REG104FA-AKTTT Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The REG104FA-AKTTT is a linear voltage regulator IC from Texas Instruments designed for positive adjustable output applications. This Surface Mount device delivers 1A output current in a TO-263 (DDPAK-5) package and operates across an input voltage range up to 15V with adjustable output from 1.295V to 5.5V. The part is classified as Obsolete, making identification of equivalent and substitute components essential for ongoing design support and production continuity.

Substiute Parts

REG104FA-AKTTT

Texas InstrumentsIn Stock: 1209REG104FA-AKTTT Datasheet

Current PartRFQ

REG103FA-2.7

Burr BrownIn Stock: 16708REG103FA-2.7 Datasheet

MFR RecommendedRFQ

REG104FA-A/500

Texas InstrumentsIn Stock: 2035REG104FA-A/500 Datasheet

Parametric EquivalentRFQ

REG104FA-A/500G3

Texas InstrumentsIn Stock: 721REG104FA-A/500G3 Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the REG104FA-AKTTT is determined by the following critical parameters: output configuration (Positive), output type (Adjustable), maximum output current (1A), input voltage range (15V maximum), adjustable output voltage range (1.295V to 5.5V), package type (TO-263 DDPAK-5), and control features (Enable function with Over Current and Over Temperature protection).

The substitute parts identified fall into two categories:

Parametric Equivalents (Same Electrical Characteristics): Parts that maintain identical or functionally equivalent electrical specifications, allowing direct substitution in most applications.

Functional Alternatives (Different Output Current or Voltage Configuration): Parts that share the same package and core functionality but with different electrical ratings, requiring application-level verification.

Parameter Comparison

Engineering Selection Recommendations

REG104FA-A/500G3 is the primary recommended substitute. This part maintains identical electrical specifications to the REG104FA-AKTTT, including adjustable output voltage range (1.295V to 5.5V), 1A output current, and all control and protection features. The part carries Active product status, ensuring long-term availability and supply chain stability. RoHS3 compliance is maintained, meeting current environmental and regulatory requirements.

REG104FA-A/500 serves as a secondary equivalent option. This part is electrically identical to the main part and REG104FA-A/500G3, with the exception of packaging format (Tape & Reel versus standard packaging). Product status is Last Time Buy, indicating limited future availability. This part remains suitable for applications where existing inventory or near-term procurement is feasible.

REG103FA-2.7 is a functional alternative only for applications requiring a fixed 2.7V output. This Burr Brown part shares the same TO-263 package and core regulator architecture but differs fundamentally in output type (Fixed versus Adjustable) and output current rating (500mA versus 1A). RoHS non-compliance status makes this option unsuitable for new designs or applications with environmental regulatory requirements. Selection of this part requires explicit verification that the fixed 2.7V output and reduced current capacity meet application requirements.

Frequently Asked Questions (FAQ)

Q: Can REG104FA-A/500G3 be used as a direct replacement for REG104FA-AKTTT?

A: Yes. REG104FA-A/500G3 is a direct parametric equivalent with identical electrical specifications, including adjustable output voltage range (1.295V to 5.5V), 1A output current, dropout voltage, quiescent current, and PSRR performance. Both parts use the same TO-263 DDPAK-5 package and support identical control and protection features. The primary advantage of REG104FA-A/500G3 is its Active product status, ensuring continued availability.

Q: What is the difference between REG104FA-A/500 and REG104FA-A/500G3?

A: Both parts are electrically identical with matching specifications. The primary difference is packaging format: REG104FA-A/500 is supplied in Tape & Reel format, while REG104FA-A/500G3 uses standard packaging. REG104FA-A/500 carries Last Time Buy status, indicating limited future availability, whereas REG104FA-A/500G3 is Active. For new designs, REG104FA-A/500G3 is preferred.

Q: Can REG103FA-2.7 replace the REG104FA-AKTTT?

A: REG103FA-2.7 is not a direct replacement. This part has a fixed 2.7V output, whereas the REG104FA-AKTTT provides adjustable output from 1.295V to 5.5V. Additionally, REG103FA-2.7 is rated for 500mA output current compared to 1A for the main part. Selection of REG103FA-2.7 is limited to applications requiring exactly 2.7V output at 500mA or less. REG103FA-2.7 is also RoHS non-compliant, making it unsuitable for applications with environmental regulatory requirements.

Q: Are all substitute parts available in the same TO-263 package?

A: Yes. All substitute parts listed—REG104FA-A/500, REG104FA-A/500G3, and REG103FA-2.7—use the TO-263-6 D2PAK (5 Leads + Tab) package, ensuring mechanical and thermal compatibility with the original REG104FA-AKTTT design.

Q: What is the impact of the voltage dropout difference between REG104FA-AKTTT and REG104FA-A/500?

A: REG104FA-AKTTT specifies 0.48V dropout at 1A, while REG104FA-A/500 specifies 0.58V at 1A. This 0.1V difference is within typical design margins for most applications. Applications with tight input-to-output voltage headroom should verify that the higher dropout voltage of REG104FA-A/500 remains acceptable for their specific input voltage and output current requirements.

Q: Are there RoHS compliance considerations for substitute selection?

A: Yes. REG104FA-A/500G3 and REG104FA-A/500 are both ROHS3 compliant, matching the compliance status of the original REG104FA-AKTTT. REG103FA-2.7 is RoHS non-compliant and should not be selected for applications subject to RoHS regulations or environmental compliance requirements.