FT531AA Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The FT531AA is a linear voltage regulator IC manufactured by Fremont Micro Devices Ltd, designed for positive fixed 1.2V output at 250mA in SOT-23-5 surface mount packaging. This part is classified as obsolete, making equivalent and substitute parts necessary for new designs and production continuity. The FT531AA operates across -40°C to 85°C with integrated over-current protection and enable control features, suitable for low-power voltage regulation applications requiring fixed 1.2V output.

Key Parameters

Parameter	FT531AA
Manufacturer	Fremont Micro Devices Ltd
Output Voltage (Fixed)	1.2V
Output Current	250mA
Input Voltage (Max)	6V
Dropout Voltage	0.4V @ 100mA (Typ)
Quiescent Current	36 µA
Package	SOT-23-5 (SC-74A)
Operating Temperature	-40°C ~ 85°C
Protection Features	Over Current
Control Features	Enable
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the FT531AA is determined by the following critical parameters: fixed 1.2V output voltage, positive output configuration, enable control feature, over-current protection, SOT-23-5 or SOT-25 package compatibility, -40°C to 85°C operating temperature range, and 6V maximum input voltage rating.

Substitute parts are grouped into two categories:

Direct Substitutes (Same Output Current - 250mA): AP2139AK-1.2TRG1 matches the FT531AA output current specification of 250mA with identical 1.2V fixed output, SOT-23-5 packaging, and active product status.

Enhanced Substitutes (Higher Output Current - 300mA): AP7331-12WG-7, AP7335-12WG-7, and RT9030A-12GB provide 300mA output current capability, exceeding the FT531AA specification. These parts maintain 1.2V fixed output, compatible SOT-25 packaging, and active product status.

Lower Current Alternative (200mA): XC6221B122MR-G provides 200mA output current, suitable for applications with reduced current requirements while maintaining 1.2V output and SOT-25 packaging.

All substitute parts maintain ROHS3 compliance, enable control features, and over-current protection as specified for the FT531AA.

Parameter Comparison

Parameter	FT531AA	AP2139AK-1.2TRG1	AP7331-12WG-7	AP7335-12WG-7	RT9030A-12GB	XC6221B122MR-G
Manufacturer	Fremont Micro Devices Ltd	Diodes Incorporated	Diodes Incorporated	Diodes Incorporated	Richtek USA Inc.	Torex Semiconductor Ltd
Output Voltage (Fixed)	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V
Output Current	250mA	250mA	300mA	300mA	300mA	200mA
Input Voltage (Max)	6V	6V	6V	6V	5.5V	6V
Quiescent Current	36 µA	1.5 µA	75 µA	80 µA	50 µA	50 µA
Package	SOT-23-5	SOT-23-5	SOT-25	SOT-25	SOT-23-5	SOT-25-5
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Protection Features	Over Current	Over Current	Over Current, Over Temperature	Over Current, Over Temperature	Over Current, Over Temperature	Over Current, Short Circuit
Control Features	Enable	Enable	Enable	Enable	Enable	Enable
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Pin and Functional Replacement: AP2139AK-1.2TRG1 is the primary substitute, offering identical 250mA output current and SOT-23-5 packaging. This part maintains active product status with ROHS3 compliance and is immediately suitable for FT531AA replacement in existing designs without layout modifications.

For Enhanced Current Capability: AP7331-12WG-7 and AP7335-12WG-7 provide 300mA output current with active product status and ROHS3 compliance. These parts require SOT-25 package accommodation but offer improved thermal performance and additional over-temperature protection. AP7335-12WG-7 is supplied in Tape & Reel packaging, while AP7331-12WG-7 is available in both Cut Tape and Digi-Reel formats.

For Alternative Package Consideration: RT9030A-12GB offers 300mA output current in SOT-23-5 packaging with active product status and ROHS3 compliance. This part features a lower maximum input voltage of 5.5V compared to the FT531AA 6V specification and should be selected only when input voltage does not exceed 5.5V.

For Reduced Current Applications: XC6221B122MR-G provides 200mA output current with active product status, ROHS3 compliance, and integrated short-circuit protection. This part is suitable for applications where 250mA output current exceeds system requirements.

All substitute parts maintain ROHS3 compliance and active product status, ensuring long-term availability and regulatory compliance for new production.

Frequently Asked Questions (FAQ)

Q: Can AP2139AK-1.2TRG1 directly replace FT531AA without PCB layout changes?

A: Yes. AP2139AK-1.2TRG1 matches the FT531AA in SOT-23-5 packaging, pin configuration, and functional specifications including 250mA output current and 1.2V fixed output. No layout modifications are required.

Q: What is the primary advantage of using AP7331-12WG-7 or AP7335-12WG-7 over AP2139AK-1.2TRG1?

A: AP7331-12WG-7 and AP7335-12WG-7 provide 300mA output current compared to 250mA, offering 20% additional current capacity. Both include over-temperature protection in addition to over-current protection. These parts require SOT-25 package accommodation.

Q: Is RT9030A-12GB suitable as a direct replacement for FT531AA?

A: RT9030A-12GB maintains SOT-23-5 packaging and 300mA output current capability. However, its maximum input voltage rating is 5.5V compared to FT531AA's 6V specification. Use this part only when input voltage remains below 5.5V.

Q: What is the difference between AP7331-12WG-7 and AP7335-12WG-7?

A: Both parts provide identical 1.2V output at 300mA with SOT-25 packaging and active product status. AP7331-12WG-7 is available in Cut Tape and Digi-Reel packaging options, while AP7335-12WG-7 is supplied in Tape & Reel format. Electrical specifications are equivalent.

Q: Can XC6221B122MR-G be used in applications requiring 250mA output current?

A: XC6221B122MR-G is rated for 200mA maximum output current. Use this part only in applications where output current requirement does not exceed 200mA. For 250mA requirements, select AP2139AK-1.2TRG1 or higher-current alternatives.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed—AP2139AK-1.2TRG1, AP7331-12WG-7, AP7335-12WG-7, RT9030A-12GB, and XC6221B122MR-G—maintain ROHS3 compliance matching the FT531AA specification.

Q: What packaging options are available for each substitute part?

A: AP2139AK-1.2TRG1 and RT9030A-12GB are supplied in Tape & Reel format in SOT-23-5 packaging. AP7331-12WG-7 is available in both Cut Tape and Digi-Reel in SOT-25 packaging. AP7335-12WG-7 is supplied in Tape & Reel in SOT-25 packaging. XC6221B122MR-G is supplied in Tape & Reel in SOT-25-5 packaging.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message