Diodes Incorporated ZTX614QSTZ

Overview

ZTX614QSTZ from Diodes Incorporated is an NPN silicon planar medium-power Darlington transistor with V_CEO = 100 V, I_C = 800 mA continuous, h_FE = 10,000 at I_C = 500 mA, P_tot = 1.0 W, and TO-92 compatible E-line package; used in high-gain switching and linear amplification stages of industrial power supplies and relay drivers.

For engineers reviewing the ZTX614QSTZ datasheet, ZTX614QSTZ pinout, ZTX614QSTZ application, or ZTX614QSTZ equivalent, key selection criteria include verified Darlington gain linearity at 500 mA, V_CE(sat) ≤ 1.25 V under 8 mA base drive, thermal derating slope of 5.7 mW/°C, and E-line TO-92 mechanical compatibility with BCX38 footprint.

Technical Context

This Darlington pair integrates two NPN transistors monolithically to achieve high DC current gain while maintaining single-base control. It operates with a guaranteed minimum h_FE of 5000 at 100 mA and 10,000 at 500 mA, enabling low-base-drive switching in load-control circuits.

V_CEO(sus) = 100 V ensures robust operation under inductive load turn-off transients, and V_CE(sat) = 1.25 V at I_C = 800 mA / I_B = 8 mA confirms efficient conduction with minimal power loss in saturated switching mode.

Key Specifications

Pinout & Package

Package: E-line TO-92 compatible (3-lead plastic package, same outline and lead pitch as BCX38). Lead identification follows standard TO-92 orientation: viewed from flat side with leads down, left-to-right is Emitter (E), Base (B), Collector (C).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Darlington transistor applications.

Compared with BCX38, ZTX614QSTZ delivers 10× higher gain and 200 mV lower saturation voltage, enabling simpler drive circuitry; versus ZTX613, it provides polarity-specific functionality for low-side load control where NPN topology is mandated by system grounding.

Availability

ZTX614QSTZ is available at Aetrix Electronics and suitable for relay driver circuits, DC motor control stages, linear regulator pass elements, and industrial lamp dimming circuits requiring stable component supply and long-term manufacturability.

Supply support for ZTX614QSTZ 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, specializing in high-reliability components for industrial, automotive, and computing applications.

ZTX614QSTZ belongs to the ZTX series of high-gain medium-power transistors designed specifically for cost-sensitive, thermally constrained switching and amplification tasks in industrial control hardware.

FAQ

What is the maximum safe continuous collector current for ZTX614QSTZ at 75°C ambient?

At T_amb = 75°C, thermal derating reduces P_tot by (75 − 25) × 5.7 mW = 285 mW, leaving 715 mW available. Using V_CE(sat) = 1.25 V, maximum continuous I_C = 715 mW / 1.25 V ≈ 572 mA. This assumes adequate PCB copper area for heat spreading and no additional case temperature rise.

Can ZTX614QSTZ replace BCX38 in existing designs without layout changes?

Yes - ZTX614QSTZ uses the same E-line TO-92 package and identical E-B-C pinout as BCX38. However, its 5–10× higher h_FE may cause excessive base current draw if original base resistors were sized for BCX38's lower gain; recalculating R_B is recommended to avoid overdriving the base.

Is ZTX614QSTZ qualified for automotive applications per AEC-Q101?

No - ZTX614QSTZ is not AEC-Q101 qualified. While its T_j rating extends to +200°C, it lacks the stress testing, failure analysis, and traceability documentation required for automotive use. For AEC-Q101-compliant alternatives, consider Diodes' DXT614Q series.

What is the typical storage life of ZTX614QSTZ when kept in sealed moisture-barrier packaging?

When stored unopened in original moisture-barrier packaging at ≤30°C and ≤60% RH, ZTX614QSTZ maintains solderability and parametric integrity for ≥24 months. After opening, it must be baked per J-STD-033 prior to reflow if exposed to ambient for >168 hours.