40 MHz ±10ppm Crystal 10pF SMD - TXC 7M40000049 Equivalent & Substitute Parts

Part Overview

The TXC 7M40000049 is a 40 MHz fundamental mode crystal oscillator in 4-SMD surface mount package with 10pF load capacitance and ±10ppm frequency stability. This component is classified as Active product status with full RoHS3 compliance and unlimited moisture sensitivity rating (MSL 1). Substitute parts are identified based on matching core electrical parameters: 40 MHz frequency, ±10ppm stability, 4-SMD no-lead package, and -30°C to 85°C operating temperature range. Load capacitance variations and ESR differences define substitution boundaries for circuit compatibility.

Key Parameters

Parameter	Value	Unit	Substitution Relevance
Frequency	40.0000	MHz	Critical - Must match exactly
Frequency Stability	±10	ppm	Critical - Must match or better
Load Capacitance	10	pF	Critical - Affects circuit tuning
Operating Temperature Range	-30 to 85	°C	Critical - Must cover application range
Mounting Type	Surface Mount	-	Critical - PCB assembly compatibility
Package / Case	4-SMD, No Lead	-	Critical - Physical footprint match
RoHS Status	RoHS Compliant	-	Regulatory - Environmental compliance
MSL Rating	1 (Unlimited)	-	Handling - Storage and assembly conditions

Substitute Part Grouping Explanation

Substitution logic is based on strict parameter matching within the following categories:

Primary Substitution Criteria (Non-negotiable):

Frequency: 40 MHz (exact match required)
Frequency Stability: ±10ppm (exact match required)
Operating Temperature: -30°C to 85°C (exact match required)
Package: 4-SMD, No Lead (exact match required)
Mounting: Surface Mount (exact match required)

Secondary Substitution Parameters (Application-dependent):

Load Capacitance: 10pF (primary specification); 9pF, 8pF, 7pF variants acceptable only if circuit design permits load capacitance tolerance
ESR (Equivalent Series Resistance): 30Ω to 50Ω range; affects circuit startup and frequency accuracy
Physical Dimensions: Variations in length, width, and height permitted within PCB layout constraints

Compliance Parameters (Mandatory for regulated applications):

RoHS Status: ROHS3 Compliant (all substitutes meet this requirement)
MSL Rating: 1 (Unlimited) - all substitutes match
REACH Status: REACH Unaffected (all substitutes match)

Substitute parts are grouped into two categories: Direct Load Capacitance Matches (10pF) and Alternative Load Capacitance Variants (7pF, 8pF, 9pF). The latter group requires circuit validation to confirm load capacitance tolerance.

Parameter Comparison

Manufacturer	Part Number	Frequency (MHz)	Stability (ppm)	Load Cap (pF)	ESR (Ω)	Temp Range (°C)	Package	Size (mm)	Height Max (mm)	RoHS Status	Inventory (Pcs)
TXC CORPORATION	7M40000049	40.0000	±10	10	-	-30 to 85	4-SMD, No Lead	3.20 x 2.50	0.80	RoHS Compliant	18100
ECS Inc.	ECS-400-10-36-CKY-TR	40.0000	±10	10	40	-30 to 85	4-SMD, No Lead	2.50 x 2.00	0.60	ROHS3 Compliant	5575
ECS Inc.	ECS-400-10-36B-CKY-TR	40.0000	±10	10	30	-30 to 85	4-SMD, No Lead	2.50 x 2.00	0.65	ROHS3 Compliant	2786
ECS Inc.	ECS-400-10-37B-CKY-TR	40.0000	±10	10	40	-30 to 85	4-SMD, No Lead	2.00 x 1.60	0.50	ROHS3 Compliant	1913
ECS Inc.	ECS-400-9-36B-CKY-TR	40.0000	±10	9	30	-30 to 85	4-SMD, No Lead	2.50 x 2.00	0.65	ROHS3 Compliant	1435
Diodes Incorporated	FH4000074Z	40.0000	±10	8	30	-30 to 85	4-SMD, No Lead	2.50 x 2.00	0.70	ROHS3 Compliant	821
Diodes Incorporated	FL400WFQA1	40.0000	±10	7	40	-30 to 85	4-SMD, No Lead	3.20 x 2.50	0.78	ROHS3 Compliant	962
Diodes Incorporated	FW400WFQA1	40.0000	±10	7	40	-30 to 85	4-SMD, No Lead	2.00 x 1.60	0.55	ROHS3 Compliant	3452
Murata Electronics	XRCGB40M000F1S1BR0	40.0000	±10	8	50	-30 to 85	4-SMD, No Lead	2.00 x 1.60	0.70	ROHS3 Compliant	6900

Engineering Selection Recommendations

Direct Substitutes (10pF Load Capacitance - No Circuit Modification Required):

ECS-400-10-36-CKY-TR (ECS Inc., ECX-2236 Series): Identical electrical specifications with 40Ω ESR. Smaller footprint (2.50 x 2.00mm) and lower profile (0.60mm) suitable for space-constrained layouts. ROHS3 compliant. Inventory: 5575 units.
ECS-400-10-36B-CKY-TR (ECS Inc., ECX-2236B Series): Identical electrical specifications with 30Ω ESR (lower impedance). Smaller footprint (2.50 x 2.00mm) and profile (0.65mm). ROHS3 compliant. Inventory: 2786 units.
ECS-400-10-37B-CKY-TR (ECS Inc., ECX-1637B Series): Identical electrical specifications with 40Ω ESR. Compact footprint (2.00 x 1.60mm) and minimal profile (0.50mm) for high-density PCB designs. ROHS3 compliant. Inventory: 1913 units.

Alternative Load Capacitance Variants (7pF, 8pF, 9pF - Circuit Validation Required):

ECS-400-9-36B-CKY-TR (ECS Inc., ECX-2236B Series): 9pF load capacitance with 30Ω ESR. Suitable for circuits designed with 9pF tolerance. Footprint 2.50 x 2.00mm. ROHS3 compliant. Inventory: 1435 units.
FH4000074Z (Diodes Incorporated, SaRonix-eCera™ FH Series): 8pF load capacitance with 30Ω ESR. Suitable for circuits designed with 8pF tolerance. Footprint 2.50 x 2.00mm. ROHS3 compliant. Inventory: 821 units.
FL400WFQA1 (Diodes Incorporated, SaRonix-eCera™ FL Series): 7pF load capacitance with 40Ω ESR. Suitable for circuits designed with 7pF tolerance. Footprint matches TXC original (3.20 x 2.50mm). ROHS3 compliant. Inventory: 962 units.
FW400WFQA1 (Diodes Incorporated, SaRonix-eCera™ FW Series): 7pF load capacitance with 40Ω ESR. Compact footprint (2.00 x 1.60mm) and minimal profile (0.55mm). ROHS3 compliant. Inventory: 3452 units.
XRCGB40M000F1S1BR0 (Murata Electronics, XRCGB Series): 8pF load capacitance with 50Ω ESR (highest impedance). Compact footprint (2.00 x 1.60mm). ROHS3 compliant. Inventory: 6900 units.

Selection Criteria:

Footprint Priority: ECS-400-10-37B-CKY-TR, FW400WFQA1, or XRCGB40M000F1S1BR0 for space-constrained designs
ESR Consideration: Lower ESR (30Ω) variants for low-power circuits; higher ESR (40-50Ω) for standard applications
Inventory Availability: XRCGB40M000F1S1BR0 (6900 units) or FW400WFQA1 (3452 units) for high-volume procurement
Load Capacitance Match: ECS-400-10-36-CKY-TR, ECS-400-10-36B-CKY-TR, or ECS-400-10-37B-CKY-TR for direct replacement without circuit modification

All substitute parts maintain Active product status, ROHS3 compliance, MSL 1 rating, and -30°C to 85°C operating temperature range.

Frequently Asked Questions (FAQ)

Q1: Can I use a 9pF or 8pF load capacitance crystal as a direct replacement for the 10pF TXC 7M40000049?

A: Load capacitance directly affects crystal oscillator frequency tuning. Substitution with different load capacitance values (9pF, 8pF, 7pF) requires circuit validation. The oscillator circuit must be designed to accommodate the alternative load capacitance specification. Consult circuit design documentation and perform frequency accuracy testing before deployment.

Q2: What is the significance of ESR (Equivalent Series Resistance) in crystal selection?

A: ESR affects crystal startup behavior, frequency stability, and power consumption. The TXC 7M40000049 does not specify ESR. Substitute parts range from 30Ω to 50Ω. Lower ESR (30Ω) reduces startup time and power draw; higher ESR (40-50Ω) provides better noise immunity. Select based on circuit design requirements and oscillator IC specifications.

Q3: Are all substitute parts physically compatible with the TXC 7M40000049 PCB footprint?

A: No. Physical dimensions vary significantly. The TXC original measures 3.20 x 2.50mm. ECS-400-10-36-CKY-TR and ECS-400-10-36B-CKY-TR measure 2.50 x 2.00mm. ECS-400-10-37B-CKY-TR, FW400WFQA1, and XRCGB40M000F1S1BR0 measure 2.00 x 1.60mm. Verify PCB footprint compatibility before selection. Smaller packages may require PCB layout modification.

Q4: Do all substitute parts meet the same compliance requirements as the TXC 7M40000049?

A: Yes. All listed substitute parts are ROHS3 compliant, REACH unaffected, MSL 1 rated, and classified as Active product status. All share identical ECCN (EAR99) and HTSUS (8541.60.0060) classifications. Compliance documentation is equivalent across all options.

Q5: Which substitute part offers the best inventory availability?

A: XRCGB40M000F1S1BR0 (Murata Electronics) has the highest inventory at 6900 units. FW400WFQA1 (Diodes Incorporated) offers 3452 units. For direct 10pF load capacitance match, ECS-400-10-36-CKY-TR provides 5575 units. Inventory levels support high-volume procurement requirements.

Q6: What is the difference between ECS-400-10-36-CKY-TR and ECS-400-10-36B-CKY-TR?

A: Both are 40 MHz ±10ppm crystals with 10pF load capacitance and 4-SMD package. The primary difference is ESR: ECS-400-10-36-CKY-TR has 40Ω ESR (ECX-2236 series), while ECS-400-10-36B-CKY-TR has 30Ω ESR (ECX-2236B series). The "B" variant offers lower impedance and faster startup characteristics. Height differs slightly: 0.60mm vs. 0.65mm.

Q7: Can I substitute FW400WFQA1 (7pF) for the 10pF TXC crystal without circuit modification?

A: No. The 3pF load capacitance difference significantly affects oscillator frequency tuning. FW400WFQA1 is suitable only for circuits specifically designed for 7pF load capacitance. Frequency accuracy cannot be guaranteed without circuit validation and potential tuning adjustments.

Q8: What is the height difference between substitute parts, and does it matter?

A: Height varies from 0.50mm (ECS-400-10-37B-CKY-TR) to 0.80mm (TXC 7M40000049). Height differences affect PCB assembly clearance and component stacking. Verify clearance requirements for your application, particularly in space-constrained designs or multi-layer PCB assemblies.

Q9: Are Diodes Incorporated and Murata Electronics crystals interchangeable with ECS Inc. parts?

A: Interchangeability depends on matching electrical specifications (frequency, stability, load capacitance, ESR) and physical footprint. All three manufacturers produce 40 MHz ±10ppm crystals in 4-SMD packages, but load capacitance and ESR vary. Direct substitution is possible only when all electrical parameters match the circuit design requirements.

Q10: Which substitute part is recommended for new designs?

A: For new designs, ECS-400-10-36B-CKY-TR or ECS-400-10-37B-CKY-TR offer optimal balance of electrical performance (30Ω ESR for reliable startup), compact footprint, and adequate inventory. For space-critical applications, FW400WFQA1 or XRCGB40M000F1S1BR0 provide minimal profile (0.55mm and 0.70mm respectively). Confirm load capacitance compatibility with oscillator IC specifications before final selection.

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