STTH20R04W Equivalent & Substitute Parts

Part Overview

The STTH20R04W is a general-purpose rectifier diode manufactured by STMicroelectronics, rated for 400 V DC reverse voltage and 20 A average rectified current in a DO-247 through-hole package. This device is classified as obsolete, which necessitates identification of equivalent and substitute components for ongoing design support and procurement continuity. Substitute parts must maintain electrical compatibility across voltage, current, and thermal specifications while accommodating package variations in modern active product lines.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	400	V
Current - Average Rectified (Io)	20	A
Voltage - Forward (Vf) (Max) @ If	1.7 @ 20 A	V
Reverse Recovery Time (trr)	45	ns
Current - Reverse Leakage @ Vr	20	µA @ 400 V
Speed Classification	Fast Recovery ≤ 500ns, > 200mA (Io)	—
Mounting Type	Through Hole	—
Package / Case	DO-247-2	—
Operating Temperature - Junction (Max)	175	°C
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the STTH20R04W is determined by the following critical electrical and mechanical parameters:

Voltage Compatibility: All substitute parts must maintain a DC reverse voltage rating of 400 V or greater to ensure safe operation within the original circuit design envelope.

Current Rating: Substitute parts must support the 20 A average rectified current requirement. Parts with higher current ratings (30 A, 60 A) are acceptable as they provide design margin and do not degrade circuit performance.

Speed Classification: All candidates maintain fast recovery characteristics (≤ 500ns, > 200mA), ensuring compatibility with switching applications and transient response requirements.

Mounting and Package: Through-hole mounting is required. The original DO-247-2 package is compatible with TO-247-2 and TO-247 [B] variants, as these share identical lead spacing and footprint geometry.

Compliance and Status: Substitute parts must maintain ROHS3 compliance and active product status to ensure long-term availability and regulatory alignment.

Parameter Comparison

Parameter	STTH20R04W (Main)	APT30D40BG (Substitute)	FFH60UP40S (Substitute)
Manufacturer	STMicroelectronics	Microchip Technology	onsemi
Voltage - DC Reverse (Vr) (Max)	400 V	400 V	400 V
Current - Average Rectified (Io)	20 A	30 A	60 A
Voltage - Forward (Vf) (Max) @ If	1.7 V @ 20 A	1.5 V @ 30 A	1.3 V @ 60 A
Reverse Recovery Time (trr)	45 ns	32 ns	85 ns
Current - Reverse Leakage @ Vr	20 µA @ 400 V	250 µA @ 400 V	100 µA @ 400 V
Speed Classification	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	DO-247-2	TO-247-2	TO-247-2
Operating Temperature - Junction	175°C (Max)	-55°C ~ 175°C	-65°C ~ 150°C
Product Status	Obsolete	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

APT30D40BG (Microchip Technology): This substitute provides 30 A current capacity with identical 400 V voltage rating. The device is in active production status, ensuring long-term availability. The TO-247-2 package is mechanically compatible with the original DO-247-2 footprint. Forward voltage is lower (1.5 V @ 30 A), reducing power dissipation. Reverse recovery time is faster (32 ns), improving switching efficiency. Reverse leakage current is elevated (250 µA @ 400 V) compared to the original specification but remains within acceptable limits for general-purpose rectification. Operating temperature range extends to -55°C, providing enhanced thermal margin.

FFH60UP40S (onsemi): This substitute provides 60 A current capacity, offering significant design margin above the 20 A requirement. The 400 V voltage rating matches the original specification. Active product status ensures procurement continuity. The TO-247-2 package is mechanically compatible. Forward voltage is substantially lower (1.3 V @ 60 A), resulting in reduced thermal load. Reverse recovery time is longer (85 ns) than the original, which may impact high-frequency switching applications. Reverse leakage current is moderate (100 µA @ 400 V). Operating temperature maximum is 150°C, which is 25°C lower than the original specification and should be evaluated for thermal margin in high-temperature environments.

Both substitutes maintain ROHS3 compliance and fast recovery speed classification. Selection between APT30D40BG and FFH60UP40S depends on application-specific requirements for current margin, thermal dissipation, and operating temperature range.

Frequently Asked Questions (FAQ)

Q: Can the APT30D40BG directly replace the STTH20R04W without circuit modification?

A: Yes. The APT30D40BG maintains the same 400 V voltage rating and exceeds the 20 A current requirement. The TO-247-2 package is mechanically and electrically compatible with the DO-247-2 footprint. No circuit modifications are required.

Q: What is the significance of the higher current rating in substitute parts?

A: Higher current ratings (30 A, 60 A) provide design margin and reduce thermal stress on the component. The device operates below its maximum rated current, extending component life and improving reliability. This is a beneficial characteristic in substitution.

Q: How does forward voltage affect circuit performance?

A: Lower forward voltage in substitute parts (APT30D40BG: 1.5 V, FFH60UP40S: 1.3 V versus original 1.7 V) reduces power dissipation and heat generation. This improves overall circuit efficiency and thermal management.

Q: Are there package compatibility concerns between DO-247-2 and TO-247-2?

A: No. DO-247-2 and TO-247-2 packages share identical lead spacing, pitch, and through-hole footprint geometry. They are mechanically and electrically interchangeable on standard PCB layouts.

Q: Why is reverse recovery time different across substitute parts?

A: Reverse recovery time varies based on semiconductor manufacturing process and doping profile. The STTH20R04W has 45 ns, APT30D40BG has 32 ns (faster), and FFH60UP40S has 85 ns (slower). All remain within the fast recovery classification (≤ 500ns). Faster recovery reduces switching losses; slower recovery may increase switching losses in high-frequency applications.

Q: What does the obsolete status of the STTH20R04W mean for procurement?

A: Obsolete status indicates the manufacturer has discontinued production. Existing inventory may be available from distributors, but long-term supply is not guaranteed. Substitution with active products (APT30D40BG, FFH60UP40S) ensures reliable future procurement and design continuity.

Q: How should reverse leakage current differences be evaluated?

A: The STTH20R04W specifies 20 µA @ 400 V. APT30D40BG specifies 250 µA, and FFH60UP40S specifies 100 µA. Higher leakage increases standby power consumption and heat generation. For most general-purpose rectification applications, these differences are negligible. High-impedance or precision analog circuits may require evaluation of leakage impact.

Q: Is the lower maximum junction temperature of FFH60UP40S a limitation?

A: FFH60UP40S has a maximum junction temperature of 150°C versus 175°C for the original. In applications where the junction temperature approaches or exceeds 150°C, thermal margin is reduced. Verify thermal design calculations to ensure the device operates safely within this limit.

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