TL3843D Equivalent & Substitute Parts

Part Overview

The TL3843D is a boost, flyback, and forward regulator controller IC manufactured by Texas Instruments, designed for positive output step-up and step-up/step-down DC-DC conversion applications. This device operates as a transistor driver with frequency control capabilities across a 7.6V to 30V supply range and switching frequencies up to 500kHz. The TL3843D is currently in Last Time Buy status, indicating end-of-life production. Equivalent and substitute parts are necessary to ensure design continuity and maintain supply chain reliability for new production runs and long-term product support.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Category	Power Management (PMIC)
Package / Case	14-SOIC (0.154", 3.90mm Width)
Output Type	Transistor Driver
Function	Step-Up, Step-Up/Step-Down
Output Configuration	Positive
Topology	Boost, Flyback, Forward
Voltage - Supply (Vcc/Vdd)	7.6V ~ 30V
Frequency - Switching	Up to 500kHz
Duty Cycle (Max)	97%
Operating Temperature	0°C ~ 70°C (TA)
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the TL3843D is determined by strict alignment of the following critical parameters:

Package / Case: 14-SOIC form factor (0.154", 3.90mm Width)
Voltage - Supply (Vcc/Vdd): 7.6V ~ 30V range
Switching Frequency: Up to 500kHz capability
Output Type: Transistor Driver
Output Configuration: Positive output
Topology: Support for Boost, Flyback, and/or Forward topologies
RoHS Compliance: ROHS3 Compliant
Duty Cycle (Max): 97% or higher

Substitute parts must maintain compatibility across all these parameters. Variations in operating temperature range, product status, or packaging format (tube vs. tape & reel) do not disqualify substitution when electrical and mechanical specifications align.

Parameter Comparison

Part Number	Manufacturer	Package	Vcc/Vdd (V)	Switching Freq (kHz)	Duty Cycle Max (%)	Output Config	Topology	Temp Range (°C)	Product Status
TL3843D	Texas Instruments	14-SOIC	7.6 ~ 30	Up to 500	97	Positive	Boost, Flyback, Forward	0 ~ 70	Last Time Buy
TL3843DR	Texas Instruments	14-SOIC	7.6 ~ 30	Up to 500	97	Positive	Boost, Flyback, Forward	0 ~ 70	Active
NCV3843BVDR2G	onsemi	14-SOIC	7.6 ~ 30	500	96	Positive, Isolation Capable	Flyback	-40 ~ 125	Active
UC3843BDG	onsemi	14-SOIC	7.6 ~ 30	Up to 500	96	Positive, Isolation Capable	Boost, Flyback	0 ~ 70	Obsolete
UC3843BDR2G	onsemi	14-SOIC	7.6 ~ 30	Up to 500	96	Positive, Isolation Capable	Boost, Flyback	0 ~ 70	Active
UC3843BVDR2G	onsemi	14-SOIC	7.6 ~ 30	Up to 500	96	Positive, Isolation Capable	Boost, Flyback	-40 ~ 105	Active

Engineering Selection Recommendations

TL3843DR is the primary equivalent substitute, manufactured by Texas Instruments with identical electrical specifications and Active product status. This part maintains full compatibility with TL3843D designs while offering improved supply availability and long-term support.

NCV3843BVDR2G, UC3843BDR2G, and UC3843BVDR2G are functionally compatible alternatives from onsemi. All three maintain the required 14-SOIC package, 7.6V to 30V supply range, and up to 500kHz switching capability. NCV3843BVDR2G and UC3843BVDR2G offer extended operating temperature ranges (-40°C to 125°C and -40°C to 105°C respectively), beneficial for industrial and automotive applications. UC3843BDR2G and UC3843BVDR2G are currently Active products with established supply chains.

UC3843BDG is functionally compatible but carries Obsolete product status, making it unsuitable for new designs requiring long-term component availability.

All substitute parts maintain ROHS3 compliance and MSL 1 rating, ensuring compatibility with standard manufacturing and storage requirements.

Frequently Asked Questions (FAQ)

Q: Can TL3843DR directly replace TL3843D in existing designs?

A: Yes. TL3843DR is manufactured by Texas Instruments with identical electrical specifications, package format, and functional topology support. The only difference is packaging format (tape & reel vs. tube) and Active product status, neither of which affects circuit-level compatibility.

Q: What is the key difference between TL3843D and onsemi UC3843 variants?

A: The primary difference is manufacturer and topology support. TL3843D supports Boost, Flyback, and Forward topologies with 97% maximum duty cycle. UC3843BDR2G and UC3843BVDR2G support Boost and Flyback topologies with 96% maximum duty cycle. Both maintain identical supply voltage range, switching frequency capability, and 14-SOIC packaging. Forward topology support in TL3843D is not present in UC3843 variants.

Q: Is NCV3843BVDR2G suitable for automotive applications?

A: NCV3843BVDR2G carries AEC-Q100 automotive qualification and operates across -40°C to 125°C, making it suitable for automotive-grade designs. However, it supports only Flyback topology, not Boost or Forward topologies supported by TL3843D.

Q: What does "Isolation Capable" mean in the output configuration?

A: Isolation Capable indicates the controller can support isolated topologies through transformer-based designs. This is an additional capability that does not restrict use in non-isolated applications. Parts without this designation are equally suitable for non-isolated boost and flyback circuits.

Q: Why is UC3843BDG marked Obsolete?

A: UC3843BDG has reached end-of-life status with Texas Instruments and onsemi. While functionally compatible, it should not be selected for new designs due to limited supply availability and lack of long-term support.

Q: Are there packaging format differences between substitute parts?

A: Yes. TL3843D is supplied in Tube packaging, while TL3843DR uses Tape & Reel (TR). NCV3843BVDR2G uses Cut Tape (CT), UC3843BDG uses Tube, UC3843BDR2G uses Tape & Reel (TR), and UC3843BVDR2G uses Cut Tape (CT) & Digi-Reel. All parts use identical 14-SOIC package geometry. Packaging format affects handling and storage but not electrical performance.

Q: Can I use a substitute part with a lower maximum duty cycle?

A: Substitutes with 96% maximum duty cycle (onsemi variants) are compatible with designs operating at or below 96% duty cycle. If your design requires the full 97% duty cycle capability of TL3843D, use TL3843DR to maintain specification margin.

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