S4X8ESAP Equivalent & Substitute Parts

Part Overview

The S4X8ESAP is a 400V, 800mA sensitive gate SCR (Silicon Controlled Rectifier) manufactured by Littelfuse Inc. in TO-92 through-hole package. This thyristor is designed for general-purpose switching and control applications requiring moderate voltage and current ratings with sensitive gate triggering characteristics. The part is currently active in production status with 1034 units in stock. Equivalent and substitute parts are identified based on matching electrical performance parameters and package compatibility to support design flexibility and supply chain continuity.

Key Parameters

Parameter	Value	Unit
Voltage - Off State	400	V
Voltage - Gate Trigger (Vgt) Max	800	mV
Current - Gate Trigger (Igt) Max	200	µA
Voltage - On State (Vtm) Max	1.7	V
Current - On State (It RMS) Max	800	mA
Current - Hold (Ih) Max	5	mA
Operating Temperature Range	-40 to 125	°C
Package / Case	TO-92-3 (TO-226AA)	—
Mounting Type	Through Hole	—
SCR Type	Sensitive Gate	—

Substitute Part Grouping Explanation

Substitution eligibility for the S4X8ESAP is determined by the following critical parameters:

Off-state voltage rating: 400V minimum
On-state RMS current rating: 800mA minimum
Gate trigger voltage (Vgt): 800mV maximum
Gate trigger current (Igt): 200µA maximum
On-state voltage drop (Vtm): 1.7V to 1.95V acceptable range
Package and mounting: TO-92-3 through-hole configuration
SCR type: Sensitive gate classification
Operating temperature: -40°C to 125°C
Compliance: ROHS3 compliant, REACH unaffected

Substitute parts are grouped into two categories: parametric equivalents (matching all critical electrical specifications) and manufacturer-recommended alternatives (meeting functional requirements with minor parameter variations within acceptable design margins).

Parameter Comparison

Parameter	S4X8ESAP (Littelfuse)	S402ESAP (Littelfuse)	P0102DA 1AA3 (STMicroelectronics)	P0102DA 2AL3 (STMicroelectronics)	P0102DA 5AL3 (STMicroelectronics)	P0109DA 5AL3 (STMicroelectronics)	P0118DA 5AL3 (STMicroelectronics)
Voltage - Off State (V)	400	400	400	400	400	400	400
Voltage - Gate Trigger Max (mV)	800	800	800	800	800	800	800
Current - Gate Trigger Max (µA)	200	200	200	200	200	200	5
Voltage - On State Max (V)	1.7	1.7	1.95	1.95	1.95	1.95	1.95
Current - On State RMS Max (mA)	800	1500	800	800	800	800	800
Current - Hold Max (mA)	5	5	5	5	5	5	5
Operating Temperature (°C)	-40 to 125	-40 to 125	-40 to 125	-40 to 125	-40 to 125	-40 to 125	-40 to 125
Package / Case	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3
Manufacturer	Littelfuse Inc.	Littelfuse Inc.	STMicroelectronics	STMicroelectronics	STMicroelectronics	STMicroelectronics	STMicroelectronics
Product Status	Active	Active	Active	Active	Active	Active	Obsolete
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitute - S402ESAP (Littelfuse Inc.)

The S402ESAP is a direct parametric equivalent with identical gate trigger specifications and on-state voltage characteristics. This part offers higher on-state RMS current capability (1.5A vs. 800mA), providing design margin for applications approaching the S4X8ESAP current limit. Both parts are manufactured by Littelfuse Inc., ensuring consistent design philosophy and reliability. Active production status with 3061 units in stock supports immediate availability.

Secondary Substitutes - P0102DA Series (STMicroelectronics)

The P0102DA 1AA3, P0102DA 2AL3, and P0102DA 5AL3 are manufacturer-recommended alternatives from STMicroelectronics. All three variants maintain identical electrical performance for gate triggering (800mV, 200µA) and on-state current (800mA RMS). The on-state voltage (1.95V) is slightly elevated compared to the S4X8ESAP (1.7V) but remains within acceptable design margins for most applications. These parts are ROHS3 compliant and actively produced, with P0102DA 5AL3 offering the highest inventory availability (35,300 units).

Alternative Substitute - P0109DA 5AL3 (STMicroelectronics)

The P0109DA 5AL3 meets all critical electrical specifications matching the S4X8ESAP performance envelope. This part is actively produced with 3567 units in stock and provides cross-manufacturer substitution capability.

Not Recommended - P0118DA 5AL3 (STMicroelectronics)

The P0118DA 5AL3 is marked as obsolete product status and should not be selected for new designs despite meeting electrical specifications. The significantly reduced gate trigger current requirement (5µA vs. 200µA) indicates a different device generation and may introduce compatibility issues with existing gate drive circuits designed for the S4X8ESAP.

Frequently Asked Questions (FAQ)

Q: Can I use S402ESAP as a direct replacement for S4X8ESAP?

A: Yes. The S402ESAP is a parametric equivalent with matching gate trigger specifications (800mV, 200µA) and identical on-state voltage (1.7V). The higher current rating (1.5A vs. 800mA) provides additional design margin without affecting circuit operation. Both parts use TO-92-3 through-hole packaging and are pin-compatible.

Q: What is the difference between Littelfuse and STMicroelectronics versions?

A: Both manufacturers produce sensitive gate SCRs meeting the 400V, 800mA specification. The primary difference is on-state voltage: Littelfuse S4X8ESAP and S402ESAP specify 1.7V maximum, while STMicroelectronics P0102DA and P0109DA series specify 1.95V maximum. This 0.25V difference is within acceptable design margins for most applications but should be evaluated for power dissipation-critical designs.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts (S402ESAP, P0102DA 1AA3, P0102DA 2AL3, P0102DA 5AL3, P0109DA 5AL3) are ROHS3 compliant. The P0118DA 5AL3 is also ROHS3 compliant but is obsolete and not recommended for new designs.

Q: What packaging options are available?

A: All substitute parts are supplied in TO-92-3 through-hole package with formed leads. Packaging formats vary by supplier: S4X8ESAP is supplied in Tape & Box (TB), S402ESAP in Cut Tape (CT), and STMicroelectronics parts in Bulk or Cut Tape (CT) formats. Physical package dimensions and pin configuration are identical across all parts.

Q: Can I use P0118DA 5AL3 in a new design?

A: No. The P0118DA 5AL3 is marked as obsolete product status. While it meets electrical specifications, obsolete parts present long-term supply risk and should not be selected for new designs. Use active production alternatives such as P0102DA 5AL3 or P0109DA 5AL3 instead.

Q: What is the gate trigger current difference in P0118DA 5AL3?

A: The P0118DA 5AL3 specifies 5µA maximum gate trigger current compared to 200µA for the S4X8ESAP. This significant reduction indicates a different device generation with potentially different gate drive circuit requirements. Existing designs optimized for 200µA gate current may not operate reliably with this part.

Q: Which substitute offers the best inventory availability?

A: The P0102DA 5AL3 (STMicroelectronics) offers the highest inventory with 35,300 units in stock, followed by P0102DA 2AL3 with 10,100 units. For Littelfuse products, S402ESAP provides 3061 units in stock.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message