REG103GA-3 Equivalent & Substitute Parts

Part Overview

The REG103GA-3 is a linear voltage regulator IC from Texas Instruments designed for positive fixed 3V output at 500mA in a SOT-223-6 surface mount package. This part is classified as obsolete, making identification of suitable equivalent and substitute components essential for ongoing design support and production continuity. The REG103GA-3 serves applications requiring stable 3V regulation with moderate current capacity and integrated protection features.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Part Number	REG103GA-3
Product Status	Obsolete
Output Configuration	Positive
Output Type	Fixed
Voltage - Output (Fixed)	3V
Current - Output	500mA
Voltage - Input (Max)	15V
Voltage Dropout (Max)	0.28V @ 500mA
Package / Case	SOT-223-6
Operating Temperature	-40°C ~ 85°C
Protection Features	Over Current, Over Temperature
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the REG103GA-3 is determined by the following critical parameters:

Output Voltage: Fixed 3V output is the primary functional requirement
Output Current: Minimum 500mA capacity required
Input Voltage Range: Maximum input of 15V or greater
Package Compatibility: SOT-223-6 surface mount package
Dropout Voltage: Lower dropout preferred for efficiency
Protection Features: Over current and over temperature protection
Compliance: ROHS3 compliance maintained

Two substitute parts are identified based on these criteria:

MCP1825T-3002E/DC (Microchip Technology) - Direct functional equivalent with fixed 3V output, 500mA capacity, and active product status. Offers improved specifications including lower quiescent current and extended operating temperature range.

REG104GA-A (Texas Instruments) - Alternative from the same manufacturer family with adjustable output capability, higher current capacity (1A), and last-time-buy status. Requires external resistor network for 3V fixed output configuration.

Parameter Comparison

Parameter	REG103GA-3	MCP1825T-3002E/DC	REG104GA-A
Manufacturer	Texas Instruments	Microchip Technology	Texas Instruments
Product Status	Obsolete	Active	Last Time Buy
Output Type	Fixed	Fixed	Adjustable
Voltage - Output	3V	3V	1.295V - 5.5V
Current - Output	500mA	500mA	1A
Voltage - Input (Max)	15V	6V	15V
Voltage Dropout (Max)	0.28V @ 500mA	0.35V @ 500mA	0.48V @ 1A
Current - Quiescent (Iq)	0.7 mA	220 µA	0.7 mA
Package / Case	SOT-223-6	SOT-223-6	SOT-223-6
Operating Temperature	-40°C ~ 85°C	-40°C ~ 125°C	-40°C ~ 85°C
Protection Features	Over Current, Over Temperature	Over Temperature, Short Circuit, UVLO	Over Current, Over Temperature
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

MCP1825T-3002E/DC is the primary recommended substitute. This part maintains active product status, ensuring long-term availability and supply chain stability. It provides identical fixed 3V output and 500mA current capacity with direct pin compatibility in the SOT-223-6 package. The lower quiescent current (220 µA vs. 0.7 mA) offers improved efficiency in battery-powered applications. Extended operating temperature range (-40°C to 125°C) provides broader environmental coverage. The input voltage maximum of 6V is lower than the original 15V specification; applications requiring higher input voltages must verify compatibility with actual circuit conditions.

REG104GA-A serves as an alternative for designs requiring higher current capacity (1A) or adjustable output voltage. This part maintains Texas Instruments manufacturer continuity but carries last-time-buy status, indicating limited future availability. The adjustable output requires external resistor configuration to achieve 3V fixed output, adding design complexity. Input voltage compatibility remains at 15V maximum, matching the original specification.

Frequently Asked Questions (FAQ)

Q: Can MCP1825T-3002E/DC be used as a direct drop-in replacement for REG103GA-3?

A: Yes, for applications with input voltages up to 6V. Both parts provide fixed 3V output, 500mA capacity, and identical SOT-223-6 package pinout. Verify your circuit's maximum input voltage against the 6V limit of the MCP1825T-3002E/DC.

Q: What is the difference between fixed and adjustable output types?

A: Fixed output regulators (REG103GA-3, MCP1825T-3002E/DC) provide a preset voltage determined by internal resistor networks. Adjustable output regulators (REG104GA-A) require external resistors to set the output voltage, offering design flexibility but requiring additional components and PCB space.

Q: Why does MCP1825T-3002E/DC have a lower input voltage maximum than REG103GA-3?

A: The MCP1825T-3002E/DC is optimized for lower voltage input applications with improved efficiency characteristics. Applications requiring 15V input capability should use REG104GA-A or verify that actual circuit input voltages remain below 6V.

Q: Are all three parts ROHS3 compliant?

A: Yes, REG103GA-3, MCP1825T-3002E/DC, and REG104GA-A are all ROHS3 compliant, meeting environmental and regulatory requirements for current manufacturing standards.

Q: What is the significance of product status (Obsolete, Active, Last Time Buy)?

A: Obsolete parts are no longer manufactured and have limited stock availability. Active parts have ongoing production and guaranteed long-term supply. Last Time Buy parts have announced end-of-life with a final purchase window. For new designs, Active status (MCP1825T-3002E/DC) is preferred for supply chain reliability.

Q: Can REG104GA-A be configured for 3V fixed output?

A: Yes, REG104GA-A is adjustable and can be configured for 3V output using external resistors. This requires additional design effort and component cost compared to fixed-output alternatives.

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