FD4000121 Equivalent & Substitute Parts

Part Overview

The FD4000121 is a 40 MHz crystal oscillator manufactured by Diodes Incorporated, designed for applications requiring a standard XO (Standard) CMOS output with Enable/Disable functionality. This Surface Mount Device (SMD) operates at 3.3V supply voltage and is housed in a compact 4-SMD, No Lead package measuring 5.00mm x 3.20mm. The part is currently Active in product status with 1045 units in stock.

Substitute parts become necessary when the primary part experiences supply constraints, discontinuation, or when design flexibility requires alternative qualified sources. The parts listed below maintain electrical and mechanical compatibility within the specified parameter tolerances.

Key Parameters

Parameter	Value
Frequency	40 MHz
Output Type	CMOS
Supply Voltage	3.3V
Function	Enable/Disable
Frequency Stability	±50ppm
Operating Temperature Range	-40°C ~ 85°C
Package Type	4-SMD, No Lead
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the FD4000121 is determined by strict alignment with the following core parameters:

Frequency: 40 MHz (exact match required)
Output: CMOS (exact match required)
Supply Voltage: 3.3V (exact match required)
Function: Enable/Disable (exact match required)
Frequency Stability: ±50ppm (exact match required)
Operating Temperature: -40°C ~ 85°C (exact match required)
Package: 4-SMD, No Lead (exact match required)
Mounting: Surface Mount (exact match required)

All substitute parts listed below meet these criteria. Variations in secondary parameters such as maximum supply current, physical dimensions within tolerance, and product status do not affect functional substitutability for this oscillator category.

Parameter Comparison

Parameter	FD4000121 (Diodes)	LFSPXO026068BULK (IQD)	SXO53C3A481-40.000M (Suntsu)
Manufacturer	Diodes Incorporated	IQD Frequency Products	Suntsu Electronics, Inc.
Frequency	40 MHz	40 MHz	40 MHz
Output Type	CMOS	CMOS	CMOS
Supply Voltage	3.3V	3.3V	3.3V
Function	Enable/Disable	Enable/Disable	Enable/Disable
Frequency Stability	±50ppm	±50ppm	±50ppm
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Package / Case	4-SMD, No Lead	4-SMD, No Lead	4-SMD, No Lead
Mounting Type	Surface Mount	Surface Mount	Surface Mount
Current - Supply (Max)	15mA	20mA	25mA
Size / Dimension	5.00mm x 3.20mm	5.20mm x 3.40mm	5.00mm x 3.20mm
Height - Seated (Max)	1.30mm	1.30mm	1.40mm
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Active	Discontinued at DiGi Electronics	Active

Engineering Selection Recommendations

FD4000121 (Diodes Incorporated) — Primary selection for new designs. Active product status ensures long-term availability and supply continuity. ROHS3 compliant with Moisture Sensitivity Level 1 (Unlimited), indicating robust handling characteristics. Current supply requirement of 15mA is the lowest among the three options, making it optimal for power-constrained applications.

LFSPXO026068BULK (IQD Frequency Products) — Suitable for existing designs requiring component replacement. Discontinued at DiGi Electronics status indicates limited future availability; use only when existing inventory is available or when design lock-in to this part number is required. ROHS3 compliant. Maximum supply current of 20mA is moderate. Physical dimensions (5.20mm x 3.40mm) are slightly larger than the primary part; verify PCB layout compatibility before substitution.

SXO53C3A481-40.000M (Suntsu Electronics, Inc.) — Active product with highest inventory availability (1951 units). Suitable for new designs or high-volume production requiring assured supply. ROHS3 compliant. Maximum supply current of 25mA is the highest; confirm power budget compatibility in applications with tight current constraints. Height dimension (1.40mm) exceeds the primary part by 0.10mm; verify clearance in space-constrained assemblies.

Frequently Asked Questions (FAQ)

Q: Can I substitute FD4000121 with LFSPXO026068BULK in an existing design?

A: Yes, electrical substitution is valid. Both parts share identical frequency (40 MHz), output type (CMOS), supply voltage (3.3V), function (Enable/Disable), frequency stability (±50ppm), and operating temperature range (-40°C ~ 85°C). Physical dimensions differ slightly (5.20mm x 3.40mm vs. 5.00mm x 3.20mm); verify PCB footprint and layout clearances before implementation.

Q: What is the primary difference between these three oscillators?

A: All three parts are functionally equivalent for the specified 40 MHz CMOS oscillator application. Differences exist in maximum supply current (15mA, 20mA, and 25mA respectively), physical dimensions, and product availability status. Selection depends on power budget, PCB space constraints, and supply chain requirements.

Q: Is the SXO53C3A481-40.000M suitable for space-constrained applications?

A: The SXO53C3A481-40.000M has a seated height of 1.40mm, which is 0.10mm taller than the FD4000121 (1.30mm). For applications with strict height limitations, verify clearance above the component before selection. Horizontal dimensions (5.00mm x 3.20mm) match the primary part.

Q: Are all three parts RoHS compliant?

A: Yes, all three parts are ROHS3 compliant and suitable for applications requiring RoHS certification. REACH status is Unaffected for all parts.

Q: Which part should I select for a new design?

A: FD4000121 is recommended for new designs due to Active product status, ensuring long-term availability and supply stability. SXO53C3A481-40.000M is an alternative with higher inventory levels if supply assurance is critical.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message