UC3845BVDR2 Equivalent & Substitute Parts

Part Overview

The UC3845BVDR2 is a Boost/Flyback Regulator Controller IC manufactured by onsemi, designed for Step-Up and Step-Up/Step-Down DC-DC conversion applications. This component operates as a Transistor Driver with Positive, Isolation Capable output configuration in a 14-SOIC surface mount package.

The UC3845BVDR2 is classified as Obsolete. Equivalent and substitute parts are necessary to maintain design continuity, ensure supply chain availability, and meet current compliance requirements such as RoHS3 compliance and active product status.

Key Parameters

Parameter	UC3845BVDR2
Manufacturer	onsemi
Package / Case	14-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Voltage - Supply (Vcc/Vdd)	7.6V ~ 30V
Frequency - Switching	Up to 500kHz
Duty Cycle (Max)	48%
Output Type	Transistor Driver
Function	Step-Up, Step-Up/Step-Down
Topology	Boost, Flyback
Operating Temperature	-40°C ~ 105°C (TA)
Product Status	Obsolete
RoHS Status	RoHS non-compliant

Substitute Part Grouping Explanation

Substitute parts for the UC3845BVDR2 are classified based on the following substitution criteria:

Direct Equivalents (Same Base Part Number, Different Packaging or Compliance):

UC3845BVDR2G (onsemi): Identical electrical specifications, Tape & Reel packaging, RoHS3 Compliant, Active status
UC3845AD (Texas Instruments): Same base UC3845 platform, 14-SOIC package, RoHS3 Compliant, Active status
UC3845ADTR (Texas Instruments): Same base UC3845 platform, Tape & Reel packaging, RoHS3 Compliant, Active status
UC3845D (Fairchild Semiconductor): Same base UC3845 platform, 14-SOIC package, RoHS3 Compliant, Obsolete status
UC3845DTR (Texas Instruments): Same base UC3845 platform, Tape & Reel packaging, RoHS3 Compliant, Active status

Similar Alternatives (Compatible Topology and Function, Different Base Part Number):

TL2845BD (Texas Instruments): Boost/Flyback/Forward topology, 7.6V ~ 30V supply, Up to 500kHz switching, 14-SOIC package, RoHS3 Compliant, Last Time Buy status
TL2845BDR (Texas Instruments): Boost/Flyback/Forward topology, 7.6V ~ 30V supply, Up to 500kHz switching, Tape & Reel packaging, RoHS3 Compliant, Active status
TL3845BD (Texas Instruments): Boost/Flyback/Forward Converter topology, 7.6V ~ 30V supply, 100kHz switching, 14-SOIC package, RoHS3 Compliant, Last Time Buy status
TL3845BDR (Texas Instruments): Boost/Flyback/Forward Converter topology, 7.6V ~ 30V supply, 100kHz switching, Tape & Reel packaging, RoHS3 Compliant, Last Time Buy status
TL3845D (Texas Instruments): Boost/Flyback/Forward Converter topology, 7.6V ~ 30V supply, 100kHz switching, 14-SOIC package, RoHS3 Compliant, Active status, AEC-Q100 Automotive Qualified

Parameter Comparison

Part Number	Manufacturer	Package	Vcc/Vdd (V)	Switching Freq	Duty Cycle Max	Temp Range (°C)	Status	RoHS
UC3845BVDR2	onsemi	14-SOIC	7.6 ~ 30	Up to 500kHz	48%	-40 ~ 105	Obsolete	Non-compliant
UC3845BVDR2G	onsemi	14-SOIC (TR)	7.6 ~ 30	Up to 500kHz	48%	-40 ~ 105	Active	RoHS3
UC3845AD	Texas Instruments	14-SOIC	7.6 ~ 30	Up to 500kHz	48%	0 ~ 70	Active	RoHS3
UC3845ADTR	Texas Instruments	14-SOIC (TR)	7.6 ~ 30	Up to 500kHz	48%	0 ~ 70	Active	RoHS3
UC3845D	Fairchild Semiconductor	14-SOIC	7.6 ~ 30	Up to 500kHz	48%	0 ~ 70	Obsolete	RoHS3
UC3845DTR	Texas Instruments	14-SOIC (TR)	12 ~ 28	Up to 500kHz	48%	0 ~ 70	Active	RoHS3
TL2845BD	Texas Instruments	14-SOIC	7.6 ~ 30	Up to 500kHz	48%	-40 ~ 85	Last Time Buy	RoHS3
TL2845BDR	Texas Instruments	14-SOIC (TR)	7.6 ~ 30	Up to 500kHz	48%	-40 ~ 85	Active	RoHS3
TL3845BD	Texas Instruments	14-SOIC	7.6 ~ 30	100kHz	48%	0 ~ 70	Last Time Buy	RoHS3
TL3845BDR	Texas Instruments	14-SOIC (TR)	7.6 ~ 30	100kHz	48%	0 ~ 70	Last Time Buy	RoHS3
TL3845D	Texas Instruments	14-SOIC	7.6 ~ 30	100kHz	48%	0 ~ 70	Active	RoHS3

Engineering Selection Recommendations

Primary Recommendation: UC3845BVDR2G

UC3845BVDR2G is the direct equivalent of UC3845BVDR2 with identical electrical specifications and 14-SOIC package footprint. This part is manufactured by onsemi with Active product status and RoHS3 compliance, addressing the obsolescence and compliance limitations of the original UC3845BVDR2.

Secondary Recommendations: UC3845ADTR or UC3845AD

Texas Instruments UC3845ADTR (Tape & Reel) and UC3845AD (Tube) maintain the same base UC3845 platform with identical supply voltage range (7.6V ~ 30V), switching frequency (Up to 500kHz), and duty cycle specifications. Both are RoHS3 compliant and Active status. Operating temperature range is 0°C ~ 70°C, which is narrower than the original -40°C ~ 105°C specification.

Alternative Consideration: TL2845BDR

TL2845BDR from Texas Instruments provides compatible Boost/Flyback/Forward topology with identical supply voltage (7.6V ~ 30V) and switching frequency (Up to 500kHz). This part is Active status and RoHS3 compliant. Operating temperature range is -40°C ~ 85°C. The extended temperature range at the lower end matches the original specification better than UC3845 alternatives.

Extended Temperature Applications: TL3845D

For applications requiring the full -40°C ~ 105°C operating range, TL3845D offers Boost/Flyback/Forward Converter topology with 7.6V ~ 30V supply voltage and 48% maximum duty cycle. This part includes AEC-Q100 Automotive qualification and is Active status with RoHS3 compliance. Switching frequency is fixed at 100kHz, which differs from the original 500kHz maximum.

Frequently Asked Questions (FAQ)

Q: Can UC3845BVDR2G be used as a direct replacement for UC3845BVDR2?

A: Yes. UC3845BVDR2G is electrically and mechanically identical to UC3845BVDR2, with the same 14-SOIC package, supply voltage range (7.6V ~ 30V), switching frequency (Up to 500kHz), and duty cycle (48%). The primary differences are Active product status and RoHS3 compliance.

Q: What is the difference between UC3845ADTR and UC3845AD?

A: Both parts are identical in electrical specifications and package type (14-SOIC). The difference is packaging format: UC3845ADTR is supplied in Tape & Reel (TR) for automated assembly, while UC3845AD is supplied in Tube for manual handling. Select based on assembly process requirements.

Q: Why do TL3845 parts have 100kHz switching frequency instead of 500kHz?

A: TL3845 is a different base part number with fixed 100kHz switching frequency, compared to UC3845 which supports up to 500kHz. This is a design difference between the two controller families. Applications requiring higher switching frequencies should use UC3845-based alternatives.

Q: Is TL2845BDR suitable for applications requiring -40°C operation?

A: Yes. TL2845BDR operates from -40°C ~ 85°C, which covers the lower temperature extreme of the original UC3845BVDR2 (-40°C ~ 105°C). However, the upper temperature limit is 85°C instead of 105°C. Verify application requirements before selection.

Q: What does "Last Time Buy" status mean for TL3845BD and TL3845BDR?

A: Last Time Buy indicates these parts are being discontinued. Existing inventory is available for purchase, but no new production is planned. For long-term supply chain stability, select Active status parts such as TL3845D or UC3845BVDR2G.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts are RoHS3 compliant. The original UC3845BVDR2 is RoHS non-compliant. RoHS3 compliance is required for new designs and many procurement specifications.

Q: Can UC3845DTR be used if the supply voltage range is 12V ~ 28V?

A: UC3845DTR has a narrower supply voltage range (12V ~ 28V) compared to UC3845BVDR2 (7.6V ~ 30V). This part is suitable only if your application operates within the 12V ~ 28V window. For full 7.6V ~ 30V range support, use UC3845BVDR2G, UC3845AD, or UC3845ADTR.

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