STTA812D Equivalent & Substitute Parts

Part Overview

The STTA812D is a general-purpose rectifier diode manufactured by STMicroelectronics, rated for 1200 V DC reverse voltage and 8 A average rectified current in a TO-220AC through-hole package. This device is part of the TURBOSWITCH™ series and features fast recovery characteristics with a reverse recovery time of 100 ns. The STTA812D is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Voltage - DC Reverse (Vr) (Max)	1200 V
Current - Average Rectified (Io)	8 A
Voltage - Forward (Vf) (Max) @ If	2.2 V @ 8 A
Reverse Recovery Time (trr)	100 ns
Current - Reverse Leakage @ Vr	100 µA @ 1200 V
Mounting Type	Through Hole
Package / Case	TO-220-2
Operating Temperature - Junction (Max)	150°C
Technology	Standard
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the STTA812D are selected based on the following critical parameters that determine functional compatibility:

Primary Matching Criteria:

Voltage - DC Reverse (Vr) (Max): 1200 V (all substitutes match)
Package / Case: TO-220-2 (all substitutes match)
Mounting Type: Through Hole (all substitutes match)
Technology: Standard (all substitutes match)
RoHS Status: ROHS3 Compliant (all substitutes match)

Secondary Consideration Parameters:

Current - Average Rectified (Io): Substitutes range from 8 A to 30 A
Reverse Recovery Time (trr): Substitutes range from 40 ns to 100 ns
Operating Temperature - Junction: Substitutes range from 150°C to 175°C
Current - Reverse Leakage @ Vr: Substitutes range from 8 µA to 750 µA

All listed substitute parts maintain the same voltage rating and package form factor as the STTA812D, enabling direct replacement in circuit designs. Differences in current rating, recovery time, and leakage characteristics reflect variations in device technology and performance class.

Parameter Comparison

Parameter	STTA812D	STTH812D	DSEI20-12A	DSEP29-12A	DSEP8-12A
Manufacturer	STMicroelectronics	STMicroelectronics	IXYS	IXYS	IXYS
Voltage - DC Reverse (Vr) (Max)	1200 V	1200 V	1200 V	1200 V	1200 V
Current - Average Rectified (Io)	8 A	8 A	17 A	30 A	10 A
Voltage - Forward (Vf) (Max) @ If	2.2 V @ 8 A	2.2 V @ 8 A	2.15 V @ 12 A	2.75 V @ 30 A	2.94 V @ 10 A
Reverse Recovery Time (trr)	100 ns	100 ns	60 ns	40 ns	40 ns
Current - Reverse Leakage @ Vr	100 µA @ 1200 V	8 µA @ 1200 V	750 µA @ 1200 V	250 µA @ 1200 V	60 µA @ 1200 V
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-220-2	TO-220-2	TO-220-2	TO-220-2	TO-220-2
Operating Temperature - Junction (Max)	150°C	175°C	150°C	175°C	175°C
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

STTH812D (STMicroelectronics)

The STTH812D is the direct active equivalent to the obsolete STTA812D. Both devices share identical voltage rating (1200 V), current rating (8 A), forward voltage (2.2 V @ 8 A), and package form factor (TO-220-2). The STTH812D offers improved reverse leakage performance (8 µA versus 100 µA) and higher maximum junction temperature (175°C versus 150°C). This part is actively manufactured and ROHS3 compliant, making it the primary replacement for the STTA812D.

DSEP8-12A (IXYS)

The DSEP8-12A provides a functionally compatible alternative with matching 1200 V voltage rating and 10 A current rating. This device features superior reverse recovery time (40 ns versus 100 ns) and lower reverse leakage (60 µA versus 100 µA). The DSEP8-12A is part of the HiPerFRED™ series and supports extended operating temperature range (-55°C to 175°C). This part is actively manufactured and ROHS3 compliant.

DSEI20-12A (IXYS)

The DSEI20-12A maintains the 1200 V voltage rating with elevated current capacity (17 A). This device offers faster recovery time (60 ns) and lower forward voltage (2.15 V @ 12 A). The DSEI20-12A is suitable for applications requiring higher current handling within the same voltage class. This part is actively manufactured and ROHS3 compliant.

DSEP29-12A (IXYS)

The DSEP29-12A maintains the 1200 V voltage rating with significantly elevated current capacity (30 A). This device features the fastest recovery time (40 ns) among all substitutes. The DSEP29-12A is part of the HiPerFRED™ series and supports extended operating temperature range (-55°C to 175°C). This part is actively manufactured and ROHS3 compliant.

Frequently Asked Questions (FAQ)

Q: Can the STTH812D directly replace the STTA812D without circuit modification?

A: Yes. The STTH812D is the direct active equivalent with identical electrical ratings (1200 V, 8 A) and package form factor (TO-220-2). Both devices are through-hole mounted and ROHS3 compliant. The STTH812D offers improved performance characteristics with lower reverse leakage and higher maximum junction temperature.

Q: What is the difference between the STTA812D and STTH812D?

A: Both devices share the same voltage (1200 V), current (8 A), forward voltage (2.2 V @ 8 A), and package (TO-220-2). The STTH812D provides lower reverse leakage current (8 µA versus 100 µA) and higher maximum junction temperature (175°C versus 150°C). The STTA812D is obsolete while the STTH812D is actively manufactured.

Q: Can I use the DSEP8-12A as a substitute for the STTA812D?

A: Yes. The DSEP8-12A maintains the same 1200 V voltage rating and TO-220-2 package. The 10 A current rating exceeds the STTA812D requirement (8 A), and the device offers superior reverse recovery time (40 ns versus 100 ns) and lower reverse leakage (60 µA versus 100 µA). This part is actively manufactured and ROHS3 compliant.

Q: What are the advantages of using IXYS HiPerFRED™ devices (DSEP8-12A, DSEP29-12A) over the STMicroelectronics alternatives?

A: The IXYS HiPerFRED™ series devices feature faster reverse recovery times (40 ns versus 100 ns for STTA812D) and extended operating temperature ranges (-55°C to 175°C). These characteristics reduce switching losses and enable operation in wider temperature environments. Both DSEP8-12A and DSEP29-12A maintain the 1200 V voltage rating and TO-220-2 package compatibility.

Q: Can I use a higher current-rated device like the DSEP29-12A (30 A) in place of the STTA812D (8 A)?

A: Yes. The DSEP29-12A maintains the same 1200 V voltage rating and TO-220-2 package form factor. Higher current rating does not prevent substitution in circuits designed for lower current. The DSEP29-12A offers superior performance with faster recovery time (40 ns) and lower reverse leakage (250 µA). Thermal management and PCB layout considerations remain unchanged.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts (STTH812D, DSEI20-12A, DSEP29-12A, DSEP8-12A) are ROHS3 compliant and REACH unaffected, matching the compliance status of the STTA812D.

Q: What is the significance of reverse recovery time in selecting a substitute?

A: Reverse recovery time (trr) affects switching speed and switching losses. The STTA812D has 100 ns recovery time. Substitute parts offer faster recovery: STTH812D (100 ns), DSEI20-12A (60 ns), DSEP8-12A (40 ns), and DSEP29-12A (40 ns). Faster recovery reduces power dissipation in high-frequency switching applications.

Q: Do all substitute parts use the same TO-220-2 package?

A: Yes. All substitute parts (STTH812D, DSEI20-12A, DSEP29-12A, DSEP8-12A) use the TO-220-2 package with through-hole mounting, ensuring mechanical and thermal compatibility with existing PCB designs.

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