DDZ39ASF-7 Equivalent & Substitute Parts

Part Overview

The DDZ39ASF-7 is an active Zener diode manufactured by Diodes Incorporated, rated at 35.58 V nominal with 500 mW power dissipation in a surface mount SOD-323F package. This component is ROHS3 compliant and carries MSL 1 (Unlimited) moisture sensitivity classification. Substitute parts are identified based on matching electrical performance within specified tolerance bands and compatible mechanical packaging for direct circuit board replacement.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	35.58	V
Tolerance	±3%	%
Power - Max	500	mW
Impedance (Max)	85	Ohms
Current - Reverse Leakage @ Vr	200	nA @ 30 V
Voltage - Forward (Vf) (Max) @ If	900	mV @ 10 mA
Operating Temperature Range	-65 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	SOD-323F	—
RoHS Status	ROHS3 Compliant	—
MSL Rating	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution eligibility for the DDZ39ASF-7 is determined by the following criteria:

Primary Matching Parameters:

Zener voltage nominal within ±6% of 35.58 V (acceptable range: 33.4 V to 37.8 V)
Power dissipation rating of 200 mW or greater
Surface mount package compatibility (SOD-323 or SOD-323F)
Operating temperature range encompassing -65°C to 150°C or compatible subset
ROHS3 compliance and MSL 1 classification

Secondary Compatibility Factors:

Impedance (Zzt) specification within 70 to 90 Ohms
Reverse leakage current at specified voltage reference
Forward voltage characteristics at rated current

The identified substitute parts meet these criteria through parametric equivalence or manufacturer-recommended cross-reference designation.

Parameter Comparison

Parameter	DDZ39ASF-7 (Main)	BZT52C36S-TP	MMXZ5258B-TP
Manufacturer	Diodes Incorporated	Micro Commercial Co	Micro Commercial Co
Voltage - Zener (Nom)	35.58 V	36 V	36 V
Tolerance	±3%	±6%	±5%
Power - Max	500 mW	200 mW	200 mW
Impedance (Max)	85 Ohms	90 Ohms	70 Ohms
Current - Reverse Leakage @ Vr	200 nA @ 30 V	100 nA @ 25.2 V	100 nA @ 27 V
Voltage - Forward (Vf) (Max) @ If	900 mV @ 10 mA	900 mV @ 10 mA	1.2 V @ 100 mA
Operating Temperature Range	-65 to 150°C	-65 to 150°C	-55 to 150°C
Package / Case	SOD-323F	SOD-323	SOD-323
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

DDZ39ASF-7 (Diodes Incorporated) Primary selection when original part availability and exact parametric matching are required. Offers 500 mW power rating and ±3% tolerance. ROHS3 compliant with MSL 1 classification. Operating temperature range -65°C to 150°C. Current inventory: 881 pieces.

BZT52C36S-TP (Micro Commercial Co) Manufacturer-recommended substitute with 36 V nominal zener voltage (1.2% deviation from main part). Reduced power rating of 200 mW requires circuit design verification for applications exceeding this threshold. ±6% tolerance specification. Impedance 90 Ohms. ROHS3 compliant with MSL 1 classification. Operating temperature range -65°C to 150°C. Current inventory: 3824 pieces.

MMXZ5258B-TP (Micro Commercial Co) Manufacturer-recommended substitute with 36 V nominal zener voltage (1.2% deviation from main part). Reduced power rating of 200 mW requires circuit design verification for applications exceeding this threshold. ±5% tolerance specification. Impedance 70 Ohms. ROHS3 compliant with MSL 1 classification. Operating temperature range -55°C to 150°C (lower minimum temperature limit). Current inventory: 3670 pieces.

All substitute parts maintain SOD-323 package compatibility with SOD-323F footprints and carry identical regulatory compliance certifications.

Frequently Asked Questions (FAQ)

Q: Can BZT52C36S-TP or MMXZ5258B-TP replace DDZ39ASF-7 in all applications?

A: Substitution is valid when circuit design accommodates the reduced 200 mW power rating compared to the original 500 mW specification. Zener voltage deviation of 1.2% (36 V vs. 35.58 V) falls within acceptable tolerance bands for most voltage regulation applications. Verify circuit current and power dissipation requirements before substitution.

Q: What is the difference between SOD-323 and SOD-323F packages?

A: Both packages are mechanically compatible for surface mount PCB placement. SOD-323F is a variant designation. Footprint compatibility is maintained across both package types for direct substitution.

Q: Does the ±6% tolerance of BZT52C36S-TP affect circuit performance compared to ±3% of DDZ39ASF-7?

A: Tolerance specification defines the manufacturing variation band around the nominal zener voltage. Wider tolerance (±6%) permits greater voltage deviation within specification limits. Circuit design must accommodate the full tolerance range of the selected component. For precision voltage regulation, the ±3% tolerance of DDZ39ASF-7 provides tighter control.

Q: Are there temperature range limitations with MMXZ5258B-TP?

A: MMXZ5258B-TP operates from -55°C to 150°C, compared to -65°C to 150°C for DDZ39ASF-7. Applications requiring operation below -55°C require the original part or BZT52C36S-TP.

Q: What is the significance of impedance (Zzt) differences between parts?

A: Impedance specification defines dynamic resistance characteristics at the zener operating point. Lower impedance (70 Ohms for MMXZ5258B-TP) provides better voltage regulation stability under load transients compared to higher impedance (85 Ohms for DDZ39ASF-7). Impedance differences of this magnitude are typically transparent to circuit operation in standard voltage regulation applications.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. DDZ39ASF-7, BZT52C36S-TP, and MMXZ5258B-TP are all ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity classification, enabling direct substitution from a regulatory and environmental standpoint.

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