FT533GA Linear Voltage Regulator IC Equivalent & Substitute Parts

Part Overview

The FT533GA is a linear voltage regulator IC manufactured by Fremont Micro Devices Ltd, designed to deliver a fixed 2.8V output at 400mA in a surface-mount SOT-23-5 package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The FT533GA features enable control, over-current protection, and operates across the industrial temperature range of -40°C to 85°C.

Key Parameters

Parameter	Value
Manufacturer	Fremont Micro Devices Ltd
Part Number	FT533GA
Category	Power Management (PMIC)
Product Status	Obsolete
Output Voltage (Fixed)	2.8V
Output Current	400mA
Input Voltage (Max)	6V
Dropout Voltage (Max)	0.42V @ 400mA
Quiescent Current	65 µA
Package	SOT-23-5 (SC-74A)
Operating Temperature	-40°C to 85°C
Protection Features	Over Current
Control Features	Enable
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the FT533GA is determined by the following critical parameters:

Output voltage fixed at 2.8V
SOT-23-5 package compatibility
Surface-mount mounting type
Operating temperature range -40°C to 85°C
Enable control feature
Over-current protection

Substitute parts are grouped into two categories based on output current capability:

Group 1: Reduced Current (300mA) — AP2125K-2.8TRE1, AP2125K-2.8TRG1, AP2127K-2.8TRG1 These parts deliver 300mA output current, lower than the original 400mA specification. Substitution is valid for applications where load current does not exceed 300mA.

Group 2: Enhanced Current (500mA) — RT9013-28GB This part delivers 500mA output current, exceeding the original 400mA specification. Substitution is valid for applications requiring higher current capacity within the same voltage and package constraints.

Parameter Comparison

Parameter	FT533GA	AP2125K-2.8TRE1	AP2125K-2.8TRG1	AP2127K-2.8TRG1	RT9013-28GB
Manufacturer	Fremont Micro Devices Ltd	Diodes Incorporated	Diodes Incorporated	Diodes Incorporated	Richtek USA Inc.
Output Voltage (Fixed)	2.8V	2.8V	2.8V	2.8V	2.8V
Output Current	400mA	300mA	300mA	300mA	500mA
Input Voltage (Max)	6V	6V	6V	6V	5.5V
Dropout Voltage (Max)	0.42V @ 400mA	0.3V @ 300mA	0.3V @ 300mA	0.3V @ 300mA	0.4V @ 500mA
Quiescent Current	65 µA	90 µA	90 µA	90 µA	50 µA
Package	SOT-23-5	SOT-23-5	SOT-23-5	SOT-23-5	SOT-23-5
Operating Temperature	-40°C to 85°C	-40°C to 85°C	-40°C to 85°C	-40°C to 85°C	-40°C to 85°C
Protection Features	Over Current	Over Current, Over Temperature	Over Current, Over Temperature	Over Current, Over Temperature	Over Current, Over Temperature
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

All substitute parts listed are ROHS3 compliant and maintain active product status, ensuring long-term availability and supply chain stability compared to the obsolete FT533GA.

For applications with load current ≤ 300mA: AP2125K-2.8TRG1 is the preferred substitute. This part is actively manufactured by Diodes Incorporated with 39,100 units in stock, available in Cut Tape and Digi-Reel packaging. It provides identical output voltage and package compatibility with enhanced over-temperature protection.

For applications with load current between 300mA and 400mA: AP2125K-2.8TRE1 or AP2127K-2.8TRG1 are suitable alternatives. Both maintain the 2.8V output and SOT-23-5 package with active product status and full compliance certifications.

For applications requiring load current up to 500mA: RT9013-28GB from Richtek USA Inc. provides the highest output current capacity at 500mA. This part has the largest inventory (423,053 units) and lowest quiescent current (50 µA). Note that the maximum input voltage is 5.5V compared to 6V for other substitutes.

All substitute parts maintain the same operating temperature range and enable control feature as the original FT533GA.

Frequently Asked Questions (FAQ)

Q: Can AP2125K-2.8TRG1 directly replace FT533GA in existing designs? A: Yes, for applications where load current does not exceed 300mA. The part shares identical output voltage (2.8V), package (SOT-23-5), operating temperature range, and control features. Pin-to-pin compatibility is maintained.

Q: What is the key difference between the three Diodes Incorporated substitutes? A: AP2125K-2.8TRE1 is supplied in Cut Tape packaging, AP2125K-2.8TRG1 in Cut Tape and Digi-Reel, and AP2127K-2.8TRG1 in Tape & Reel. All three deliver 300mA output current. AP2127K-2.8TRG1 does not include an enable control feature.

Q: Why does RT9013-28GB have a lower maximum input voltage (5.5V vs 6V)? A: RT9013-28GB is specified with a 5.5V maximum input voltage. Applications using input voltages between 5.5V and 6V must use AP2125 or AP2127 series substitutes instead.

Q: Are all substitute parts RoHS compliant? A: Yes. All substitute parts are ROHS3 compliant, matching the compliance status of the original FT533GA.

Q: Which substitute has the best quiescent current performance? A: RT9013-28GB has the lowest quiescent current at 50 µA, compared to 65 µA for FT533GA and 90 µA for AP2125/AP2127 series. This is beneficial for battery-powered or low-power standby applications.

Q: Can I use a 300mA substitute in a design originally specified for 400mA? A: Only if the actual load current in your application is confirmed to be ≤ 300mA. Exceeding the rated output current will trigger over-current protection and may cause the regulator to shut down or limit output.

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