BAS45A,133 Equivalent & Substitute Parts

Part Overview

The BAS45A,133 is a general-purpose rectifier diode manufactured by Nexperia USA Inc., rated for 125 V DC reverse voltage and 250 mA average rectified current in a DO-34 axial through-hole package. This component is classified as Active product status and is ROHS3 compliant. Substitute parts are identified when equivalent electrical performance and mechanical compatibility are required due to inventory constraints, manufacturing discontinuation, or design flexibility needs.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	125	V
Current - Average Rectified (Io)	250	mA
Voltage - Forward (Vf) (Max) @ If	1 V @ 100 mA	V
Reverse Recovery Time (trr)	1.5	µs
Current - Reverse Leakage @ Vr	1	nA @ 125 V
Capacitance @ Vr, F	4	pF @ 0V, 1MHz
Package / Case	DO-204AG, DO-34, Axial	—
Mounting Type	Through Hole	—
Operating Temperature - Junction (Max)	175	°C
Technology	Standard	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitute parts for the BAS45A,133 are classified into two categories based on electrical and mechanical compatibility:

Parametric Equivalent (Direct Substitution): Parts that match all critical electrical parameters and package specifications. The BAS45A,143 is a parametric equivalent manufactured by the same supplier (Nexperia USA Inc.) with identical voltage rating (125 V), current rating (250 mA), forward voltage (1 V @ 100 mA), reverse recovery time (1.5 µs), and package type (DO-34). This part provides direct interchangeability without circuit redesign.

Similar Parts (Application-Dependent Substitution): Parts that maintain the same voltage rating (125 V) and through-hole mounting type but differ in current rating, package size, or recovery characteristics. These include BAY72TR, BAY73, FDH444, and FDH444TR. Substitution of these parts requires verification that the application circuit can accommodate the specified differences in current handling, package dimensions, or switching characteristics.

Key Parameters Determining Substitution:

Voltage - DC Reverse (Vr) (Max): Must equal or exceed 125 V
Current - Average Rectified (Io): Must equal or exceed 250 mA for direct substitution
Package / Case: DO-34 or DO-35 axial through-hole packages
Mounting Type: Through Hole
Operating Temperature - Junction: Must support 175°C maximum

Parameter Comparison

Parameter	BAS45A,133	BAS45A,143	BAY72TR	BAY73	FDH444	FDH444TR
Manufacturer	Nexperia USA Inc.	Nexperia USA Inc.	Fairchild Semiconductor	onsemi	Fairchild Semiconductor	Fairchild Semiconductor
Voltage - DC Reverse (Vr) (Max)	125 V	125 V	125 V	125 V	125 V	125 V
Current - Average Rectified (Io)	250 mA	250 mA	200 mA	500 mA	200 mA	200 mA
Voltage - Forward (Vf) (Max) @ If	1 V @ 100 mA	1 V @ 100 mA	1 V @ 100 mA	1 V @ 200 mA	1.2 V @ 300 mA	1.2 V @ 300 mA
Reverse Recovery Time (trr)	1.5 µs	1.5 µs	50 ns	1 µs	60 ns	60 ns
Current - Reverse Leakage @ Vr	1 nA @ 125 V	1 nA @ 125 V	100 nA @ 100 V	5 nA @ 100 V	50 nA @ 100 V	50 nA @ 100 V
Capacitance @ Vr, F	4 pF @ 0V, 1MHz	4 pF @ 0V, 1MHz	5 pF @ 0V, 1MHz	8 pF @ 0V, 1MHz	2.5 pF @ 0V, 1MHz	2.5 pF @ 0V, 1MHz
Package / Case	DO-204AG, DO-34, Axial	DO-204AG, DO-34, Axial	DO-204AH, DO-35, Axial	DO-204AH, DO-35, Axial	DO-204AH, DO-35, Axial	DO-204AH, DO-35, Axial
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Operating Temperature - Junction (Max)	175°C	175°C	175°C	175°C	175°C	175°C
Product Status	Active	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Not Specified	ROHS3 Compliant	Not Specified	Not Specified

Engineering Selection Recommendations

BAS45A,143 (Nexperia USA Inc.): This part is the recommended direct substitute for BAS45A,133. Both parts are manufactured by Nexperia USA Inc., share identical electrical specifications (125 V, 250 mA, 1 V @ 100 mA forward voltage, 1.5 µs recovery time), and use the same DO-34 package. Both are ROHS3 compliant and Active product status. Selection of BAS45A,143 requires no circuit modification and provides equivalent performance.

BAY73 (onsemi): This part is suitable for applications requiring higher current capacity (500 mA versus 250 mA). The 125 V voltage rating and through-hole mounting are maintained. The reverse recovery time is 1 µs (faster than BAS45A,133 at 1.5 µs), and reverse leakage is 5 nA @ 100 V. The package is DO-35 (larger than DO-34), which may require PCB layout adjustment. ROHS3 compliance and Active product status are confirmed. Selection is appropriate when circuit design permits the larger package footprint and higher current capacity.

BAY72TR (Fairchild Semiconductor): This part is suitable for applications with reduced current requirements (200 mA versus 250 mA). The 125 V voltage rating and through-hole mounting are maintained. The reverse recovery time is 50 ns (significantly faster than BAS45A,133), indicating small-signal switching characteristics. The package is DO-35. Reverse leakage is 100 nA @ 100 V, which is higher than the main part. Selection is appropriate for low-current applications where faster switching is beneficial.

FDH444 and FDH444TR (Fairchild Semiconductor): These parts are functionally identical to each other and suitable for applications with reduced current requirements (200 mA versus 250 mA). The 125 V voltage rating and through-hole mounting are maintained. Forward voltage is 1.2 V @ 300 mA (higher than BAS45A,133 at 1 V @ 100 mA). Reverse recovery time is 60 ns (faster than BAS45A,133). The package is DO-35. Selection is appropriate for low-current applications where faster switching and smaller junction capacitance (2.5 pF) are beneficial.

Frequently Asked Questions (FAQ)

Q: Can BAS45A,143 be used as a direct replacement for BAS45A,133?

A: Yes. BAS45A,143 is a parametric equivalent with identical voltage rating (125 V), current rating (250 mA), forward voltage (1 V @ 100 mA), reverse recovery time (1.5 µs), and DO-34 package. No circuit modification is required.

Q: What is the difference between DO-34 and DO-35 packages?

A: DO-34 and DO-35 are both axial through-hole diode packages with different physical dimensions. DO-34 is smaller than DO-35. Substitution from DO-34 to DO-35 requires verification that the PCB layout and component spacing accommodate the larger package size.

Q: Can BAY73 replace BAS45A,133 in all applications?

A: BAY73 has a higher current rating (500 mA versus 250 mA) and uses a DO-35 package instead of DO-34. The voltage rating (125 V) is identical. Substitution is appropriate when the circuit design permits the larger package footprint and higher current capacity. The faster reverse recovery time (1 µs versus 1.5 µs) may affect switching behavior in time-sensitive applications.

Q: What are the advantages of FDH444 or FDH444TR over BAS45A,133?

A: FDH444 and FDH444TR have faster reverse recovery time (60 ns versus 1.5 µs) and lower junction capacitance (2.5 pF versus 4 pF). These characteristics are beneficial for high-frequency switching applications. However, the current rating is lower (200 mA versus 250 mA), and forward voltage is higher (1.2 V @ 300 mA versus 1 V @ 100 mA).

Q: Are all substitute parts ROHS3 compliant?

A: BAS45A,143 and BAY73 are confirmed ROHS3 compliant. RoHS compliance status is not specified for BAY72TR, FDH444, and FDH444TR in the provided data. Verification with the manufacturer is required if ROHS3 compliance is a design requirement.

Q: What is the significance of reverse recovery time in diode selection?

A: Reverse recovery time (trr) determines how quickly a diode transitions from conducting to blocking state. Shorter recovery times (50–60 ns for FDH444/BAY72TR) are beneficial for high-frequency switching applications. Longer recovery times (1–1.5 µs for BAS45A,133/BAY73) are typical for general-purpose rectification. Selection depends on circuit switching frequency and performance requirements.

Q: Can I use a substitute part with lower current rating than BAS45A,133?

A: Substitution with lower current rating (BAY72TR, FDH444, FDH444TR at 200 mA versus 250 mA) is permissible only if the circuit design ensures that the actual operating current does not exceed the substitute part's rating. Exceeding the rated current causes excessive heat generation and component failure.

Q: What is the impact of higher reverse leakage current?

A: Higher reverse leakage current (100 nA for BAY72TR versus 1 nA for BAS45A,133) increases power dissipation in the reverse-biased state and may affect circuit performance in precision analog applications. For general-purpose rectification, this difference is typically negligible.

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