HM-31308-P113 Equivalent & Substitute Parts

Part Overview

The HM-31308-P113 is an electret condenser microphone manufactured by Knowles, designed for analog audio capture applications requiring compact form factors and low-voltage operation. This microphone operates across a frequency range of 100 Hz to 10 kHz with a sensitivity of -32dB ±3dB at 94dB SPL, making it suitable for voice and general audio applications. The device is currently classified as obsolete, necessitating identification of functionally equivalent alternatives for ongoing production and maintenance requirements.

Substiute Parts

HM-31308-P113

KnowlesIn Stock: 1008HM-31308-P113 Datasheet

Current PartRFQ

CMC-2742WBL-25L

CUI DevicesIn Stock: 30053CMC-2742WBL-25L Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the HM-31308-P113 is determined by the following critical parameters:

Form Factor Compatibility: The substitute part must maintain the same circular shape with 0.236" (6.00mm) diameter to ensure mechanical fit within existing enclosures and PCB layouts.

Electrical Interface: Both the main part and substitute must provide analog output with wire lead termination, enabling direct connection to existing signal conditioning circuits.

Microphone Type: Electret condenser technology is required to maintain consistent acoustic performance characteristics and power supply requirements.

Voltage and Current Specifications: The substitute must operate within or encompass the voltage range of 2.5 V to 5.5 V and supply current of 500 µA to ensure compatibility with existing power delivery systems.

Frequency Response and Sensitivity: While the substitute may extend the frequency range or alter sensitivity characteristics, the core audio capture capability must remain functional for the intended application.

Compliance Standards: Both parts must maintain ROHS3 compliance and equivalent environmental ratings to satisfy regulatory and reliability requirements.

Parameter Comparison

Engineering Selection Recommendations

The CMC-2742WBL-25L from CUI Devices is identified as the primary substitute for the obsolete HM-31308-P113. This substitution is supported by the following engineering factors:

Mechanical Compatibility: Both parts share identical diameter specifications (0.236" / 6.00mm) and circular form factor, ensuring compatibility with existing mechanical mounting and PCB layouts. The CMC-2742WBL-25L exhibits a maximum height of 0.161" (4.10mm) compared to 0.142" (3.60mm) for the original part, representing a 0.019" (0.50mm) increase that must be evaluated within specific enclosure constraints.

Electrical Interface: Both microphones provide analog output via wire lead termination, maintaining direct compatibility with existing signal conditioning and amplification circuits.

Power Supply Compatibility: The CMC-2742WBL-25L operates across a voltage range of 2 V to 10 V, which encompasses the original part's 2.5 V to 5.5 V operating window. Both devices draw 500 µA supply current, ensuring equivalent power delivery requirements.

Regulatory Compliance: Both parts maintain ROHS3 compliance, satisfying environmental and hazardous substance restrictions applicable to the original design.

Product Availability: The CMC-2742WBL-25L maintains active product status with substantial inventory availability (29,998 units), providing long-term supply security compared to the obsolete HM-31308-P113.

Performance Considerations: The substitute exhibits extended frequency response (100 Hz to 20 kHz versus 100 Hz to 10 kHz) and reduced sensitivity (-42dB versus -32dB), which may require signal chain recalibration. The impedance increase from 500 Ohms to 2.2 kOhms necessitates verification of input stage compatibility with existing preamplifier designs.

Frequently Asked Questions (FAQ)

Q: Can the CMC-2742WBL-25L be directly substituted without circuit modifications?

A: Direct mechanical and electrical substitution is possible due to matching form factor and wire lead termination. However, the impedance difference (500 Ohms to 2.2 kOhms) and sensitivity change (-32dB to -42dB) may require input stage recalibration to maintain equivalent signal levels and frequency response characteristics.

Q: What is the impact of the height difference between the two microphones?

A: The CMC-2742WBL-25L is 0.019" (0.50mm) taller than the HM-31308-P113. This dimension must be verified against enclosure clearances and PCB layout constraints to ensure mechanical fit within the target application.

Q: Are both microphones suitable for the same voltage supply?

A: The CMC-2742WBL-25L voltage range (2 V to 10 V) encompasses the original part's operating window (2.5 V to 5.5 V). Both devices operate at 500 µA supply current, ensuring equivalent power delivery requirements.

Q: How does the extended frequency response of the substitute affect application compatibility?

A: The CMC-2742WBL-25L extends frequency response to 20 kHz compared to the original 10 kHz upper limit. This extended bandwidth may introduce additional high-frequency content into the signal chain. Applications requiring specific frequency response characteristics must evaluate whether this extension affects performance or introduces unwanted noise.

Q: What compliance certifications apply to both microphones?

A: Both the HM-31308-P113 and CMC-2742WBL-25L maintain ROHS3 compliance, satisfying hazardous substance restrictions. Both devices carry EAR99 export classification and equivalent HTSUS commodity codes.

Q: Is the omnidirectional characteristic of the substitute a significant difference?

A: The CMC-2742WBL-25L is specified as omnidirectional, whereas the original part does not specify directional characteristics. Omnidirectional response may affect acoustic performance in applications requiring directional sensitivity or noise rejection.