LM1973M/NOPB Equivalent & Substitute Parts

Part Overview

The LM1973M/NOPB is a 3-channel audio volume control IC manufactured by Texas Instruments, housed in a 20-SOIC surface mount package. This device is designed for consumer and professional audio applications requiring SPI-based digital volume adjustment with 76dB attenuation range. The product is currently obsolete, making identification of compatible substitute parts essential for ongoing system support and new design implementations.

Substiute Parts

LM1973M/NOPB

Texas InstrumentsIn Stock: 981LM1973M/NOPB Datasheet

Current PartRFQ

LM1972M/NOPB

National SemiconductorIn Stock: 6794LM1972M/NOPB Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution compatibility for the LM1973M/NOPB is determined by the following critical parameters:

• Package Type: Identical 20-SOIC form factor required for PCB layout compatibility
• Interface Protocol: SPI interface maintained for firmware and control circuit compatibility
• Supply Voltage Range: 4.5V ~ 12V compatibility ensures power supply interchangeability
• Operating Temperature Range: 0°C ~ 70°C maintains thermal performance specifications
• Mounting Type: Surface mount technology consistency

The LM1972M/NOPB qualifies as a manufacturer-recommended substitute despite having 2 channels instead of 3, as it maintains identical electrical interface, package, supply voltage, and operating temperature specifications. The channel reduction represents a functional trade-off that may require circuit redesign but does not prevent electrical substitution at the component level.

Parameter Comparison

Engineering Selection Recommendations

The LM1972M/NOPB is designated as the manufacturer-recommended substitute for the obsolete LM1973M/NOPB based on the following criteria:

• Regulatory Compliance: Both parts maintain ROHS3 compliance and REACH unaffected status, satisfying environmental and regulatory requirements for equivalent component selection.

• Active Production Status: The LM1972M/NOPB remains in active production with documented inventory availability (6744 units), ensuring supply chain continuity compared to the obsolete LM1973M/NOPB.

• Electrical Interface Compatibility: Identical SPI interface, supply voltage range (4.5V ~ 12V), and operating temperature specifications (0°C ~ 70°C) enable direct electrical substitution without power supply or thermal management modifications.

• Package Compatibility: Both devices use the 20-SOIC package with identical physical dimensions (0.295", 7.50mm width), allowing direct PCB footprint reuse.

• Functional Trade-off: The reduction from 3 channels to 2 channels requires circuit redesign and firmware modification but does not prevent component-level substitution. The LM1972M/NOPB provides 78dB attenuation versus the original 76dB, offering improved dynamic range.

Frequently Asked Questions (FAQ)

Q: Can the LM1972M/NOPB be used as a direct drop-in replacement for the LM1973M/NOPB?

A: The LM1972M/NOPB shares identical package, interface protocol, and electrical specifications, enabling physical PCB placement without modification. However, the reduction from 3 channels to 2 channels requires circuit redesign and firmware updates to accommodate the functional change.

Q: Are there any supply voltage or thermal compatibility issues when substituting the LM1972M/NOPB?

A: No. Both devices operate within the identical 4.5V ~ 12V supply range and 0°C ~ 70°C temperature specification, eliminating power supply or thermal management concerns.

Q: Does the LM1972M/NOPB meet the same environmental and regulatory standards?

A: Yes. Both the LM1973M/NOPB and LM1972M/NOPB are ROHS3 compliant and REACH unaffected, meeting equivalent environmental and regulatory requirements.

Q: What is the significance of the 78dB attenuation in the LM1972M/NOPB versus 76dB in the original part?

A: The LM1972M/NOPB provides 2dB additional attenuation range, offering improved dynamic range control. This represents a performance enhancement rather than a limitation for audio volume control applications.

Q: Is the 20-SOIC package identical between both devices?

A: Yes. Both devices use the 20-SOIC package with identical physical dimensions (0.295", 7.50mm width), ensuring complete PCB footprint compatibility.

Q: What is the moisture sensitivity level difference, and does it affect substitution?

A: The LM1973M/NOPB specifies MSL 3 (168 hours). The LM1972M/NOPB moisture sensitivity data is not provided in the available specifications. Verify MSL requirements with the component supplier if moisture exposure during storage or assembly is a concern.