SI4435DY P-Channel MOSFET 30V 8A Equivalent & Substitute Parts

Part Overview

The SI4435DY is a P-Channel MOSFET manufactured by Infineon Technologies, rated for 30V drain-to-source voltage and 8A continuous drain current in an 8-SO surface mount package. This device is classified as Obsolete, indicating it has reached end-of-life status and is no longer recommended for new designs. The HEXFET® series device delivers 2.5W maximum power dissipation and operates across the temperature range of -55°C to 150°C (TJ).

Due to its obsolete status, equivalent and substitute parts are necessary for ongoing production support, maintenance applications, and design continuity. Suitable alternatives maintain the core electrical specifications while offering improved availability and compliance status.

Key Parameters

Parameter	Value	Unit
FET Type	P-Channel	—
Drain-to-Source Voltage (Vdss)	30	V
Continuous Drain Current (Id) @ 25°C	8	A (Tc)
On-Resistance (Rds On) @ 8A, 10V	20	mOhm
Gate Threshold Voltage (Vgs(th)) @ 250µA	1	V
Gate Charge (Qg) @ 10V	60	nC
Maximum Gate Voltage (Vgs)	±20	V
Input Capacitance (Ciss) @ 15V	2320	pF
Power Dissipation (Max)	2.5	W (Ta)
Operating Temperature Range	-55 to 150	°C (TJ)
Mounting Type	Surface Mount	—
Package	8-SOIC (0.154", 3.90mm Width)	—

Substitute Part Grouping Explanation

Substitution eligibility for the SI4435DY is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Drain-to-Source Voltage (Vdss): Must equal or exceed 30V
Continuous Drain Current (Id): Must equal or exceed 8A
On-Resistance (Rds On): Must not exceed 20mOhm at rated current and gate voltage
Gate Threshold Voltage (Vgs(th)): Must be compatible with 4.5V to 10V drive voltage range
Maximum Gate Voltage (Vgs): Must support ±20V minimum
Operating Temperature Range: Must span -55°C to 150°C (TJ)
Mounting Type: Surface Mount required
Package Form Factor: 8-SOIC (0.154", 3.90mm Width) required

Secondary Considerations:

Gate Charge (Qg) and Input Capacitance (Ciss) affect switching performance but do not disqualify substitutes
Power Dissipation capability may vary; higher ratings provide design margin
Product Status and RoHS compliance affect long-term availability and regulatory requirements

Substitute parts are grouped into two categories: Direct Equivalents (matching all primary criteria) and Functional Alternatives (meeting electrical requirements with minor parameter variations).

Parameter Comparison

Part Number	Manufacturer	Vdss (V)	Id @ 25°C (A)	Rds On @ 10V (mOhm)	Vgs(th) @ 250µA (V)	Qg @ 10V (nC)	Ciss @ 15V (pF)	Power Diss. (W)	Package	Status
SI4435DY	Infineon	30	8	20	1	60	2320	2.5	8-SOIC	Obsolete
SI4435DYTRPBF	Infineon	30	8	20	1	60	2320	2.5	8-SOIC	Active
AO4419	Alpha & Omega	30	9.7	20	2.7	32	1900	3.1	8-SOIC	Active
AO4411	Alpha & Omega	30	8	32	2.4	16	760	3.1	8-SOIC	Not For New Designs
DMP3036SSS-13	Diodes Inc.	30	19.5	20	3	16.5	1931	1.4	8-SOIC	Active
FDS4435A	onsemi	30	9	17	2	30	2010	2.5	8-SOIC	Obsolete
FDS4435BZ	onsemi	30	8.8	20	3	40	1845	2.5	8-SOIC	Active
RS3E075ATTB	Rohm	30	—	23.5	2.5	25	1250	2	8-SOIC	Not For New Designs

Engineering Selection Recommendations

Direct Equivalent (Recommended Primary Choice):

SI4435DYTRPBF (Infineon Technologies) is the direct equivalent to SI4435DY. This part maintains identical electrical specifications across all parameters: 30V Vdss, 8A continuous drain current, 20mOhm Rds On, and 2.5W power dissipation. The critical distinction is product status: SI4435DYTRPBF is Active, whereas the original SI4435DY is Obsolete. SI4435DYTRPBF carries RoHS3 compliance and is available in Cut Tape and Digi-Reel® packaging with 17,394 units in stock, providing superior long-term availability and regulatory alignment.

Active Alternatives for Enhanced Performance:

FDS4435BZ (onsemi PowerTrench® series) qualifies as a functional substitute. It delivers 8.8A continuous drain current (exceeding the 8A requirement), maintains 20mOhm Rds On at rated current, and provides 2.5W power dissipation matching the original. Product status is Active with RoHS3 compliance. Gate threshold voltage is 3V, requiring verification against 4.5V minimum drive voltage specifications in the target application.

AO4419 (Alpha & Omega Semiconductor) offers enhanced current capability at 9.7A with 20mOhm Rds On and 3.1W power dissipation. This part is Active and RoHS3 compliant. Gate threshold voltage of 2.7V and reduced input capacitance (1900 pF versus 2320 pF) may improve switching performance in certain circuit topologies. Higher power dissipation provides additional thermal margin.

DMP3036SSS-13 (Diodes Incorporated) provides the highest current rating at 19.5A continuous drain current with 20mOhm Rds On. Power dissipation is reduced to 1.4W, offering superior thermal performance. This part is Active and RoHS3 compliant. The higher current rating and lower power dissipation make this suitable for applications requiring design margin or thermal optimization.

Legacy Alternatives (Not Recommended for New Designs):

AO4411 and RS3E075ATTB are marked "Not For New Designs" and should be avoided for new product development. FDS4435A is Obsolete and presents the same end-of-life risk as the original SI4435DY.

Selection Logic:

For direct replacement in existing production: Use SI4435DYTRPBF.

For new designs requiring active product status: Select from FDS4435BZ, AO4419, or DMP3036SSS-13 based on thermal and current requirements.

All recommended substitutes maintain 8-SOIC package compatibility, -55°C to 150°C operating temperature range, and ±20V maximum gate voltage specification.

Frequently Asked Questions (FAQ)

Q: Can SI4435DYTRPBF be used as a direct replacement for SI4435DY in existing designs?

A: Yes. SI4435DYTRPBF is electrically and mechanically identical to SI4435DY. Both parts share the same Infineon HEXFET® series, identical Vdss (30V), Id (8A), Rds On (20mOhm), and package (8-SOIC). The primary difference is product status: SI4435DYTRPBF is Active while SI4435DY is Obsolete. No circuit modifications are required.

Q: What is the difference between the "Tc" and "Ta" current ratings shown in the specifications?

A: Tc denotes current rating at case temperature (25°C), while Ta denotes current rating at ambient temperature (25°C). Both specifications are provided by manufacturers to clarify thermal conditions. For the SI4435DY and SI4435DYTRPBF, the 8A rating is specified at Tc (case temperature). Verify your application's thermal environment to confirm adequate current capacity.

Q: Can I use AO4419 (9.7A) instead of SI4435DY (8A) without circuit changes?

A: AO4419 meets all primary substitution criteria: 30V Vdss, 20mOhm Rds On, ±20V Vgs maximum, and 8-SOIC package. The higher 9.7A rating provides design margin. However, gate threshold voltage differs (2.7V for AO4419 versus 1V for SI4435DY). Verify that your gate drive voltage (minimum 4.5V, typical 10V) is sufficient to fully enhance the AO4419. Input capacitance is also lower (1900 pF versus 2320 pF), which may affect switching transients in high-frequency applications.

Q: Why does DMP3036SSS-13 have lower power dissipation (1.4W) than SI4435DY (2.5W) despite higher current rating?

A: Power dissipation is calculated as P = I²R. DMP3036SSS-13 achieves 19.5A continuous current with 20mOhm Rds On, while SI4435DY delivers 8A at 20mOhm. The lower power dissipation reflects superior die design and thermal management in the Diodes Incorporated part. This is a performance advantage, not a limitation.

Q: Are all substitute parts RoHS compliant?

A: All recommended active substitutes (SI4435DYTRPBF, AO4419, DMP3036SSS-13, FDS4435BZ) carry RoHS3 compliance. The original SI4435DY is RoHS non-compliant. Legacy parts AO4411 and RS3E075ATTB are RoHS3 compliant but marked "Not For New Designs." Verify RoHS requirements for your application before final part selection.

Q: Can I mix SI4435DY and SI4435DYTRPBF in the same production batch?

A: Electrically and mechanically, yes. Both parts are identical in function and package. However, mixing obsolete and active parts in production creates supply chain risk. It is recommended to transition entirely to SI4435DYTRPBF to ensure consistent long-term availability and compliance status.

Q: What is the significance of the "8-SO" versus "8-SOIC" package designation?

A: Both designations refer to the same 8-pin surface-mount package with 0.154" (3.90mm) width. "SO" (Small Outline) and "SOIC" (Small Outline Integrated Circuit) are equivalent terms used by different manufacturers. All substitute parts listed are compatible with PCB layouts designed for SI4435DY.

Q: Does gate charge (Qg) affect substitutability?

A: Gate charge influences switching speed and gate drive circuit design but does not disqualify substitutes. SI4435DY specifies 60 nC at 10V. Substitutes range from 16 nC (AO4411) to 60 nC (SI4435DYTRPBF). Lower gate charge reduces switching losses and gate drive power consumption. Verify that your gate drive circuit can supply adequate current for the selected part's gate charge and switching frequency.

Q: Is input capacitance (Ciss) a critical parameter for substitution?

A: Input capacitance affects gate drive circuit impedance and switching transients but is not a disqualification criterion. SI4435DY specifies 2320 pF at 15V. Substitutes range from 760 pF (AO4411) to 2320 pF (SI4435DYTRPBF). Lower capacitance reduces gate drive current requirements and may improve high-frequency performance. Verify compatibility with your gate drive circuit design.

Q: Can FDS4435A or FDS4435BZ be used interchangeably?

A: No. FDS4435A is Obsolete, while FDS4435BZ is Active. Although both are onsemi PowerTrench® devices in 8-SOIC packages with 30V Vdss and 20mOhm Rds On, FDS4435BZ is the recommended choice for new designs and ongoing production. FDS4435A presents the same end-of-life risk as SI4435DY.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message