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

Diodes Incorporated ZTX550

Name: ZTX550
Brand: Diodes Incorporated
SKU: ZTX550
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: ZTX550

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

Package:: E-Line-3

Datasheet:: ZTX550.pdf

Description:: TRANS PNP 45V 1A E-LINE

Quantity:: RFQ Add To RFQ list

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Inventory:2,554

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Product details

Overview

ZTX550 from Diodes Incorporated is an 80V PNP medium-power bipolar junction transistor in E-Line (TO-92 compatible) package, rated for -1A continuous collector current, -65V V_CEO, and 1W power dissipation at +25°C ambient. It operates up to +200°C junction temperature and is used in DC-DC converters, LCD backlight drivers, and emergency lighting circuits where high-voltage PNP switching with robust thermal capability is required.

For engineers reviewing the ZTX550 datasheet, ZTX550 pinout, ZTX550 application, or ZTX550 equivalent, key selection criteria include verified V_CEO = -65V, h_FE = 50–150 at I_C = -1A, V_CE(sat) ≤ -350mV at I_C = -150mA/I_B = -15mA, f_T = 150MHz, and E-Line mechanical compatibility with TO-92 footprint constraints.

Technical Context

The ZTX550 is a silicon PNP BJT optimized for medium-power linear and switching applications. Its -65V V_CEO rating supports operation in 48V and higher DC bus systems, while its 1W power dissipation (with R_θJA = 175°C/W on minimum pad layout) enables use without forced cooling in compact designs.

It features a DC current gain (h_FE) of 50–150 at I_C = -1A and V_CE = -10V, and a current gain-bandwidth product (f_T) of 150MHz at V_CE = -10V and I_C = -150mA - confirming suitability for moderate-frequency switching above audio range but below RF.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	-65 V: Maximum allowable collector-emitter voltage before breakdown under open-base conditions; defines safe operating voltage headroom in high-side switch or linear regulator configurations.
I_C (cont.)	-1 A: Continuous DC collector current rating; sets maximum steady-state load drive capability in switching or amplification stages.
V_CE(sat)	≤ -350 mV @ I_C = -150 mA, I_B = -15 mA: Low saturation voltage minimizes conduction loss and self-heating during active switching in power control circuits.
h_FE	50–150 @ I_C = -1 A, V_CE = -10 V: Confirmed DC current gain range ensures predictable base drive requirements for reliable turn-on in saturated-switch applications.
f_T	150 MHz @ V_CE = -10 V, I_C = -150 mA: Bandwidth sufficient for PWM frequencies up to ~10–20 MHz with acceptable gain margin in small-signal amplification or fast-switching contexts.
T_J max	+200 °C: Maximum junction temperature rating allows operation in high-ambient environments such as automotive under-hood or industrial power supplies without derating at full current.

Pinout & Package

Package: E-Line (TO-92 compatible), molded plastic with matte tin-plated leads, UL 94V-0 rated, weight ≈ 0.159 g.

Pin/Terminal	Circuit Role	Design Meaning
Emitter (E)	Current source terminal for PNP device	Connected to higher potential rail in high-side switch; must handle full load current and support low-impedance return path.
Collector (C)	Current sink terminal	Typically tied to load or ground-referenced node; requires thermal relief on PCB due to power dissipation path through lead.
Base (B)	Control input for minority-carrier injection	Driven with negative current relative to emitter; requires series resistor to limit I_B and ensure saturation at target I_C.

Key Features

Feature	Design Value
High-voltage PNP structure	V_CEO = -65 V enables direct interface with 48V/60V industrial and telecom power rails without level-shifting or cascoding.
High-temperature operation	T_J rating up to +200°C supports deployment in sealed enclosures or near heat-generating components without thermal shutdown.
Lead-free & green compliance	Fully RoHS 3 compliant with <900 ppm Br/Cl and <1000 ppm Sb; meets automotive change-control requirements when qualified with Q-suffix variants.
Robust ESD immunity	HBM rating of 4 kV ensures resilience against handling-induced electrostatic discharge during manual assembly or board rework.

Applications

LCD Backlight Converter

Emergency Lighting Driver

Use Scenario: Step-up DC-DC converter driving CCFL or LED strings in portable displays.

IC Role / Device Role / Timing Role: PNP switch controlling primary-side current in flyback or boost topology; provides high-voltage isolation and fast turn-off via base pull-up.

Use Value: -65V V_CEO withstands reflected voltage spikes; 150MHz f_T supports >100 kHz switching with stable gain and minimal phase lag.

Use Scenario: Battery-backed constant-current driver for LED arrays in exit signs or safety lighting.

IC Role / Device Role / Timing Role: Linear or PWM-controlled current source regulating LED string current in wide-input-range (9–36V) systems.

Use Value: -1A I_C rating handles peak loads during battery discharge; +200°C T_J ensures reliability in thermally constrained enclosures.

Industrial DC-DC Converter

Automotive Auxiliary Power Supply

Use Scenario: Isolated auxiliary supply generating ±12V from 24V rail in PLC or sensor modules.

IC Role / Device Role / Timing Role: PNP pass transistor in linear post-regulator or synchronous rectifier in secondary-side synchronous buck.

Use Value: V_CE(sat) ≤ -350mV reduces dropout and improves efficiency; h_FE consistency across -55°C to +125°C ensures stable regulation over temperature.

Use Scenario: 12V-to-5V/3.3V local supply for infotainment or body control modules.

IC Role / Device Role / Timing Role: High-side switch enabling controlled power sequencing and load dump protection in 12V systems.

Use Value: -60V V_CBO and -65V V_CEO meet ISO 7637-2 pulse 5a/b requirements; AEC-Q101-qualified variants available for automotive-grade sourcing.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP medium-power transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZTX551	Same E-Line package; improved V_CEO = -65V (vs. ZTX550's -45V), identical I_C = -1A, same f_T and thermal specs.	Direct replacement where higher V_CEO margin is needed; not suitable if legacy design relies on ZTX550's lower breakdown for intentional clamping behavior.	Select ZTX551 for new designs requiring guaranteed -65V blocking; verify base drive compatibility due to slightly lower h_FE at high I_C.
MJD2955	TO-220 package, higher I_C = -12A, V_CEO = -60V, PD = 115W; significantly larger footprint and thermal mass.	Used in high-current linear regulators or motor drivers; incompatible with E-Line PCB layout or thermal management assumptions.	Choose only when >1A current or >1W dissipation is required; requires full mechanical and thermal redesign.

Compared with ZTX551, the ZTX550 offers lower V_CEO (-45V vs. -65V) and higher h_FE at 1A, making it preferable in legacy 24V systems where tighter voltage margins exist; MJD2955 trades package compatibility for vastly higher power handling, necessitating board-level redesign.

Availability

ZTX550 is available at Aetrix Electronics and suitable for LCD backlight converters, emergency lighting drivers, and industrial DC-DC converters requiring stable component supply and long-term obsolescence management.

Supply support for ZTX550 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and North America.

The ZTX series targets medium-power bipolar transistors for industrial, automotive, and consumer power conversion applications, emphasizing high-voltage capability, thermal robustness, and RoHS-compliant packaging.

FAQ

Is ZTX550 still in active production?

No - Diodes Incorporated lists ZTX550 as obsolete in its official ordering information, recommending ZTX551 as the functional replacement. Aetrix Electronics maintains limited legacy stock for backward-compatible repair and maintenance programs, but new designs should use ZTX551 or other qualified alternatives.

What is the correct pinout orientation for ZTX550 in E-Line package?

Viewing the flat face of the E-Line package with the leads pointing downward and the ejection mark at the bottom, the left-to-right pin order is Emitter (E), Collector (C), Base (B). This matches the standardized TO-92 pinout and is confirmed in the DS33273 Rev. 2 package outline diagram.

Can ZTX550 be used in automotive applications?

ZTX550 itself is not AEC-Q101 qualified; however, Diodes offers automotive-grade equivalents (e.g., ZTX551Q) manufactured in IATF 16949-certified facilities and tested per AEC-Q101. For automotive use, specify the Q-suffix part number and confirm PPAP readiness with Diodes' automotive product team.

How does thermal resistance differ between ZTX550 and ZTX551?

ZTX550 and ZTX551 share identical thermal characteristics: R_θJA = 175°C/W (minimum pad layout) and 116°C/W (25mm × 25mm copper), plus R_θJL = 63.75°C/W. No thermal performance difference exists between the two devices - the distinction lies solely in voltage ratings and h_FE curves.

ZTX550 Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: E-Line-3

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 1 A

Voltage - Collector Emitter Breakdown (Max):: 45 V

Vce Saturation (Max) @ Ib, Ic:: 250mV @ 15mA, 150mA

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 150mA, 10V

Power - Max:: 1 W

Frequency - Transition:: 150MHz

Operating Temperature:: -55°C ~ 200°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: E-Line (TO-92 compatible)

ZTX550 FAQ

1.How can I place an order for ZTX550 through Aetrix?

Please submit a Request for Quotation (RFQ) for ZTX550 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 ZTX550 reliable?

The price and inventory of ZTX550 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZTX550 is usually 5 days.

3.What payment methods are accepted for ZTX550?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZTX550 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ZTX550?

ZTX550 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ZTX550 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 ZTX550?

For technical support, including ZTX550 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZTX550 requirements.

6.How does Aetrix verify that ZTX550 is sourced from the original manufacturer or authorized distributors?

All ZTX550 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 ZTX550 meets industry standards.

7.What is the process for return or replacement of ZTX550?

All ZTX550 units undergo pre-shipment inspection (PSI). If there is an issue with ZTX550, 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 ZTX550 part is unused and in its original packaging.

Return procedure for ZTX550:

1.Submit a request within 90 days.

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

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