MIC5209-3.3BS TR Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The MIC5209-3.3BS TR is a linear voltage regulator IC from Microchip Technology designed to deliver a fixed 3.3V output at 500mA in a SOT-223-3 surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The MIC5209-3.3BS TR provides positive fixed output regulation with integrated over-current, over-temperature, and reverse polarity protection across an operating temperature range of -40°C to 125°C.

Key Parameters

Parameter	Value
Manufacturer	Microchip Technology
Part Number	MIC5209-3.3BS TR
Output Voltage	3.3V Fixed
Output Current	500mA
Input Voltage (Max)	16V
Dropout Voltage	0.6V @ 500mA
Quiescent Current	170 µA
Package	SOT-223-3
Operating Temperature	-40°C to 125°C
Protection Features	Over Current, Over Temperature, Reverse Polarity
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the MIC5209-3.3BS TR is determined by the following critical parameters: fixed 3.3V output voltage, 500mA output current capability, SOT-223 package form factor, surface mount mounting type, and operating temperature range of -40°C to 125°C. All substitute parts must maintain these core electrical and mechanical specifications to ensure direct functional replacement without circuit redesign.

Substitute parts are grouped into two categories:

Direct Microchip Equivalents: Parts that maintain identical electrical specifications and packaging, differing only in product status or packaging format (tape & reel vs. cut tape).

Cross-Manufacturer Alternatives: Parts from Texas Instruments and Analog Devices that meet or exceed the electrical requirements while maintaining SOT-223 package compatibility and the required operating temperature range.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout Voltage	Quiescent Current	Package	Operating Temp	Product Status
MIC5209-3.3BS TR	Microchip	3.3V	500mA	16V	0.6V @ 500mA	170 µA	SOT-223-3	-40°C to 125°C	Obsolete
MIC5209-3.3YS-TR	Microchip	3.3V	500mA	16V	0.6V @ 500mA	170 µA	SOT-223-3	-40°C to 125°C	Active
MCP1825ST-3302E/DB	Microchip	3.3V	500mA	6V	0.35V @ 500mA	220 µA	SOT-223-3	-40°C to 125°C	Active
LM2937IMP-3.3/NOPB	Texas Instruments	3.3V	500mA	26V	1V @ 500mA	10 mA	SOT-223-4	-40°C to 85°C	Active
LM2937IMPX-3.3/NOPB	Texas Instruments	3.3V	500mA	26V	1V @ 500mA	10 mA	SOT-223-4	-40°C to 85°C	Active
LM3940IMP-3.3/NOPB	Texas Instruments	3.3V	1A	7.5V	0.2V @ 100mA	Not specified	SOT-223-4	-40°C to 125°C	Active
LM3940IMPX-3.3/NOPB	Texas Instruments	3.3V	1A	7.5V	0.2V @ 100mA	Not specified	SOT-223-4	-40°C to 125°C	Active
LT1129CST-3.3#PBF	Analog Devices	3.3V	700mA	30V	0.7V @ 700mA	70 µA	SOT-223-3	0°C to 125°C	Active
LT1129CST-3.3#TRPBF	Analog Devices	3.3V	700mA	30V	0.7V @ 700mA	70 µA	SOT-223-3	0°C to 125°C	Active
LT1129IST-3.3#PBF	Analog Devices	3.3V	700mA	30V	0.7V @ 700mA	70 µA	SOT-223-3	-40°C to 125°C	Active
LT1129IST-3.3#TRPBF	Analog Devices	3.3V	700mA	30V	0.7V @ 700mA	70 µA	SOT-223-3	-40°C to 125°C	Active

Engineering Selection Recommendations

Primary Recommendation: MIC5209-3.3YS-TR

The MIC5209-3.3YS-TR is the direct active equivalent to the obsolete MIC5209-3.3BS TR. It maintains identical electrical specifications, output current rating, dropout voltage, and quiescent current characteristics. The only difference is product status (active vs. obsolete) and packaging format (cut tape & Digi-Reel vs. tape & reel). This part is ROHS3 compliant and carries the same MSL rating. Selection of this part requires no circuit modifications and provides the most direct replacement path.

Secondary Recommendation: LT1129IST-3.3#TRPBF

The LT1129IST-3.3#TRPBF from Analog Devices provides enhanced performance characteristics while maintaining SOT-223-3 package compatibility. It delivers 700mA output current (exceeding the 500mA requirement), operates across the full -40°C to 125°C temperature range, and features a lower quiescent current of 70 µA. The higher input voltage rating (30V vs. 16V) and improved dropout voltage characteristics make this suitable for applications requiring greater design margin. This part is ROHS3 compliant with unlimited MSL rating.

Alternative for Higher Current Applications: LM3940IMP-3.3/NOPB

The LM3940IMP-3.3/NOPB delivers 1A output current in a SOT-223-4 package, suitable for designs requiring current capacity beyond 500mA. It maintains the -40°C to 125°C operating temperature range and is ROHS3 compliant. The SOT-223-4 package requires PCB layout modification compared to the SOT-223-3 footprint of the original part.

All recommended substitutes are active products with current manufacturing status and full compliance certifications (ROHS3, REACH Unaffected, EAR99).

Frequently Asked Questions (FAQ)

Q: Can MIC5209-3.3YS-TR be used as a direct drop-in replacement for MIC5209-3.3BS TR?

A: Yes. The MIC5209-3.3YS-TR is electrically and mechanically identical to the MIC5209-3.3BS TR. Both parts feature the same 3.3V output, 500mA current rating, 0.6V dropout voltage, and SOT-223-3 package. The only differences are product status and packaging format. No circuit modifications are required.

Q: What is the difference between SOT-223-3 and SOT-223-4 packages?

A: SOT-223-3 contains three pins (input, output, ground), while SOT-223-4 contains four pins (input, output, ground, and an additional pin). Parts specified for SOT-223-4 packages require different PCB footprints and cannot be used on boards designed for SOT-223-3 without layout modification.

Q: Why does the LT1129IST-3.3#TRPBF have a higher quiescent current (70 µA) compared to the MIC5209-3.3BS TR (170 µA)?

A: The LT1129IST-3.3#TRPBF actually has lower quiescent current at 70 µA, which is superior to the original part's 170 µA. This represents improved power efficiency during standby operation.

Q: Can I use LM3940IMP-3.3/NOPB in place of MIC5209-3.3BS TR?

A: The LM3940IMP-3.3/NOPB is functionally compatible but requires PCB layout changes. It uses a SOT-223-4 package instead of SOT-223-3, and delivers 1A output current instead of 500mA. The operating temperature range matches (-40°C to 125°C). Use this part only if your PCB design can accommodate the different package footprint.

Q: What does ROHS3 compliance mean for these parts?

A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements, restricting the use of specific hazardous materials in electrical and electronic equipment. All recommended substitutes carry ROHS3 compliance.

Q: Are there any temperature range limitations I should consider?

A: The LT1129CST-3.3#PBF and LT1129CST-3.3#TRPBF variants operate from 0°C to 125°C, which is narrower than the original part's -40°C to 125°C range. For applications requiring full -40°C operation, use the LT1129IST-3.3 variants instead.

Q: What is the MSL (Moisture Sensitivity Level) rating and why does it matter?

A: MSL indicates how sensitive a component is to moisture during storage and handling. The original MIC5209-3.3BS TR has MSL 3 (168 hours), while most active substitutes have MSL 1 (unlimited). Lower MSL ratings provide greater flexibility in storage and handling without requiring special moisture control measures.

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