ASCSM-38.400MHZ-LR-T Equivalent & Substitute Parts

Part Overview

The ASCSM-38.400MHZ-LR-T is a 38.4 MHz MEMS-based XO (Standard) oscillator manufactured by Abracon LLC. This component operates across a wide supply voltage range of 1.7V to 3.6V with CMOS output and Enable/Disable functionality. The oscillator is housed in a compact 4-UFBGA/CSPBGA package measuring 1.79mm × 1.25mm with a maximum seated height of 0.69mm.

The ASCSM-38.400MHZ-LR-T has reached obsolete product status. Identifying equivalent substitute parts is necessary to maintain design continuity and ensure component availability for production and maintenance applications.

Substiute Parts

ASCSM-38.400MHZ-LR-T

Abracon LLCIn Stock: 990ASCSM-38.400MHZ-LR-T Datasheet

Current PartRFQ

ASCO-38.400MHZ-L-T3

Abracon LLCIn Stock: 997ASCO-38.400MHZ-L-T3 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the ASCSM-38.400MHZ-LR-T is determined by the following critical parameters:

Mandatory Matching Parameters:

• Frequency: 38.4 MHz (exact match required)
• Output Type: CMOS
• Operating Temperature Range: -40°C ~ 85°C (minimum)
• Enable/Disable Function: Required
• RoHS3 Compliance: Required

Allowable Variation Parameters:

• Base Resonator Type: MEMS or Crystal (both acceptable for frequency generation)
• Supply Voltage: Substitute must support at least 3.3V operation; the original 1.7V ~ 3.6V range may be narrowed to 3.3V in substitutes
• Frequency Stability: Original specification ±25ppm; substitutes with ±50ppm remain functionally acceptable for most applications
• Maximum Supply Current: Original 6.5mA; substitutes with ≤6mA are acceptable
• Package Type: 4-SMD No Lead or 4-UFBGA/CSPBGA (both are compact surface-mount packages)
• Package Dimensions: Minor variations acceptable if footprint compatibility is maintained

Parameter Comparison

Engineering Selection Recommendations

The ASCO-38.400MHZ-L-T3 qualifies as a direct substitute for the obsolete ASCSM-38.400MHZ-LR-T based on the following engineering criteria:

Frequency and Functional Compatibility: Both parts operate at 38.4 MHz with CMOS output and Enable/Disable control, ensuring signal compatibility with existing circuit designs.

Temperature and Compliance: Both components maintain the -40°C ~ 85°C operating temperature range and hold ROHS3 and REACH compliance certifications, meeting regulatory requirements for current manufacturing standards.

Supply Voltage Consideration: The substitute operates at a fixed 3.3V supply, compared to the original's 1.7V ~ 3.6V range. This is acceptable for applications designed around 3.3V logic levels. Designs requiring operation below 3.3V will require alternative evaluation.

Frequency Stability Trade-off: The substitute exhibits ±50ppm stability versus the original's ±25ppm. This represents a 2× relaxation in tolerance. Applications with stringent frequency accuracy requirements should evaluate impact on system performance.

Package and Footprint: The substitute uses a 4-SMD No Lead package versus the original 4-UFBGA/CSPBGA. Both are compact surface-mount packages with nearly identical dimensions (1.60mm × 1.20mm vs. 1.79mm × 1.25mm) and seated heights (0.70mm vs. 0.69mm). PCB layout modifications may be minimal, though package-specific design rules must be verified.

Active Product Status: The ASCO-38.400MHZ-L-T3 maintains active product status with confirmed inventory availability, ensuring long-term supply chain reliability.

Frequently Asked Questions (FAQ)

Q: Can the ASCO-38.400MHZ-L-T3 be used as a direct drop-in replacement for the ASCSM-38.400MHZ-LR-T?

A: The ASCO-38.400MHZ-L-T3 is functionally equivalent for 38.4 MHz CMOS oscillator applications. However, the package type differs (4-SMD No Lead vs. 4-UFBGA/CSPBGA), requiring PCB footprint verification. Supply voltage is fixed at 3.3V rather than the original's 1.7V ~ 3.6V range. Frequency stability is ±50ppm versus ±25ppm. Confirm these parameters against your circuit design requirements before implementation.

Q: What is the significance of the frequency stability difference between ±25ppm and ±50ppm?

A: Frequency stability defines the maximum deviation from the nominal 38.4 MHz frequency across operating conditions. The original part guarantees ±25ppm (±960 Hz deviation), while the substitute allows ±50ppm (±1920 Hz deviation). Applications sensitive to frequency accuracy, such as precision timing or communication protocols with tight synchronization windows, should evaluate whether the relaxed tolerance impacts system performance.

Q: Are both parts RoHS and REACH compliant?

A: Yes. Both the ASCSM-38.400MHZ-LR-T and ASCO-38.400MHZ-L-T3 are ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory standards for electronic component manufacturing and use.

Q: What are the package differences, and do they affect PCB design?

A: The original uses a 4-UFBGA/CSPBGA package (1.79mm × 1.25mm × 0.69mm), while the substitute uses a 4-SMD No Lead package (1.60mm × 1.20mm × 0.70mm). Both are ultra-compact surface-mount packages with similar footprints. PCB layout modifications are typically minimal, but design rule files (DRF) specific to each package type must be applied. Verify solder pad geometry and reflow profile compatibility with your manufacturing process.

Q: Is the supply voltage difference a concern?

A: The original operates across 1.7V ~ 3.6V, while the substitute is fixed at 3.3V. If your circuit design uses 3.3V logic levels, the substitute is fully compatible. If your design requires operation at voltages below 3.3V (such as 1.8V or 2.5V), the substitute is not suitable, and alternative parts must be evaluated.

Q: Why is the original part obsolete?

A: Product obsolescence typically results from manufacturer discontinuation decisions based on market demand, technology transitions, or product line consolidation. The ASCSM series has been superseded by the active ASCO series, which offers comparable performance with updated manufacturing processes and extended availability.

Q: What is the disable mode current specification, and why does it matter?

A: The original part specifies 15µA maximum disable mode current, while the substitute does not provide this specification. Disable mode current is relevant for low-power applications where the oscillator is periodically powered down. If your design relies on this specification, confirm the substitute's disable current performance with the manufacturer or evaluate alternative parts.