LM77CIMM-3 Temperature Sensor Equivalent & Substitute Parts

Part Overview

The LM77CIMM-3 is a digital temperature sensor manufactured by Texas Instruments, designed for local temperature monitoring across a -55°C to 125°C range with 9-bit resolution and I2C output interface. The device operates on supply voltages between 3V and 5.5V and features programmable limit thresholds, output switching capability, and shutdown mode functionality.

This part is classified as obsolete. Identifying equivalent and substitute components is necessary to ensure design continuity, maintain supply chain reliability, and support long-term product availability for applications currently utilizing the LM77CIMM-3.

Substiute Parts

LM77CIMM-3

Texas InstrumentsIn Stock: 2490LM77CIMM-3 Datasheet

Current PartRFQ

LM77CIMM-3/NOPB

Texas InstrumentsIn Stock: 2362LM77CIMM-3/NOPB Datasheet

DirectRFQ

MCP9844T-BE/MNY

Microchip TechnologyIn Stock: 6644MCP9844T-BE/MNY Datasheet

MFR RecommendedRFQ

MCP9844T-BE/MNYAA

Microchip TechnologyIn Stock: 1241MCP9844T-BE/MNYAA Datasheet

MFR RecommendedRFQ

MCP9844T-BE/MNYAB

Microchip TechnologyIn Stock: 6664MCP9844T-BE/MNYAB Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the LM77CIMM-3 is determined by the following critical parameters:

Primary Substitution Criteria:

• Output interface type (I2C serial communication)
• Local temperature sensing capability
• Operating temperature range overlap (-55°C to 125°C minimum)
• Supply voltage compatibility (3V to 5.5V range)
• Resolution (9-bit or equivalent)
• Surface mount packaging

Substitute Categories:

Category 1: Direct Equivalent (Same Manufacturer) The LM77CIMM-3/NOPB is a direct equivalent from Texas Instruments, maintaining identical electrical specifications and functional characteristics. The primary distinction is packaging format (Cut Tape & Digi-Reel versus standard packaging) and improved RoHS3 compliance status.

Category 2: Cross-Manufacturer Alternatives (Microchip Technology) The MCP9844T-BE series (MCP9844T-BE/MNY, MCP9844T-BE/MNYAA, MCP9844T-BE/MNYAB) represents functional alternatives from Microchip Technology. These devices provide I2C output, internal temperature sensing, and overlapping operating temperature ranges. Key parameter differences include reduced supply voltage range (1.7V to 3.6V versus 3V to 5.5V) and different package geometry (8-TDFN 2x3 versus 8-VSSOP).

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Preferred for Existing Designs): The LM77CIMM-3/NOPB is the recommended direct substitute. It maintains identical electrical specifications and functional characteristics while providing improved RoHS3 compliance status. This option minimizes design validation requirements and ensures pin-for-pin compatibility.

For New Designs or Redesign Scenarios: The MCP9844T-BE series (MCP9844T-BE/MNY, MCP9844T-BE/MNYAA, MCP9844T-BE/MNYAB) represents active, production-supported alternatives. These devices offer:

• Active product status with ongoing manufacturer support
• RoHS3 compliance
• I2C interface compatibility with the original design
• Overlapping operating temperature range for most applications (-40°C to 125°C)

Critical Design Considerations:

• Supply voltage range differs between LM77 series (3V to 5.5V) and MCP9844 series (1.7V to 3.6V). Verify power supply specifications in target application.
• Package geometry differs (8-VSSOP versus 8-TDFN 2x3). PCB layout modifications are required for cross-manufacturer substitution.
• Lower temperature limit of MCP9844 series is -40°C versus -55°C for LM77 series. Applications requiring operation below -40°C must use LM77CIMM-3/NOPB.

Frequently Asked Questions (FAQ)

Q: Can the MCP9844T-BE series directly replace the LM77CIMM-3 without PCB modifications? A: No. While both devices provide I2C temperature sensing, the package types differ (8-VSSOP versus 8-TDFN 2x3). PCB layout and footprint modifications are required. Additionally, supply voltage ranges differ, requiring verification of power supply specifications.

Q: What is the minimum operating temperature difference between the LM77CIMM-3 and MCP9844T-BE series? A: The LM77CIMM-3 operates to -55°C, while the MCP9844T-BE series operates to -40°C. Applications requiring temperature monitoring below -40°C must use the LM77CIMM-3 or LM77CIMM-3/NOPB.

Q: Are all MCP9844T-BE variants (MNY, MNYAA, MNYAB) functionally equivalent? A: Yes. The variants differ in packaging format (Cut Tape & Digi-Reel versus Tape & Reel) and inventory availability. Electrical specifications and functional characteristics are identical across all three variants.

Q: Why is the LM77CIMM-3 classified as obsolete? A: The LM77CIMM-3 is no longer in active production. The LM77CIMM-3/NOPB provides an equivalent alternative with improved compliance status. For new designs, active alternatives such as the MCP9844T-BE series are recommended.

Q: What supply voltage range should be used when substituting with MCP9844T-BE series? A: The MCP9844T-BE series operates on 1.7V to 3.6V. If the original design uses 5V supply, voltage regulation or level shifting may be required. Verify power supply specifications and design requirements before implementation.

Q: Is the I2C interface protocol identical between LM77CIMM-3 and MCP9844T-BE? A: Both devices use I2C serial communication. However, register maps and command structures may differ. Firmware or software modifications may be required to accommodate different device protocols and register definitions.