RF Switch IC SPDT 42551-51 Equivalent & Substitute Parts

Part Overview

The 42551-51 is an RF Switch IC with Single-Pole Double-Throw (SPDT) topology manufactured by pSemi under the UltraCMOS® series. This component operates across a frequency range of 9 kHz to 6 GHz with 50 Ohm impedance and is housed in a 20-QFN (4x4) surface mount package. The part is currently classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system support and new design implementations.

Substiute Parts

42551-51

pSemiIn Stock: 92042551-51 Datasheet

Current PartRFQ

PE42553B-Z

pSemiIn Stock: 26780PE42553B-Z Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

The PE42553B-Z qualifies as a functional substitute for the 42551-51 based on the following substitution criteria:

Core Compatibility Parameters:

• Circuit topology: Both are SPDT RF switches
• Impedance: Both operate at 50 Ohm
• Mounting type: Both are surface mount components
• Operating temperature range: Both support -40°C ~ 85°C
• Manufacturer: Both are pSemi products

Performance Considerations: The PE42553B-Z extends the frequency range to 8 GHz (versus 6 GHz for the 42551-51), providing broader operational capability. The substitute demonstrates improved isolation (45 dB versus 21 dB) and lower insertion loss (0.85 dB versus 0.95 dB). The PE42553B-Z supports a wider supply voltage range (2.3 V ~ 5.5 V) compared to the 42551-51 (2.5 V ~ 3 V), offering greater design flexibility.

Package Difference: The PE42553B-Z uses a 16-QFN (3x3) package versus the 20-QFN (4x4) package of the 42551-51. This represents a physical footprint reduction and requires PCB layout modification.

Parameter Comparison

Engineering Selection Recommendations

The PE42553B-Z is an active product with current manufacturing support, whereas the 42551-51 is obsolete. For new designs or system refreshes, the PE42553B-Z is the appropriate selection. The substitute meets or exceeds the electrical performance of the original part across isolation and linearity metrics.

The PE42553B-Z carries ROHS3 compliance and REACH unaffected status, supporting modern regulatory requirements. The original 42551-51 compliance certifications are not fully specified in available documentation.

PCB layout modification is required due to package footprint change from 20-QFN (4x4) to 16-QFN (3x3). Supply voltage design margins must accommodate the PE42553B-Z's wider operating range (2.3 V ~ 5.5 V) if the original design operated at the lower end of the 42551-51 specification (2.5 V ~ 3 V).

Frequently Asked Questions (FAQ)

Q: Can PE42553B-Z directly replace 42551-51 without PCB modification?

A: No. The PE42553B-Z uses a 16-QFN (3x3) package while the 42551-51 uses a 20-QFN (4x4) package. PCB footprint redesign is required.

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

A: The PE42553B-Z provides superior isolation (45 dB versus 21 dB), lower insertion loss (0.85 dB versus 0.95 dB), and higher third-order intercept point (66 dBm versus 50 dBm). The PE42553B-Z also extends frequency coverage to 8 GHz compared to 6 GHz for the 42551-51.

Q: Is the PE42553B-Z suitable for applications originally designed for the 42551-51?

A: Yes, provided that PCB layout is modified to accommodate the different package footprint and that supply voltage design supports the PE42553B-Z operating range. The improved performance characteristics of the PE42553B-Z make it suitable for the same application classes.

Q: What is the moisture sensitivity difference between these parts?

A: The 42551-51 is MSL 1 (unlimited moisture exposure tolerance), while the PE42553B-Z is MSL 3 (168-hour moisture exposure limit). The PE42553B-Z requires standard moisture control during storage and handling per IPC-A-610 guidelines.

Q: Are both parts available in the same packaging format?

A: No. The 42551-51 is available in tape and reel format as standard. The PE42553B-Z is specified as tape and reel (TR) packaging. Confirm packaging availability with your supplier for your specific procurement requirements.