supply architecture.

Availability: The UCC28180DR is currently in active production with 25,200 units in stock, providing superior long-term availability compared to the UC2855BN's Last Time Buy status.

Frequently Asked Questions (FAQ)

Q: Can the UCC28180DR directly replace the UC2855BN without circuit modifications?

A: Direct pin-for-pin replacement is not possible due to different package types (20-DIP vs. 8-SOIC) and pin counts (20 vs. 8). Circuit board redesign and schematic review are required.

Q: What is the primary functional difference between average current mode and continuous conduction mode?

A: Average current mode (UC2855BN) regulates the average inductor current, while continuous conduction mode (UCC28180DR) operates with continuous current flow through the inductor. These modes affect harmonic distortion, EMI characteristics, and control loop dynamics.

Q: Is the UCC28180DR's 250kHz maximum frequency compatible with UC2855BN applications designed for 500kHz operation?

A: The UCC28180DR's maximum frequency of 250kHz is below the UC2855BN's 500kHz fixed frequency. Applications requiring higher switching frequency must evaluate alternative substitutes or retain the UC2855BN through Last Time Buy procurement.

Q: Does the UCC28180DR's 21V supply voltage specification create compatibility issues?

A: The UCC28180DR's 21V specification exceeds the UC2855BN's 20V maximum. Applications with supply voltages at or near 20V require verification that the UCC28180DR's bias circuitry and internal regulators function correctly within the intended power supply range.

Q: What packaging options are available for PFC controller substitutes?

A: The UC2855BN uses through-hole 20-DIP packaging. The UCC28180DR uses surface mount 8-SOIC packaging. Surface mount substitutes require PCB redesign but offer reduced board space and improved thermal characteristics.

Q: Are there temperature range advantages to using the UCC28180DR?

A: The UCC28180DR operates from -40°C to 125°C, extending the upper temperature limit by 40°C compared to the UC2855BN's -40°C to 85°C range. This is beneficial for high-temperature industrial applications.