MIC5201-3.3BS TR Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The MIC5201-3.3BS TR is a linear voltage regulator IC from Microchip Technology designed to deliver a fixed 3.3V output at 150mA in a surface-mount SOT-223-3 package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The device provides positive fixed output configuration with integrated protection features including over-current, over-temperature, and reverse polarity protection, suitable for applications requiring stable 3.3V regulation from input sources up to 26V.

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
Package Type	SOT-223-3
Operating Temperature Range	-40°C ~ 125°C
Protection Features	Over Current, Over Temperature, Reverse Polarity
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts for the MIC5201-3.3BS TR are grouped based on the following critical parameters that determine functional compatibility:

Primary Substitution Criteria:

Fixed output voltage of 3.3V
Output current capability of 150mA or greater
Surface-mount SOT-223 package (SOT-223-3 or SOT-223-4)
Input voltage tolerance of 20V minimum
Operating temperature range overlap with -40°C to 125°C
Protection features including over-temperature and reverse polarity protection

Substitution Categories:

Category 1: Direct Equivalents (Same Output Current - 150mA) Parts maintaining 150mA output current with identical or superior electrical characteristics. These include MIC5201-3.3YS-TR (Microchip, active status), LT1121CST-3.3#PBF, LT1121CST-3.3#TRPBF, LT1121IST-3.3#PBF, and LT1121IST-3.3#TRPBF (Analog Devices). These provide pin-compatible or functionally equivalent solutions with active product status.

Category 2: Higher Current Capacity Substitutes (300mA - 500mA) Parts with increased output current capability suitable for applications requiring higher current delivery. These include TC1108-3.3VDBTR (Microchip, 300mA), LT1521CST-3.3#PBF, LT1521CST-3.3#TRPBF (Analog Devices, 300mA), LM2937IMP-3.3/NOPB, and LM2937IMPX-3.3/NOPB (Texas Instruments, 500mA). These parts maintain 3.3V output with enhanced current delivery while preserving SOT-223 packaging.

Parameter Comparison

Part Number	Manufacturer	Output Current	Input Voltage (Max)	Dropout Voltage	Quiescent Current	Operating Temp Range	Package	Status	RoHS Compliance
MIC5201-3.3BS TR	Microchip	150mA	26V	0.4V @ 150mA	400 µA	-40°C ~ 125°C	SOT-223-3	Obsolete	Non-compliant
MIC5201-3.3YS-TR	Microchip	150mA	26V	0.4V @ 150mA	400 µA	-40°C ~ 85°C	SOT-223-3	Active	ROHS3 Compliant
TC1108-3.3VDBTR	Microchip	300mA	6V	0.48V @ 300mA	90 µA	-40°C ~ 125°C	SOT-223-3	Active	ROHS3 Compliant
LM2937IMP-3.3/NOPB	Texas Instruments	500mA	26V	1V @ 500mA	10 mA	-40°C ~ 85°C	SOT-223-4	Active	ROHS3 Compliant
LM2937IMPX-3.3/NOPB	Texas Instruments	500mA	26V	1V @ 500mA	10 mA	-40°C ~ 85°C	SOT-223-4	Active	ROHS3 Compliant
LT1121CST-3.3#PBF	Analog Devices	150mA	30V	0.7V @ 150mA	50 µA	0°C ~ 125°C	SOT-223-3	Active	ROHS3 Compliant
LT1121CST-3.3#TRPBF	Analog Devices	150mA	30V	0.7V @ 150mA	50 µA	0°C ~ 125°C	SOT-223-3	Active	ROHS3 Compliant
LT1121IST-3.3#PBF	Analog Devices	150mA	30V	0.7V @ 150mA	50 µA	-40°C ~ 125°C	SOT-223-3	Active	ROHS3 Compliant
LT1121IST-3.3#TRPBF	Analog Devices	150mA	30V	0.7V @ 150mA	50 µA	-40°C ~ 125°C	SOT-223-3	Active	ROHS3 Compliant
LT1521CST-3.3#PBF	Analog Devices	300mA	20V	0.75V @ 300mA	25 µA	0°C ~ 125°C	SOT-223-3	Active	ROHS3 Compliant
LT1521CST-3.3#TRPBF	Analog Devices	300mA	20V	0.75V @ 300mA	25 µA	0°C ~ 125°C	SOT-223-3	Active	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Identical Current Rating): MIC5201-3.3YS-TR is the primary direct replacement from Microchip Technology. It maintains identical electrical specifications and SOT-223-3 packaging with active product status and ROHS3 compliance. Operating temperature range is reduced to -40°C ~ 85°C compared to the original -40°C ~ 125°C specification.

LT1121 series parts (LT1121CST-3.3#PBF, LT1121CST-3.3#TRPBF, LT1121IST-3.3#PBF, LT1121IST-3.3#TRPBF) from Analog Devices provide 150mA output with active status and ROHS3 compliance. LT1121IST variants support the full -40°C ~ 125°C temperature range. These parts feature higher input voltage tolerance (30V maximum) and lower quiescent current (50 µA).

For Enhanced Current Capability: TC1108-3.3VDBTR (Microchip, 300mA) and LT1521 series (LT1521CST-3.3#PBF, LT1521CST-3.3#TRPBF, 300mA) from Analog Devices provide doubled output current in SOT-223-3 packaging. Both maintain active status and ROHS3 compliance. TC1108-3.3VDBTR supports full -40°C ~ 125°C temperature range but has reduced input voltage tolerance (6V maximum). LT1521 series supports 20V input maximum with lower quiescent current (25 µA).

LM2937IMP-3.3/NOPB and LM2937IMPX-3.3/NOPB from Texas Instruments deliver 500mA output in SOT-223-4 packaging with 26V input tolerance and active status. These require PCB layout accommodation for the 4-pin package versus the original 3-pin configuration.

Compliance Considerations: All recommended substitutes carry ROHS3 compliance and REACH unaffected status. The original MIC5201-3.3BS TR is RoHS non-compliant, making migration to compliant alternatives necessary for new designs and production continuity.

Frequently Asked Questions (FAQ)

Q: Can MIC5201-3.3YS-TR directly replace MIC5201-3.3BS TR in existing designs? A: Yes, MIC5201-3.3YS-TR is a direct functional replacement with identical electrical specifications and SOT-223-3 packaging. The primary difference is reduced operating temperature range (-40°C ~ 85°C versus -40°C ~ 125°C) and active product status with ROHS3 compliance. Verify application temperature requirements before substitution.

Q: What is the difference between LT1121CST and LT1121IST variants? A: Both variants deliver 150mA output with identical electrical characteristics. The primary difference is operating temperature range: LT1121CST supports 0°C ~ 125°C, while LT1121IST supports -40°C ~ 125°C. Select based on application temperature requirements. Packaging variants (PBF for tube, TRPBF for tape & reel) do not affect electrical performance.

Q: Can I use TC1108-3.3VDBTR or LT1521 series as drop-in replacements? A: These 300mA parts are functionally compatible but not true drop-in replacements due to increased output current capability. PCB layout and thermal design may require adjustment. TC1108-3.3VDBTR has reduced input voltage tolerance (6V maximum) compared to the original 26V specification. LT1521 series supports 20V input maximum. Verify input voltage requirements before substitution.

Q: Why do LM2937 parts use SOT-223-4 packaging instead of SOT-223-3? A: The additional pin in SOT-223-4 packaging provides enhanced circuit protection features including mirror-image insertion protection and improved thermal characteristics for higher current delivery (500mA). PCB layout must accommodate the 4-pin configuration. Pin assignment differs from SOT-223-3 parts.

Q: Are all substitute parts ROHS3 compliant? A: Yes, all recommended substitute parts carry ROHS3 compliance certification. The original MIC5201-3.3BS TR is RoHS non-compliant. Migration to compliant alternatives is necessary for new production and designs subject to RoHS regulations.

Q: What is the impact of higher quiescent current in LM2937 parts? A: LM2937 series parts have 10 mA quiescent current compared to 400 µA in the original MIC5201-3.3BS TR. This increased standby current consumption may impact battery-powered or low-power applications. For low-power designs, LT1121 or LT1521 series with lower quiescent current (50 µA and 25 µA respectively) are preferred alternatives.

Q: Can I substitute parts with different input voltage ratings? A: Input voltage rating substitution requires verification that your application input voltage falls within the substitute part's maximum rating. TC1108-3.3VDBTR (6V maximum) is unsuitable for applications exceeding 6V input. LT1521 series (20V maximum) requires input voltage verification. LM2937 and LT1121 series support 26V and 30V input respectively, providing broader compatibility with the original 26V specification.

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