Diodes Incorporated ZTX560STZ

Overview

ZTX560STZ from Diodes Incorporated (formerly Zetex Semiconductors) is a PNP silicon planar high-voltage transistor rated for V_CEO = −500 V, V_CBO = −500 V, and continuous I_C = −150 mA, with low V_CE(sat) of −0.2 V at I_C = −20 mA / I_B = −2 mA, used in high-voltage switching and flyback converter primary-side control circuits.

For engineers reviewing the ZTX560STZ datasheet, ZTX560STZ pinout, ZTX560STZ application, or ZTX560STZ equivalent, key selection criteria include verified high-voltage blocking capability, h_FE stability up to −50 mA, pulsed I_CM rating of −500 mA, thermal robustness to +150°C, and TO-92 compatible leadform for legacy industrial power designs.

Technical Context

This PNP bipolar junction transistor operates in common-emitter configuration with guaranteed breakdown across collector-base (−500 V) and collector-emitter (−500 V) under specified test conditions, supporting high-side switching in offline SMPS and relay drivers where negative rail control is required.

Its f_T of 60 MHz and C_obo of 8 pF at V_CB = −20 V enable fast turn-on/turn-off transitions (t_on = 110 ns typ., t_off = 1.5 µs typ.) under −100 V V_CE, −50 mA I_C, and ±5/10 mA base drive, meeting timing demands of quasi-resonant converters.

Key Specifications

Pinout & Package

Supplied in TO-92 plastic package (E-LINE outline), with standard three-terminal configuration: emitter, base, and collector arranged in linear pin order (viewed from flat side, leads down).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZTX560STZ, ZTX550STZ trades 100 V blocking margin for reduced cost and similar gain linearity, while MJD2955G offers vastly higher power dissipation but cannot replace it in high-voltage flyback or relay driver roles due to its −70 V V_CEO.

Availability

ZTX560STZ is available at Aetrix Electronics and suitable for industrial flyback converters, AC-DC adapter primary switches, and relay drivers requiring stable component supply and long-term obsolescence management.

Supply support for ZTX560STZ 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 acquired Zetex Semiconductors in 2008 and maintains its portfolio of high-reliability discrete semiconductors for industrial and automotive markets.

The ZTX series was designed specifically for high-voltage, medium-current switching applications in legacy and cost-sensitive power conversion systems where TO-92 packaging and proven bipolar performance are critical.

FAQ

What is the maximum safe operating voltage for ZTX560STZ in continuous DC mode?

The ZTX560STZ is rated for continuous V_CEO = −500 V and V_CBO = −500 V at T_j ≤ +150°C. Operation above −450 V DC requires derating per manufacturer's thermal curves and must maintain junction temperature below limit using appropriate PCB copper area or heatsinking.

Can ZTX560STZ be used in avalanche mode?

No-ZTX560STZ is not characterized or rated for repetitive avalanche operation. Its absolute maximum ratings define safe non-avalanche operation only. Intentional avalanche use may cause parametric shift or catastrophic failure due to lack of energy-rated SOA data in the datasheet.

Is ZTX560STZ RoHS compliant and halogen-free?

Yes-ZTX560STZ meets RoHS Directive 2011/65/EU and is halogen-free per IEC 61249-2-21. The TO-92 package uses lead-free matte tin plating on leads and complies with Diodes Incorporated's PPAP documentation for industrial-grade shipments.

What is the recommended base resistor value for driving ZTX560STZ with a 3.3 V MCU GPIO?

For saturation at I_C = −50 mA, h_FE ≥ 100 requires I_B ≥ −0.5 mA. With V_BE(sat) ≈ −0.9 V and 3.3 V GPIO, R_B = (3.3 V − 0.9 V) / 0.5 mA = 4.8 kΩ. Use 4.7 kΩ ±5% standard value; verify actual V_CE(sat) under load and temperature.