FDMS7556S N-Channel MOSFET 25V 35A/49A Equivalent & Substitute Parts

Part Overview

The FDMS7556S is an N-Channel MOSFET manufactured by onsemi, rated for 25V drain-to-source voltage with continuous drain current of 35A (Ta) or 49A (Tc). This device is part of the PowerTrench® and SyncFET™ series and is housed in an 8-PQFN (5x6) surface mount package. The FDMS7556S is classified as obsolete, making identification of equivalent and substitute parts essential for ongoing design support and production continuity. Substitute parts must maintain compatibility across critical electrical parameters including voltage rating, current handling capability, on-resistance characteristics, and thermal performance while accommodating the surface mount package format.

Substiute Parts

FDMS7556S

onsemiIn Stock: 1242FDMS7556S Datasheet

Current PartRFQ

FDMS7556S

onsemiIn Stock: 1242FDMS7556S Datasheet

Parametric EquivalentRFQ

CSD16415Q5T

Texas InstrumentsIn Stock: 16398CSD16415Q5T Datasheet

SimilarRFQ

CSD17573Q5B

Texas InstrumentsIn Stock: 17990CSD17573Q5B Datasheet

SimilarRFQ

CSD17573Q5BT

Texas InstrumentsIn Stock: 2162CSD17573Q5BT Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the FDMS7556S are selected based on strict electrical and mechanical compatibility criteria. The primary substitution logic is based on the following parameters:

Critical Matching Parameters:

• FET Type: N-Channel topology
• Technology: MOSFET (Metal Oxide)
• Drain to Source Voltage (Vdss): Minimum 25V rating
• Continuous Drain Current: Capability to handle 35A (Ta) or higher
• On-Resistance (Rds On): Performance at or below 1.2 mOhm specification
• Gate Threshold Voltage: Compatibility with 3V threshold
• Mounting Type: Surface Mount configuration
• Package Form Factor: 8-pin PowerTDFN or equivalent 5x6mm footprint

Substitution Categories:

Parametric Equivalent: FDMS7556S (onsemi) — Identical part number and specifications. Serves as direct replacement reference.

Similar Substitutes: Parts meeting or exceeding the electrical specifications of the FDMS7556S while maintaining surface mount compatibility. These include:

• CSD16415Q5T (Texas Instruments) — 25V, 100A continuous drain current, lower Rds On
• CSD17573Q5B (Texas Instruments) — 30V, 100A continuous drain current, lower Rds On
• CSD17573Q5BT (Texas Instruments) — 30V, 100A continuous drain current, lower Rds On

All substitute parts are active products with current manufacturing status, ensuring long-term availability and supply chain stability.

Parameter Comparison

Engineering Selection Recommendations

FDMS7556S (onsemi) — Parametric Equivalent

The FDMS7556S serves as the reference specification for this substitution analysis. As an obsolete product, direct replacement with this part number is not recommended for new designs. However, existing inventory of 1,216 pieces is available for legacy system support. This part maintains ROHS3 compliance and MSL Level 1 rating.

CSD16415Q5T (Texas Instruments) — Primary Substitute for 25V Applications

The CSD16415Q5T is an active product offering superior electrical performance within the same 25V voltage class. It provides 100A continuous drain current compared to the FDMS7556S 35A rating, with marginally lower on-resistance (1.15 mOhm @ 40A vs. 1.2 mOhm @ 35A). The 8-VSON-CLIP package maintains the 5x6mm footprint compatibility. This device is suitable for direct substitution in applications where the 25V rating is a design requirement. Inventory availability is 16,306 pieces. ROHS3 compliance and MSL Level 1 rating are maintained.

CSD17573Q5B (Texas Instruments) — Substitute for 30V-Rated Designs

The CSD17573Q5B is an active product offering enhanced voltage rating (30V) with 100A continuous drain current and superior on-resistance (1.0 mOhm @ 35A). This part is suitable for applications where the design voltage margin can accommodate the higher 30V rating. The 8-VSON-CLIP package maintains footprint compatibility. Inventory availability is 17,885 pieces. ROHS3 compliance and MSL Level 1 rating are maintained. This part is available in Cut Tape (CT) and Digi-Reel® packaging.

CSD17573Q5BT (Texas Instruments) — Substitute for 30V-Rated Designs with Tape & Reel Packaging

The CSD17573Q5BT is functionally identical to the CSD17573Q5B, offering 30V rating, 100A continuous drain current, and 1.0 mOhm on-resistance. The primary distinction is packaging format: this variant is supplied in Tape & Reel (TR) configuration, suitable for automated assembly processes. Inventory availability is 2,139 pieces. ROHS3 compliance and MSL Level 1 rating are maintained.

Selection Criteria Summary:

• For 25V maximum voltage applications: CSD16415Q5T
• For 30V maximum voltage applications: CSD17573Q5B (Cut Tape) or CSD17573Q5BT (Tape & Reel)
• All substitutes are active products with established supply chains
• All substitutes maintain ROHS3 compliance and MSL Level 1 rating
• All substitutes are compatible with -55°C to 150°C operating temperature range
• Package footprint compatibility (5x6mm) is maintained across all substitutes

Frequently Asked Questions (FAQ)

Q: Can the CSD16415Q5T directly replace the FDMS7556S in existing designs?

A: The CSD16415Q5T is electrically compatible with the FDMS7556S for applications operating at 25V or below. Both devices share the same 25V Vdss rating and maintain the 5x6mm surface mount footprint. The CSD16415Q5T provides superior current handling (100A vs. 35A) and comparable on-resistance performance. PCB layout and thermal management considerations should be evaluated based on specific application requirements.

Q: What is the difference between CSD17573Q5B and CSD17573Q5BT?

A: The CSD17573Q5B and CSD17573Q5BT are electrically identical devices with the same electrical specifications. The primary difference is packaging format: CSD17573Q5B is supplied in Cut Tape (CT) and Digi-Reel® format, while CSD17573Q5BT is supplied in Tape & Reel (TR) format. Selection between these variants depends on assembly process requirements and handling preferences.

Q: Are the Texas Instruments substitutes pin-compatible with the FDMS7556S?

A: The FDMS7556S uses an 8-PQFN package, while the Texas Instruments substitutes use an 8-VSON-CLIP package. Both packages are 8-pin configurations with 5x6mm footprints. Pin-to-pin compatibility must be verified against specific PCB layout and schematic requirements. Consult device datasheets for detailed pinout information.

Q: Can I use a 30V-rated device (CSD17573Q5B or CSD17573Q5BT) in a 25V application?

A: Yes. The 30V rating of the CSD17573Q5B and CSD17573Q5BT provides additional voltage margin in applications designed for 25V operation. These devices are suitable for use in 25V circuits and offer enhanced reliability through higher voltage headroom. No circuit modifications are required.

Q: What is the impact of lower gate threshold voltage in the Texas Instruments substitutes?

A: The Texas Instruments substitutes (CSD16415Q5T, CSD17573Q5B, CSD17573Q5BT) have lower gate threshold voltages (1.8V to 1.9V) compared to the FDMS7556S (3V). This characteristic affects gate drive requirements and switching behavior. Gate drive circuits must be evaluated to ensure compatibility with the lower threshold voltage. Consult device datasheets for detailed gate drive specifications.

Q: Are all substitute parts RoHS compliant?

A: Yes. The FDMS7556S and all listed substitute parts (CSD16415Q5T, CSD17573Q5B, CSD17573Q5BT) are ROHS3 compliant. All devices maintain MSL Level 1 (Unlimited) moisture sensitivity rating, indicating no special moisture control requirements during storage or handling.

Q: What is the availability status of substitute parts?

A: The FDMS7556S is classified as obsolete with 1,216 pieces in current inventory. All Texas Instruments substitutes are active products with established supply chains: CSD16415Q5T (16,306 pieces), CSD17573Q5B (17,885 pieces), and CSD17573Q5BT (2,139 pieces) are available in inventory.

Q: How do the on-resistance specifications compare across all parts?

A: The FDMS7556S specifies 1.2 mOhm maximum on-resistance at 35A and 10V gate voltage. The CSD16415Q5T specifies 1.15 mOhm at 40A and 10V. The CSD17573Q5B and CSD17573Q5BT specify 1.0 mOhm at 35A and 10V. All substitutes meet or exceed the on-resistance performance of the FDMS7556S, resulting in lower conduction losses and reduced thermal dissipation.

Q: What thermal performance differences exist between these devices?

A: The FDMS7556S specifies 2.5W (Ta) and 96W (Tc) maximum power dissipation. The Texas Instruments substitutes specify 3.2W (Ta) and 195W (Tc) for CSD16415Q5T, and 3.2W (Ta) and 195W (Tc) for CSD17573Q5B and CSD17573Q5BT. The higher Tc ratings in the substitutes indicate improved thermal performance under case temperature conditions, enabling higher power handling capability.