MCP1811AT-033/LT Equivalent & Substitute Parts

Part Overview

The MCP1811AT-033/LT is a linear voltage regulator IC from Microchip Technology designed for positive fixed 3.3V output applications with 150mA current capacity in SC-70-5 surface mount packaging. This device is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing design support and production continuity. The MCP1811 series has been superseded by newer generations within the Microchip linear regulator portfolio, requiring component substitution for new procurement and redesign scenarios.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	3.3V
Output Current	150mA
Input Voltage (Max)	5.5V
Dropout Voltage (Max)	0.6V @ 150mA
Output Configuration	Positive Fixed
Control Features	Enable
Protection Features	Over Current
Operating Temperature Range	-40°C to 85°C
Mounting Type	Surface Mount
Package Type	SC-70-5 (5-TSSOP)

Substitute Part Grouping Explanation

Substitution of the MCP1811AT-033/LT is determined by the following critical parameters:

Fixed output voltage of 3.3V
Output current capacity of 150mA minimum
Maximum input voltage tolerance of 5.5V or greater
Positive output configuration with fixed regulation
Enable control feature availability
Surface mount technology compatibility
Operating temperature range of -40°C to 85°C

The MCP1711T-33I/OT qualifies as a direct functional substitute based on matching all critical electrical specifications and control features. While package geometry differs (SOT-23-5 versus SC-70-5), both are industry-standard surface mount packages with equivalent pin functionality and thermal performance for this current class.

Parameter Comparison

Parameter	MCP1811AT-033/LT	MCP1711T-33I/OT	Compatibility
Output Voltage (Fixed)	3.3V	3.3V	Identical
Output Current	150mA	150mA	Identical
Input Voltage (Max)	5.5V	6V	Substitute exceeds specification
Dropout Voltage (Max)	0.6V @ 150mA	0.67V @ 150mA	Substitute within acceptable margin
Quiescent Current (Iq)	0.5 µA	1.27 µA	Substitute higher, acceptable for most applications
Output Configuration	Positive Fixed	Positive Fixed	Identical
Control Features	Enable	Enable	Identical
Operating Temperature	-40°C to 85°C	-40°C to 85°C	Identical
Mounting Type	Surface Mount	Surface Mount	Identical
Package Type	SC-70-5 (5-TSSOP)	SOT-23-5 (SC-74A)	Different footprint, same pin count
Product Status	Obsolete	Active	Substitute actively manufactured
RoHS Compliance	Not specified	ROHS3 Compliant	Substitute meets current compliance

Engineering Selection Recommendations

The MCP1711T-33I/OT is the recommended substitute for the obsolete MCP1811AT-033/LT based on the following factors:

Both devices are manufactured by Microchip Technology, ensuring consistent design philosophy and reliability standards
The MCP1711T-33I/OT maintains active product status with established supply chain availability (10,083 pcs in stock versus 964 pcs for the obsolete part)
Electrical specifications are functionally equivalent across all critical parameters: 3.3V fixed output, 150mA current capacity, and identical operating temperature range
The substitute device exceeds input voltage tolerance (6V versus 5.5V), providing additional design margin
ROHS3 compliance of the substitute aligns with current regulatory requirements
Package substitution from SC-70-5 to SOT-23-5 requires PCB layout modification but maintains identical pin functionality and thermal characteristics for this current class

Frequently Asked Questions (FAQ)

Q: Can the MCP1711T-33I/OT directly replace the MCP1811AT-033/LT without circuit modification?

A: Electrical substitution is direct. However, PCB layout modification is required due to different package footprints (SC-70-5 versus SOT-23-5). Pin functionality and signal assignments remain identical.

Q: What is the impact of the higher quiescent current in the MCP1711T-33I/OT?

A: The MCP1711T-33I/OT draws 1.27 µA versus 0.5 µA for the original part. This 0.77 µA difference is negligible in most applications and only becomes significant in ultra-low-power battery-operated designs where standby current is critical.

Q: Does the slightly higher dropout voltage of the MCP1711T-33I/OT affect circuit performance?

A: The dropout voltage difference is 0.07V (0.67V versus 0.6V at 150mA). This marginal increase is acceptable for most applications. Verify that your input voltage headroom remains sufficient for your specific operating conditions.

Q: Why is the MCP1811AT-033/LT classified as obsolete?

A: The MCP1811 series has been superseded by the MCP1711 series within Microchip's linear regulator portfolio. The newer generation offers improved specifications, better compliance certifications, and continued manufacturing support.

Q: Is the SOT-23-5 package suitable for my application if the original design used SC-70-5?

A: Both packages are industry-standard surface mount packages with equivalent thermal performance for 150mA applications. SOT-23-5 is more widely available and offers slightly better thermal characteristics. PCB layout redesign is required to accommodate the different footprint.

Q: What certifications does the substitute part carry?

A: The MCP1711T-33I/OT is ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory standards. The original MCP1811AT-033/LT certification status is not specified in available documentation.

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