Diodes Incorporated ZTX553STOA

Overview

ZTX553STOA from Zetex Semiconductors (now Diodes Incorporated) is a PNP silicon planar medium-power bipolar junction transistor designed for linear amplification and switching in industrial power control circuits. It features -100 V V_CEO, -1 A continuous collector current, 1 W power dissipation at 25°C, and operates across -55°C to +200°C junction temperature range - used in DC-DC converter feedback stages and relay drivers.

For engineers reviewing the ZTX553STOA datasheet, ZTX553STOA pinout, ZTX553STOA application, or ZTX553STOA equivalent, key selection criteria include verified V_CEO(sus) = -100 V, h_FE = 40–200 at I_C = -150 mA / -1 A, f_T = 150 MHz, V_CE(sat) ≤ -0.25 V, and TO-92 compatible E-Line package thermal performance.

Technical Context

This PNP BJT operates with fixed-base or emitter-follower biasing in medium-voltage analog and switching applications. Its -120 V V_CBO and -100 V V_CEO(sus) support robust operation in 80–100 V rail systems, while the 150 MHz f_T enables stable gain up to audio frequencies and fast switching with t_r/t_f < 100 ns under pulsed conditions.

The device exhibits low saturation voltages: V_CE(sat) = -0.25 V at I_C = -150 mA / I_B = -15 mA and V_BE(sat) = -1.1 V under same conditions. C_obo = 12 pF at V_CB = -10 V ensures predictable high-frequency output impedance behavior.

Key Specifications

Pinout & Package

Supplied in an E-Line TO-92 compatible plastic package with standard lead configuration and JEDEC TO-92 thermal profile. Mounting via PCB through-hole with 0.1" pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD2955G and BC807-40, ZTX553STOA uniquely balances TO-92 manufacturability, -100 V ruggedness, and 150 MHz bandwidth - making it optimal for cost-sensitive, medium-voltage industrial signal conditioning where thermal mass and layout flexibility matter.

Availability

ZTX553STOA is available at Aetrix Electronics and suitable for industrial relay drivers, DC-DC converter bias networks, and overvoltage protection circuits requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for ZTX553STOA 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

Zetex Semiconductors was a UK-based analog and discrete semiconductor specialist acquired by Diodes Incorporated in 2008, known for high-reliability transistors and diodes targeting industrial and automotive markets.

The ZTX series was engineered for ruggedized medium-power linear and switching applications - emphasizing high breakdown voltage, wide temperature operation, and TO-92 compatibility for legacy system upgrades.

FAQ

What is the maximum safe continuous collector current for ZTX553STOA?

The absolute maximum continuous collector current is -1 A at T_amb = 25°C with adequate PCB copper area. Derating is required above 25°C: 5.7 mW/°C reduction in P_tot implies usable I_C drops to ~−650 mA at 75°C ambient with standard FR-4 board layout and no heatsink.

Does ZTX553STOA support pulse operation beyond its DC ratings?

Yes - pulsed operation is specified with I_CM = -2 A (peak), duty cycle ≤2%, and pulse width ≤300 µs. This enables short-duration surge handling in protection circuits and snubberless relay driving, provided average power remains within 1 W thermal limit.

Can ZTX553STOA replace ZTX552 in existing designs?

Yes - ZTX553STOA is a direct upgrade with identical pinout and package, offering improved -120 V V_CBO and -100 V V_CEO(sus) versus ZTX552's -100 V and -80 V. All other electrical parameters match or exceed ZTX552, enabling drop-in reliability enhancement without layout change.

Is ZTX553STOA RoHS compliant and halogen-free?

Yes - as part of Diodes Incorporated's post-acquisition product line, ZTX553STOA meets RoHS Directive 2011/65/EU and is certified halogen-free per IEC 61249-2-21. Full compliance documentation is available under Diodes' QM-001 material declaration system.