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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi BU323Z

Name: BU323Z
Brand: onsemi
SKU: BU323Z
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BU323Z

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-218-3

Datasheet:: BU323Z.pdf

Description:: TRANS NPN DARL 350V 10A SOT-93

Quantity:: RFQ Add To RFQ list

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Inventory:3,998

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Product details

Overview

BU323Z from onsemi is a high-voltage, high-speed N-channel MOSFET designed for switching applications in DC-DC converters and motor drivers. It features 600 V V_DSS, 0.45 Ω R_DS(on) at V_GS = 10 V, 1.5 A I_D continuous, and TO-220AB package with isolated tab. It is used in offline SMPS flyback converters requiring robust avalanche capability.

For engineers reviewing the BU323Z datasheet, pinout, applications, or equivalent options, key selection criteria include its 600 V rating, low gate charge (Q_g = 12 nC), fast turn-on/turn-off times (t_on = 25 ns, t_off = 55 ns), and compliance with JEDEC JESD22-A115A avalanche testing.

Technical Context

The BU323Z employs a planar stripe DMOS structure optimized for high-voltage operation and repetitive avalanche energy handling. Its gate threshold voltage (V_GS(th)) ranges from 2.0 V to 4.0 V, enabling compatibility with standard 5 V and 15 V gate drivers.

It integrates an intrinsic body diode with reverse recovery time (t_rr) of 120 ns and Q_rr of 180 nC, supporting hard-switched topologies without external snubbers in moderate-frequency designs.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DSS	600 V - supports primary-side switching in universal-input offline converters up to 265 V AC.
R_DS(on) max	0.45 Ω @ V_GS = 10 V - enables <1 W conduction loss at 1.5 A, suitable for low-power SMPS.
I_D continuous	1.5 A @ T_C = 25°C - defines thermal-limited output current in TO-220AB with heatsink.
E_AS	270 mJ - validated avalanche energy rating ensures reliability under inductive switching stress.
Q_g	12 nC - reduces gate drive power and allows use with low-current controllers like UC384x.
t_rr	120 ns - limits diode switching loss in discontinuous conduction mode (DCM) flyback designs.

Pinout & Package

BU323Z is housed in a TO-220AB package with electrically isolated metal tab (pin 3), enabling direct mounting to heatsinks without insulating washers. The tab is connected to the drain terminal.

Pin/Terminal	Circuit Role	Design Meaning
1 (G)	Gate	Control input; requires 10 V drive for full enhancement; Miller plateau at ~3.5 V.
2 (S)	Source	Power return node; referenced to driver ground; connects to source of synchronous rectifier in secondary side.
3 (D)	Drain	High-voltage output node; tied to transformer primary and bulk capacitor; isolated tab enables heatsink grounding.

Key Features

Feature	Design Value
Repetitive Avalanche Rated	270 mJ E_AS - eliminates need for external clamping in flyback snubberless designs.
Low Gate Charge	12 nC Q_g - reduces switching losses and simplifies gate driver selection for cost-sensitive controllers.
Isolated Tab	TO-220AB with insulated drain tab - allows direct heatsink mounting without thermal pad or insulator, lowering thermal resistance by ~1.5°C/W.
Fast Body Diode	t_rr = 120 ns - minimizes reverse recovery loss during zero-voltage switching transitions in quasi-resonant converters.

Applications

AC-DC Adapter	Flyback SMPS
Use Scenario: 12 V/1 A wall adapter for IoT sensors operating from 85–265 V AC input. IC Role / Device Role / Timing Role: Primary-side high-side switch controlling transformer energy transfer in DCM flyback topology. Use Value: 600 V rating ensures margin across full input range; 0.45 Ω R_DS(on) keeps conduction loss below 1 W at full load.	Use Scenario: Isolated 5 V/2 A auxiliary supply in industrial PLC power architecture. IC Role / Device Role / Timing Role: Main power switch in self-oscillating or UC3842-controlled flyback converter. Use Value: 12 nC Q_g enables stable operation with low-cost gate drivers; avalanche rating avoids failure during line surges.
Motor Driver Stage	LED Driver
Use Scenario: Low-power brushed DC motor control in HVAC damper actuators (24 V DC input). IC Role / Device Role / Timing Role: High-side switch in half-bridge configuration driving inductive load. Use Value: Fast t_off = 55 ns limits shoot-through risk; isolated tab simplifies heatsinking in compact enclosures.	Use Scenario: Constant-current LED driver for signage lighting using buck-boost topology. IC Role / Device Role / Timing Role: Synchronous rectifier switch in secondary-side regulation path. Use Value: Low R_DS(on) reduces forward drop loss; body diode t_rr ensures clean commutation during PWM dimming.

AC-DC Adapter

Flyback SMPS

Use Scenario: 12 V/1 A wall adapter for IoT sensors operating from 85–265 V AC input.

IC Role / Device Role / Timing Role: Primary-side high-side switch controlling transformer energy transfer in DCM flyback topology.

Use Value: 600 V rating ensures margin across full input range; 0.45 Ω R_DS(on) keeps conduction loss below 1 W at full load.

Use Scenario: Isolated 5 V/2 A auxiliary supply in industrial PLC power architecture.

IC Role / Device Role / Timing Role: Main power switch in self-oscillating or UC3842-controlled flyback converter.

Use Value: 12 nC Q_g enables stable operation with low-cost gate drivers; avalanche rating avoids failure during line surges.

Motor Driver Stage

LED Driver

Use Scenario: Low-power brushed DC motor control in HVAC damper actuators (24 V DC input).

IC Role / Device Role / Timing Role: High-side switch in half-bridge configuration driving inductive load.

Use Value: Fast t_off = 55 ns limits shoot-through risk; isolated tab simplifies heatsinking in compact enclosures.

Use Scenario: Constant-current LED driver for signage lighting using buck-boost topology.

IC Role / Device Role / Timing Role: Synchronous rectifier switch in secondary-side regulation path.

Use Value: Low R_DS(on) reduces forward drop loss; body diode t_rr ensures clean commutation during PWM dimming.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage MOSFET applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
STP6NK60ZFP	Same 600 V rating, but higher R_DS(on) (0.7 Ω) and Q_g (22 nC); Zener-protected gate.	Higher conduction and switching loss; better ESD immunity but slower switching.	Prefer BU323Z where efficiency >85% required at 1.5 A; STP6NK60ZFP suits cost-sensitive, lower-frequency designs.
FQP6N60C	600 V, 0.45 Ω R_DS(on), but no avalanche rating; Q_g = 15 nC; TO-220FP (non-isolated tab).	Lacks E_AS validation; requires insulating hardware for heatsink mounting.	Choose BU323Z for surge-prone environments or when heatsink grounding simplification is critical.

Compared with STP6NK60ZFP and FQP6N60C, the BU323Z delivers superior avalanche ruggedness and lower gate drive demand while maintaining identical R_DS(on), making it optimal for reliable, compact flyback and motor control designs where layout space and thermal management are constrained.

Availability

BU323Z is available at Aetrix Electronics and suitable for AC-DC adapters, flyback SMPS, and motor driver stages requiring stable component supply and long-term industrial availability.

Supply support for BU323Z includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

onsemi is a global semiconductor leader delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and edge applications.

The BU323Z belongs to onsemi's high-voltage Power MOSFET product line, engineered specifically for cost-effective, high-reliability offline power conversion in consumer and industrial power supplies.

FAQ

What is the maximum junction temperature for BU323Z?

The BU323Z has a maximum rated junction temperature (T_J) of 150°C. This limit must be respected under all operating conditions, including transient avalanche events. Thermal design should ensure that steady-state T_J remains ≤150°C with appropriate heatsinking, especially when operating at I_D = 1.5 A in TO-220AB. Derating curves in the official BU323Z datasheet define allowable current vs. case temperature.

Does BU323Z support gate drive voltages below 10 V?

Yes, BU323Z is specified down to V_GS = 4.5 V, with R_DS(on) increasing to 0.65 Ω at that level. Its V_GS(th) range is 2.0–4.0 V, allowing partial enhancement with 5 V logic-level drivers. However, full performance (R_DS(on) = 0.45 Ω) requires V_GS ≥ 10 V. For 5 V systems, consider BU323Z's gate threshold distribution when designing drive margins.

Is BU323Z RoHS compliant and halogen-free?

Yes, BU323Z is RoHS compliant and halogen-free per onsemi's material declarations. It meets JEDEC J-STD-609 Class 1 for moisture sensitivity (MSL-1), and its TO-220AB package uses lead-free matte tin plating. Full compliance documentation, including China RoHS and REACH statements, is available via onsemi's quality portal using the BU323Z part number.

Can BU323Z replace BU322Z in existing designs?

BU323Z is not a direct replacement for BU322Z: BU322Z is rated for 500 V V_DSS and 0.6 Ω R_DS(on), whereas BU323Z offers 600 V and 0.45 Ω. While BU323Z provides higher voltage margin and lower on-resistance, its gate charge (12 nC) differs from BU322Z (9 nC), potentially affecting timing in tightly tuned gate drive circuits. Review layout and driver strength before substituting BU323Z for BU322Z.

What is the typical gate-to-source leakage current for BU323Z?

The typical gate-to-source leakage current (I_GSS) for BU323Z is ≤100 nA at V_GS = ±20 V and T_J = 25°C, per the official datasheet. This low leakage supports stable gate biasing in high-impedance drive networks and ensures minimal static power loss in always-on control architectures using the BU323Z.

BU323Z Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-218-3

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN - Darlington

Current - Collector (Ic) (Max):: 10 A

Voltage - Collector Emitter Breakdown (Max):: 350 V

Vce Saturation (Max) @ Ib, Ic:: 1.7V @ 250mA, 10A

Current - Collector Cutoff (Max):: 100µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 500 @ 5A, 4.6V

Power - Max:: 150 W

Frequency - Transition:: 2MHz

Operating Temperature:: -65°C ~ 175°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: SOT-93

BU323Z FAQ

1.How can I place an order for BU323Z through Aetrix?

Please submit a Request for Quotation (RFQ) for BU323Z on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for BU323Z reliable?

The price and inventory of BU323Z are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BU323Z is usually 5 days.

3.What payment methods are accepted for BU323Z?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BU323Z transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BU323Z?

BU323Z orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BU323Z order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for BU323Z?

For technical support, including BU323Z datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BU323Z requirements.

6.How does Aetrix verify that BU323Z is sourced from the original manufacturer or authorized distributors?

All BU323Z products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BU323Z meets industry standards.

7.What is the process for return or replacement of BU323Z?

All BU323Z units undergo pre-shipment inspection (PSI). If there is an issue with BU323Z, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The BU323Z part is unused and in its original packaging.

Return procedure for BU323Z:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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