RN42-I/RM Equivalent & Substitute Parts

Part Overview

The RN42-I/RM is a Bluetooth v2.1 +EDR Class 2 transceiver module manufactured by Microchip Technology, designed for 2.4GHz RF applications with integrated trace antenna and surface mount packaging. This module is classified as obsolete, making identification of suitable substitute components essential for ongoing system support, redesigns, and production continuity. The RN42-I/RM provides UART serial interface connectivity with 4dBm output power and -80dBm sensitivity across the -40°C to 85°C operating temperature range.

Substiute Parts

RN42-I/RM

Microchip TechnologyIn Stock: 1000300RN42-I/RM Datasheet

Current PartRFQ

RN42-I/RM630

Microchip TechnologyIn Stock: 1000487RN42-I/RM630 Datasheet

DirectRFQ

RN4678-V/RM122

Microchip TechnologyIn Stock: 1149RN4678-V/RM122 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the RN42-I/RM is determined by the following critical parameters:

Primary Compatibility Criteria:

• Manufacturer: Microchip Technology (same manufacturer ensures firmware and protocol compatibility)
• RF Family/Standard: Bluetooth (maintains RF domain consistency)
• Frequency: 2.4GHz (preserves frequency band operation)
• Mounting Type: Surface Mount (ensures PCB assembly compatibility)
• RoHS Status: ROHS3 Compliant (maintains regulatory compliance)

Secondary Compatibility Considerations:

• Serial Interfaces: UART minimum requirement (RN42-I/RM uses UART; substitutes may offer additional interfaces)
• Voltage Supply Range: Must accommodate 3V ~ 3.6V operation or provide compatible supply voltage
• Operating Temperature Range: Must support -40°C ~ 85°C or equivalent industrial range
• Package/Case: Surface mount module form factor

Two substitute parts are identified:

1. RN42-I/RM630 — Direct manufacturer variant with enhanced data rate (3Mbps vs 300kbps), expanded serial interfaces (SPI, UART, USB), and increased current consumption. Maintains Bluetooth v2.1 +EDR Class 2 protocol and identical voltage/temperature specifications.

2. RN4678-V/RM122 — Manufacturer-recommended upgrade featuring Bluetooth v5.0 protocol, improved sensitivity (-92dBm vs -80dBm), integrated IC (IS1678SM), and expanded memory (4MB Flash, 320kB ROM, 28kB SRAM). Represents a technology advancement with different voltage range (3.3V ~ 4.2V) and narrower operating temperature (-20°C ~ 70°C).

Parameter Comparison

Engineering Selection Recommendations

RN42-I/RM630 Selection Criteria: This variant is suitable for applications requiring protocol-level compatibility with the original RN42-I/RM while benefiting from enhanced data rate capability (3Mbps vs 300kbps) and expanded serial interface options (SPI, UART, USB). Both parts maintain identical voltage supply ranges (3V ~ 3.6V) and operating temperature specifications (-40°C ~ 85°C), enabling direct substitution in existing designs with minimal firmware modification. However, increased current consumption (45mA transmitting vs 30mA) must be verified against power budget constraints. Both parts carry obsolete product status and ROHS3 compliance.

RN4678-V/RM122 Selection Criteria: This manufacturer-recommended part represents a technology upgrade path for new designs or redesigns where Bluetooth v5.0 protocol support is acceptable. The RN4678-V/RM122 offers superior sensitivity (-92dBm vs -80dBm), integrated memory resources (4MB Flash, 320kB ROM, 28kB SRAM), and active product status, ensuring long-term availability and support. Critical design considerations include voltage supply range adjustment (3.3V ~ 4.2V vs 3V ~ 3.6V), reduced operating temperature range (-20°C ~ 70°C vs -40°C ~ 85°C), and lower output power (1.5dBm vs 4dBm). The RN4678-V/RM122 carries MSL rating 1 (unlimited moisture sensitivity), providing superior handling flexibility compared to MSL 3 parts.

Frequently Asked Questions (FAQ)

Q: Can RN42-I/RM630 be used as a direct drop-in replacement for RN42-I/RM?

A: RN42-I/RM630 maintains protocol compatibility (Bluetooth v2.1 +EDR Class 2), identical voltage supply range (3V ~ 3.6V), and equivalent operating temperature range (-40°C ~ 85°C). The primary design consideration is increased transmitting current (45mA vs 30mA). Firmware compatibility should be verified with Microchip documentation, as the RN42-I/RM630 offers expanded serial interfaces (SPI, USB in addition to UART) that may require software reconfiguration.

Q: What are the key differences between RN42-I/RM630 and RN4678-V/RM122?

A: RN42-I/RM630 maintains Bluetooth v2.1 +EDR Class 2 protocol, while RN4678-V/RM122 implements Bluetooth v5.0. The RN4678-V/RM122 provides improved sensitivity (-92dBm vs -80dBm), integrated memory, and active product status. However, RN4678-V/RM122 requires voltage supply adjustment (3.3V ~ 4.2V), operates within a narrower temperature range (-20°C ~ 70°C), and delivers lower output power (1.5dBm). These differences necessitate design validation for applications requiring extended temperature operation or specific power output levels.

Q: Is RN4678-V/RM122 suitable for industrial temperature range applications?

A: RN4678-V/RM122 operates within -20°C ~ 70°C (TA), which does not meet the extended industrial range (-40°C ~ 85°C) of the original RN42-I/RM. Applications requiring full industrial temperature operation must retain RN42-I/RM or RN42-I/RM630, both rated to -40°C ~ 85°C.

Q: What packaging differences exist between these modules?

A: RN42-I/RM uses 35-SMD Module packaging, RN42-I/RM630 uses generic Module packaging, and RN4678-V/RM122 uses 33-SMD Module packaging. All three employ surface mount technology. Physical footprint verification is required before PCB redesign, particularly when transitioning between 35-SMD and 33-SMD form factors.

Q: How do moisture sensitivity levels affect component handling?

A: RN42-I/RM and RN42-I/RM630 carry MSL rating 3 (168-hour floor life), requiring controlled storage and bake-out procedures before assembly. RN4678-V/RM122 carries MSL rating 1 (unlimited floor life), eliminating moisture sensitivity constraints and reducing manufacturing process complexity.

Q: Which substitute part is recommended for new product designs?

A: RN4678-V/RM122 is the manufacturer-recommended upgrade for new designs, offering active product status, Bluetooth v5.0 protocol support, and superior sensitivity. Design validation must confirm compatibility with voltage supply requirements (3.3V ~ 4.2V) and operating temperature range (-20°C ~ 70°C). For applications requiring extended temperature operation or legacy protocol compatibility, RN42-I/RM630 provides a protocol-compatible alternative within the Bluetooth v2.1 +EDR Class 2 ecosystem.