WM7121PIMSE/RV Equivalent & Substitute Parts

Part Overview

The WM7121PIMSE/RV is an analog MEMS microphone manufactured by Cirrus Logic Inc., designed for omnidirectional audio capture across the 62 Hz to 13 kHz frequency range. This component operates within a 1.5 V to 3.7 V supply range and delivers -38dB sensitivity at 94dB SPL with a 65dB signal-to-noise ratio. The device features top-mounted solder pad termination in a compact 3.76mm × 2.95mm rectangular package.

The WM7121PIMSE/RV is classified as obsolete. Identifying equivalent substitute parts is necessary to maintain design continuity, ensure supply chain reliability, and support ongoing production requirements for applications utilizing this microphone architecture.

Key Parameters

Parameter	WM7121PIMSE/RV
Manufacturer	Cirrus Logic Inc.
Product Status	Obsolete
Type	MEMS (Silicon)
Output Type	Analog
Direction	Omnidirectional
Frequency Range	62 Hz ~ 13 kHz
Sensitivity	-38dB ±1dB @ 94dB SPL
S/N Ratio	65dB
Impedance	55 Ohms
Voltage Range	1.5 V ~ 3.7 V
Current - Supply	240 µA
Port Location	Top
Termination	Solder Pads
Size / Dimension	0.148" L x 0.116" W (3.76mm x 2.95mm)
Height (Max)	0.047" (1.20mm)
Shape	Rectangular
Moisture Sensitivity Level (MSL)	2A (4 Weeks)

Substitute Part Grouping Explanation

Substitute parts for the WM7121PIMSE/RV are identified based on the following critical parameters that determine functional and mechanical compatibility:

Electrical Compatibility Criteria:

Output type: Analog
Direction: Omnidirectional
Termination: Solder Pads
Port location: Top
Voltage range overlap with 1.5 V ~ 3.7 V supply
MEMS silicon microphone architecture

Mechanical Compatibility Criteria:

Package dimensions: 3.76mm × 2.95mm (0.148" L x 0.116" W)
Height: 0.047" (1.20mm) maximum
Rectangular shape
Solder pad termination

The SPU0410HR5H-PB from Knowles meets these substitution criteria through identical mechanical packaging, compatible voltage operation, and equivalent analog omnidirectional MEMS architecture.

Parameter Comparison

Parameter	WM7121PIMSE/RV (Cirrus Logic)	SPU0410HR5H-PB (Knowles)
Type	MEMS (Silicon)	MEMS (Silicon)
Output Type	Analog	Analog
Direction	Omnidirectional	Omnidirectional
Frequency Range	62 Hz ~ 13 kHz	100 Hz ~ 10 kHz
Sensitivity	-38dB ±1dB @ 94dB SPL	-42dB ±3dB @ 94dB SPL
S/N Ratio	65dB	59dB
Impedance	55 Ohms	400 Ohms
Voltage Range	1.5 V ~ 3.7 V	1.5 V ~ 3.6 V
Current - Supply	240 µA	160 µA
Port Location	Top	Top
Termination	Solder Pads	Solder Pads
Size / Dimension	3.76mm x 2.95mm	3.76mm x 2.95mm
Height (Max)	0.047" (1.20mm)	0.047" (1.20mm)
Shape	Rectangular	Rectangular
Product Status	Obsolete	Active
Moisture Sensitivity Level (MSL)	2A (4 Weeks)	1 (Unlimited)

Engineering Selection Recommendations

The SPU0410HR5H-PB represents the primary substitute for the obsolete WM7121PIMSE/RV based on the following engineering factors:

Product Status & Supply Continuity: The SPU0410HR5H-PB maintains active product status with confirmed inventory availability (15,837 pcs), ensuring reliable supply for ongoing production and design transitions from the obsolete WM7121PIMSE/RV.

Mechanical Compatibility: Both components share identical package dimensions (3.76mm × 2.95mm) and height specifications (0.047" maximum), enabling direct PCB layout compatibility without redesign requirements.

Electrical Architecture: Both devices employ analog MEMS silicon microphone technology with omnidirectional pickup patterns and top-mounted solder pad termination, maintaining functional equivalence in audio signal acquisition.

Voltage Operation: The SPU0410HR5H-PB operates within 1.5 V to 3.6 V, overlapping the WM7121PIMSE/RV supply range of 1.5 V to 3.7 V, permitting operation across standard supply configurations.

Compliance & Certifications: The SPU0410HR5H-PB is ROHS3 compliant with MSL 1 rating (unlimited moisture exposure), providing improved handling and storage characteristics compared to the WM7121PIMSE/RV MSL 2A specification.

Frequently Asked Questions (FAQ)

Q: Can the SPU0410HR5H-PB directly replace the WM7121PIMSE/RV without PCB modifications?

A: Yes. Both components feature identical mechanical packaging (3.76mm × 2.95mm × 1.20mm height) with solder pad termination at the top port location. Direct PCB footprint compatibility is maintained.

Q: What are the key electrical differences between these microphones?

A: The SPU0410HR5H-PB exhibits lower impedance (400 Ohms vs. 55 Ohms), reduced supply current (160 µA vs. 240 µA), and a narrower frequency range (100 Hz ~ 10 kHz vs. 62 Hz ~ 13 kHz). Sensitivity differs by 4dB (-42dB vs. -38dB), and S/N ratio is 6dB lower (59dB vs. 65dB). Circuit impedance matching and signal conditioning may require adjustment.

Q: Are there handling or storage differences between these parts?

A: Yes. The SPU0410HR5H-PB carries MSL 1 rating (unlimited moisture exposure), while the WM7121PIMSE/RV is MSL 2A (4-week limit). The substitute part permits extended storage without desiccant requirements and offers greater handling flexibility.

Q: What compliance certifications apply to the SPU0410HR5H-PB?

A: The SPU0410HR5H-PB is ROHS3 compliant. Both components carry EAR99 ECCN classification and 8518.10.8030 HTSUS code.

Q: Is the frequency response difference significant for audio applications?

A: The WM7121PIMSE/RV extends to 62 Hz and 13 kHz, while the SPU0410HR5H-PB operates from 100 Hz to 10 kHz. Applications requiring sub-100 Hz or above 10 kHz response must evaluate whether the narrower bandwidth of the substitute part meets system requirements.

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