RN42N-I/RMCOS477 Equivalent & Substitute Parts

Part Overview

The RN42N-I/RMCOS477 is a Bluetooth v2.1 + EDR Class 2 transceiver module manufactured by Microchip Technology, designed for 2.4GHz RF applications requiring short-range wireless connectivity. This surface mount module operates across a supply voltage range of 3V to 3.6V and delivers a maximum output power of 4dBm with receiver sensitivity of -86dBm. The module features SPI and UART serial interfaces and operates across an extended temperature range of -40°C to 85°C.

The RN42N-I/RMCOS477 has reached obsolete product status. Identifying equivalent and substitute components is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications currently utilizing this module.

Substiute Parts

RN42N-I/RMCOS477

Microchip TechnologyIn Stock: 1062RN42N-I/RMCOS477 Datasheet

Current PartRFQ

RN4678-V/RM122

Microchip TechnologyIn Stock: 1149RN4678-V/RM122 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the RN42N-I/RMCOS477 is evaluated based on the following critical parameters that determine functional compatibility:

RF Standard and Protocol Compatibility: Both the main part and substitute must operate within the 2.4GHz ISM band and support Bluetooth wireless communication standards. The RN42N-I/RMCOS477 operates under Bluetooth v2.1 + EDR Class 2 specification.

Physical Form Factor: Surface mount packaging is required to maintain PCB integration compatibility. The main part utilizes a 35-SMD Module package.

Serial Communication Interfaces: The module must provide serial interface capability for host microcontroller communication. The RN42N-I/RMCOS477 supports both SPI and UART interfaces.

Electrical Operating Parameters: Supply voltage range, output power, and receiver sensitivity define the electrical performance envelope. The main part operates at 3V to 3.6V supply with 4dBm output power and -86dBm sensitivity.

Temperature Operating Range: The module must function across the specified temperature extremes. The RN42N-I/RMCOS477 operates from -40°C to 85°C.

The RN4678-V/RM122 is identified as a manufacturer-recommended substitute based on shared RF standard (Bluetooth), frequency band (2.4GHz), surface mount form factor, and serial interface capability (UART).

Parameter Comparison

Engineering Selection Recommendations

Product Status Consideration: The RN42N-I/RMCOS477 is classified as obsolete, indicating discontinued manufacturing and limited availability. The RN4678-V/RM122 maintains active product status with confirmed inventory availability (1134 Pcs New Original In Stock), supporting long-term supply chain requirements.

Compliance and Certification: The RN4678-V/RM122 carries RoHS3 compliance certification and REACH unaffected status, meeting current regulatory requirements for electronic component manufacturing and distribution. The substitute part is assigned ECCN 5A992C and HTSUS 8529.90.2100 classifications.

Manufacturer Support: Both components are manufactured by Microchip Technology, ensuring consistent design philosophy, documentation standards, and technical support continuity.

Functional Capability: The RN4678-V/RM122 operates under Bluetooth v5.0 protocol, representing a newer standard generation compared to the v2.1 + EDR specification of the main part. The substitute provides improved receiver sensitivity (-92dBm versus -86dBm) and integrated antenna functionality, eliminating the requirement for external antenna components.

Interface Compatibility: The substitute part provides UART serial interface, which is present in the main part specification. The main part additionally supports SPI interface; applications requiring SPI communication must evaluate alternative solutions or implement protocol conversion.

Electrical Operating Range: The RN4678-V/RM122 supply voltage range (3.3V to 4.2V) overlaps with the main part range (3V to 3.6V) at 3.3V to 3.6V. Applications operating at the lower boundary (3V) require design verification. The substitute exhibits lower output power (1.5dBm versus 4dBm), which may impact link budget calculations in range-limited applications.

Temperature Operating Range: The substitute operates across -20°C to 70°C, which is narrower than the main part range of -40°C to 85°C. Applications requiring operation below -20°C or above 70°C cannot use this substitute without thermal management modifications.

Frequently Asked Questions (FAQ)

Q: Can the RN4678-V/RM122 directly replace the RN42N-I/RMCOS477 in existing designs?

A: Direct replacement requires design verification across multiple parameters. The substitute operates under Bluetooth v5.0 protocol versus v2.1 + EDR, features different package dimensions (33-SMD versus 35-SMD), and provides UART interface only (SPI not available). Supply voltage overlap exists at 3.3V to 3.6V. Applications operating at 3V supply voltage or requiring SPI communication require design modifications.

Q: What are the key differences in RF performance between these modules?

A: The RN4678-V/RM122 provides superior receiver sensitivity (-92dBm versus -86dBm), enabling detection of weaker incoming signals. However, the substitute delivers lower transmit power (1.5dBm versus 4dBm), reducing maximum transmission range. The main part supports 3Mbps data rate; the substitute operates at 1Mbps. Applications with specific range or data rate requirements must evaluate these performance differences.

Q: How does the antenna configuration differ between these parts?

A: The RN42N-I/RMCOS477 requires an external antenna (Antenna Not Included), necessitating PCB antenna design or discrete antenna component integration. The RN4678-V/RM122 features an integrated chip antenna, eliminating external antenna requirements and reducing PCB design complexity.

Q: Are there temperature range limitations with the substitute part?

A: The RN4678-V/RM122 operates across -20°C to 70°C ambient temperature, compared to the main part range of -40°C to 85°C. Applications requiring operation below -20°C or above 70°C cannot use this substitute without implementing external thermal management or selecting alternative components.

Q: What serial interface options are available with the substitute?

A: The RN4678-V/RM122 provides UART serial interface only. The main part supports both SPI and UART. Applications currently utilizing SPI communication must implement protocol conversion or select alternative substitute components that support SPI interface.

Q: Does the substitute part require firmware or software modifications?

A: The RN4678-V/RM122 operates under Bluetooth v5.0 protocol, whereas the main part implements Bluetooth v2.1 + EDR. Protocol differences may require host microcontroller firmware updates to support v5.0 features and command structures. Compatibility verification with existing application firmware is necessary.

Q: What is the supply voltage compatibility between these modules?

A: The RN42N-I/RMCOS477 operates at 3V to 3.6V; the RN4678-V/RM122 operates at 3.3V to 4.2V. Overlapping operation occurs at 3.3V to 3.6V. Designs operating at 3V supply voltage require voltage regulation or alternative component selection to use the substitute part.

Q: Are there package footprint differences that affect PCB layout?

A: The main part uses a 35-SMD Module package; the substitute uses a 33-SMD Module package. Physical dimensions and pin configurations differ, requiring PCB layout modifications and potential revalidation of assembly processes.