S4004VS2 Equivalent & Substitute Parts

Part Overview

The S4004VS2 is a 400V 4A sensitive gate SCR (silicon-controlled rectifier) in TO-251 packaging manufactured by Littelfuse Inc. This thyristor is designed for applications requiring controlled rectification and switching at moderate voltage and current levels. The part is currently discontinued at DiGi Electronics, making equivalent substitutes necessary for ongoing production and maintenance applications. Substitute parts must maintain electrical compatibility across voltage ratings, gate trigger characteristics, and thermal operating ranges while accommodating packaging variations.

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)	1.6	V
Current - On State (It (RMS)) (Max)	4	A
Current - Hold (Ih) (Max)	6	mA
Operating Temperature Range	-40 to 110	°C
SCR Type	Sensitive Gate	-
Mounting Type	Through Hole	-

Substitute Part Grouping Explanation

Substitution eligibility for the S4004VS2 is determined by the following critical parameters:

Off-state voltage rating of 400V minimum
Gate trigger voltage (Vgt) not exceeding 800mV
Gate trigger current (Igt) of 200µA maximum
On-state voltage (Vtm) not exceeding 1.6V
RMS on-state current rating of 4A minimum
Hold current (Ih) of 6mA maximum
Through-hole mounting configuration
Sensitive gate SCR type classification

Two substitute parts meet these criteria with documented electrical compatibility:

S4004VS2TP (Littelfuse Inc.) - Direct manufacturer variant with identical electrical specifications and packaging designation change from TO-251 to TO-251AA.

BT148-400R,127 (WeEn Semiconductors) - Cross-manufacturer substitute with equivalent voltage and current ratings, packaged in SOT-82-3 through-hole configuration.

Parameter Comparison

Parameter	S4004VS2	S4004VS2TP	BT148-400R,127
Voltage - Off State (V)	400	400	400
Voltage - Gate Trigger (Vgt) (Max) (mV)	800	800	1500
Current - Gate Trigger (Igt) (Max) (µA)	200	200	200
Voltage - On State (Vtm) (Max) (V)	1.6	1.6	1.8
Current - On State (It (RMS)) (Max) (A)	4	4	4
Current - Hold (Ih) (Max) (mA)	6	6	6
Current - Off State (Max) (µA)	2	2	500
Operating Temperature Range (°C)	-40 to 110	-40 to 110	-40 to 125
SCR Type	Sensitive Gate	Sensitive Gate	Sensitive Gate
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	TO-251-3	TO-251-3	SOT-82
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

S4004VS2TP is the primary substitute option. It is manufactured by Littelfuse Inc., the original equipment manufacturer, with identical electrical specifications and active product status. This part achieves ROHS3 compliance, addressing regulatory requirements that the original S4004VS2 does not meet. The packaging designation differs (TO-251AA versus TO-251), but both are through-hole TO-251 variants with compatible pinouts and lead configurations. Inventory availability is higher at 2112 pieces.

BT148-400R,127 is a secondary cross-manufacturer substitute from WeEn Semiconductors. This part maintains the 400V voltage rating and 4A RMS current capability with active product status and ROHS3 compliance. The gate trigger voltage specification is higher at 1500mV maximum compared to 800mV, and off-state leakage current is elevated at 500µA versus 2µA. The SOT-82-3 package is a through-hole configuration compatible with board-level integration. This option provides higher inventory availability at 10714 pieces and extended operating temperature range to 125°C.

Frequently Asked Questions (FAQ)

Q: Can S4004VS2TP be used as a direct replacement for S4004VS2?

A: Yes. S4004VS2TP is a direct manufacturer substitute with identical electrical specifications. Both parts are TO-251 through-hole packages with compatible pinouts. The primary difference is packaging designation (TO-251AA) and RoHS compliance status.

Q: What are the key differences between S4004VS2TP and BT148-400R,127?

A: Both parts share the same 400V voltage rating and 4A RMS current capability. S4004VS2TP maintains the original gate trigger voltage of 800mV maximum, while BT148-400R,127 has a higher specification at 1500mV. BT148-400R,127 exhibits higher off-state leakage current (500µA versus 2µA) and operates to 125°C versus 110°C. Package types differ: S4004VS2TP uses TO-251-3, while BT148-400R,127 uses SOT-82-3.

Q: Are packaging differences between TO-251 and SOT-82 significant for board integration?

A: Both are through-hole packages with three leads. Physical dimensions and lead spacing differ. PCB layout modifications may be required when substituting between these package types. Verify footprint compatibility with your circuit board design before implementation.

Q: Does the higher gate trigger voltage of BT148-400R,127 affect circuit operation?

A: The BT148-400R,127 requires up to 1500mV gate trigger voltage compared to 800mV for the original part. Gate drive circuits must supply sufficient voltage to reliably trigger the device. Existing gate drive designs optimized for 800mV may require adjustment.

Q: What is the significance of RoHS compliance for these parts?

A: S4004VS2 is RoHS non-compliant. Both S4004VS2TP and BT148-400R,127 are ROHS3 compliant, meeting current environmental and regulatory standards for electronic components in most markets.

Q: Which substitute offers the best inventory availability?

A: BT148-400R,127 has the highest inventory at 10714 pieces. S4004VS2TP has 2112 pieces available. Both exceed typical component stock levels for active products.

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