MIC5201-3.3BS Equivalent & Substitute Parts

Part Overview

The MIC5201-3.3BS is a linear voltage regulator IC from Microchip Technology designed to deliver a fixed 3.3V output at 150mA in a SOT-223-3 surface mount package. This part is classified as obsolete, which necessitates identification of active equivalent and substitute components for new designs or production continuity. The MIC5201-3.3BS 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
Output Voltage (Fixed)	3.3V
Output Current	150mA
Input Voltage (Max)	26V
Dropout Voltage	0.4V @ 150mA
Quiescent Current	400 µA
PSRR	75dB (100Hz)
Package	SOT-223-3
Operating Temperature	-40°C ~ 125°C
Protection Features	Over Current, Over Temperature, Reverse Polarity
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the MIC5201-3.3BS is determined by the following critical parameters:

Primary Substitution Criteria:

Fixed output voltage of 3.3V
Output current capability of 150mA or greater
SOT-223-3 or SOT-223-4 package compatibility
Input voltage rating of 26V or higher
Operating temperature range supporting -40°C to 125°C
Surface mount technology

Grouping Logic:

Group 1 – Direct Replacement (150mA Output): Parts with 150mA output current rating in SOT-223-3 package. These provide pin-compatible substitution with identical electrical performance.

Group 2 – Higher Current Alternatives (300mA Output): Parts rated for 300mA output current. These offer increased current capacity while maintaining 3.3V fixed output and SOT-223-3 packaging. Suitable when design margin or future current requirements necessitate higher capacity.

Group 3 – Enhanced Current Alternatives (500mA+ Output): Parts rated for 500mA or greater output current in SOT-223-4 package. These provide significantly higher current delivery and are selected when application requirements exceed 150mA or when design flexibility is prioritized.

All substitute parts maintain positive fixed output configuration, 3.3V output voltage, and surface mount technology. Compliance status and product lifecycle state are secondary selection factors based on application requirements.

Parameter Comparison

Part Number	Manufacturer	Output Current	Input Voltage (Max)	Dropout Voltage	Quiescent Current	Package	Operating Temp	Product Status	RoHS Status
MIC5201-3.3BS	Microchip	150mA	26V	0.4V @ 150mA	400 µA	SOT-223-3	-40°C ~ 125°C	Obsolete	Non-compliant
MIC5201-3.3YS	Microchip	150mA	26V	0.4V @ 150mA	400 µA	SOT-223-3	-40°C ~ 85°C	Active	ROHS3 Compliant
TC1108-3.3VDBTR	Microchip	300mA	6V	0.48V @ 300mA	90 µA	SOT-223-3	-40°C ~ 125°C	Active	ROHS3 Compliant
LM2937IMP-3.3/NOPB	Texas Instruments	500mA	26V	1V @ 500mA	10 mA	SOT-223-4	-40°C ~ 85°C	Active	ROHS3 Compliant
LM2937IMPX-3.3/NOPB	Texas Instruments	500mA	26V	1V @ 500mA	10 mA	SOT-223-4	-40°C ~ 85°C	Active	ROHS3 Compliant
LM3940IMP-3.3/NOPB	Texas Instruments	1A	7.5V	0.2V @ 100mA	Not specified	SOT-223-4	-40°C ~ 125°C	Active	ROHS3 Compliant
LT1121CST-3.3#PBF	Analog Devices	150mA	30V	0.7V @ 150mA	50 µA	SOT-223-3	0°C ~ 125°C	Active	ROHS3 Compliant
LT1121CST-3.3#TRPBF	Analog Devices	150mA	30V	0.7V @ 150mA	50 µA	SOT-223-3	0°C ~ 125°C	Active	ROHS3 Compliant
LT1121IST-3.3#PBF	Analog Devices	150mA	30V	0.7V @ 150mA	50 µA	SOT-223-3	-40°C ~ 125°C	Active	ROHS3 Compliant
LT1121IST-3.3#TRPBF	Analog Devices	150mA	30V	0.7V @ 150mA	50 µA	SOT-223-3	-40°C ~ 125°C	Active	ROHS3 Compliant
LT1521CST-3.3#PBF	Analog Devices	300mA	20V	0.75V @ 300mA	25 µA	SOT-223-3	0°C ~ 125°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement with Identical Specifications:

Select MIC5201-3.3YS when pin-for-pin compatibility and identical electrical performance are required. This part maintains the same 150mA output current, 0.4V dropout voltage, and SOT-223-3 package as the obsolete MIC5201-3.3BS. The primary difference is active product status and ROHS3 compliance, making it the preferred direct substitute for existing designs.

For Extended Temperature Range (-40°C to 125°C):

LT1121IST-3.3#PBF and LT1121IST-3.3#TRPBF from Analog Devices provide the full -40°C to 125°C operating range matching the original part. These parts deliver 150mA output current in SOT-223-3 packaging with higher input voltage rating (30V) and lower quiescent current (50 µA). ROHS3 compliance and active product status support long-term availability.

For Increased Current Capacity (300mA):

TC1108-3.3VDBTR (Microchip) or LT1521CST-3.3#PBF (Analog Devices) are selected when 300mA output current is required. Both maintain SOT-223-3 packaging and 3.3V fixed output. TC1108-3.3VDBTR supports -40°C to 125°C operation, while LT1521CST-3.3#PBF operates from 0°C to 125°C. Both are ROHS3 compliant and active products.

For Maximum Current Capacity (500mA+):

LM2937IMP-3.3/NOPB or LM2937IMPX-3.3/NOPB (Texas Instruments) deliver 500mA output current with 26V input rating. These parts require SOT-223-4 package (4-pin versus 3-pin) and operate from -40°C to 85°C. LM3940IMP-3.3/NOPB (Texas Instruments) provides 1A output current with lower dropout voltage (0.2V @ 100mA) and extended temperature range (-40°C to 125°C), also in SOT-223-4 package. These options are selected when application requirements exceed 150mA and PCB layout accommodates the 4-pin package.

Compliance Considerations:

All recommended active substitutes are ROHS3 compliant. The original MIC5201-3.3BS is RoHS non-compliant. For applications requiring RoHS compliance, all listed active alternatives satisfy this requirement.

Frequently Asked Questions (FAQ)

Q: Can MIC5201-3.3YS be used as a direct replacement for MIC5201-3.3BS?

A: Yes. MIC5201-3.3YS is electrically and mechanically identical to MIC5201-3.3BS, with the same 150mA output current, 0.4V dropout voltage, and SOT-223-3 package. The primary differences are active product status and ROHS3 compliance. Operating temperature range differs slightly (-40°C to 85°C versus -40°C to 125°C), which may be a consideration for applications requiring the full 125°C upper limit.

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

A: SOT-223-3 is a 3-pin package (input, output, ground), while SOT-223-4 is a 4-pin package with an additional pin for enhanced thermal performance or additional functionality. Parts specified for SOT-223-4 (such as LM2937 and LM3940 series) cannot be directly substituted into SOT-223-3 footprints without PCB redesign.

Q: Why do some substitutes have higher quiescent current?

A: Quiescent current varies by design architecture and process technology. LM2937 series parts specify 10 mA quiescent current, which is higher than the MIC5201-3.3BS (400 µA). This difference is acceptable in applications where quiescent current is not a critical design constraint. For low-power applications, LT1121 or LT1521 series with lower quiescent current (50 µA and 25 µA respectively) are preferred.

Q: Can I use a higher current-rated part (300mA or 500mA) in place of the 150mA MIC5201-3.3BS?

A: Yes. Higher current-rated regulators are backward compatible with lower current applications. The regulator will deliver the required 150mA without stress. This approach provides design margin and future scalability. However, package changes (SOT-223-3 to SOT-223-4) require PCB layout modifications.

Q: What is the significance of product status (Active vs. Obsolete)?

A: Active products have guaranteed long-term availability and manufacturer support. Obsolete products are no longer manufactured and existing inventory is finite. For new designs or production continuity, active substitutes are strongly preferred to avoid future supply chain disruptions.

Q: Are all listed substitutes ROHS3 compliant?

A: All active substitute parts listed are ROHS3 compliant. The original MIC5201-3.3BS is RoHS non-compliant. If RoHS compliance is a design requirement, any of the active alternatives satisfy this criterion.

Q: How does dropout voltage affect part selection?

A: Dropout voltage determines the minimum input-to-output voltage differential required for regulation. The MIC5201-3.3BS specifies 0.4V @ 150mA. Substitutes with higher dropout voltage (such as LT1121 at 0.7V) require proportionally higher input voltage to maintain regulation. For applications with tight input voltage margins, lower dropout alternatives (LM3940 at 0.2V @ 100mA) are preferred.

Q: What is PSRR and why does it vary among substitutes?

A: Power Supply Rejection Ratio (PSRR) measures the regulator's ability to reject input voltage ripple and noise. The MIC5201-3.3BS specifies 75dB @ 100Hz. Higher PSRR values indicate better noise rejection. Not all substitutes specify PSRR, which may indicate this parameter is not critical for the application or is specified at different test conditions. For noise-sensitive applications, parts with specified PSRR should be prioritized.

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