Diodes Incorporated ZTX757

Overview

ZTX757 from Zetex Semiconductors (now Diodes Incorporated) is a PNP silicon planar medium-power high-voltage transistor with V_CEO = −300 V, I_C = −0.5 A continuous, P_tot = 1 W at T_amb = 25°C, and h_FE ≥ 40 at I_C = −100 mA, used in high-voltage switching and linear regulation circuits for industrial power supplies.

For engineers reviewing the ZTX757 datasheet, ZTX757 pinout, ZTX757 application, or ZTX757 equivalent, key selection criteria include verified −300 V V_CEO, −0.5 A I_C rating, TO-92 package compatibility, h_FE stability across I_C = −10 mA to −100 mA, and safe operating area compliance up to 200°C junction temperature.

Technical Context

This PNP bipolar junction transistor employs a planar epitaxial structure optimized for high-voltage blocking and medium-current switching. Its −300 V V_CEO and −200 V V_CBO ratings enable use in flyback snubbers and relay drivers where voltage transients exceed 250 V.

With f_T = 30 MHz and switching times (t_d/t_r/t_f/t_s) specified under I_C/I_B = 10 conditions, it supports moderate-speed switching (≤100 kHz) while maintaining low V_CE(sat) = −0.5 V at I_C = −100 mA and I_B = −10 mA.

Key Specifications

Pinout & Package

Supplied in E-Line TO-92 compatible package (3-lead plastic case), with standard emitter-base-collector (E-B-C) terminal arrangement matching JEDEC TO-92 outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD2955G and ZTX753, ZTX757 uniquely balances −300 V capability, TO-92 form factor, and 1 W dissipation-making it optimal for space-constrained, high-voltage industrial controls where neither lower-voltage nor higher-power alternatives meet all three requirements simultaneously.

Availability

ZTX757 is available at Aetrix Electronics and suitable for industrial relay drivers, high-voltage linear regulators, flyback snubbers, and high-side load switches requiring stable component supply across extended production cycles.

Supply support for ZTX757 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, acquired by Diodes Incorporated in 2008, specialized in high-performance discrete semiconductors for industrial, automotive, and power management applications.

ZTX757 belongs to the ZTX series of high-voltage PNP transistors designed specifically for robust switching and linear operation in harsh-voltage environments such as AC/DC front-ends and isolated power stages.

FAQ

What is the maximum allowable junction temperature for ZTX757?

The ZTX757 has an absolute maximum junction temperature (T_j) of +200°C, validated per its safe operating area curves and thermal resistance data. Operation above this limit risks permanent degradation of the planar epitaxial structure and h_FE collapse. Derating begins at T_amb > 25°C per the published θ_JA = 50°C/W curve.

Can ZTX757 be used in avalanche mode?

No, ZTX757 is not rated or characterized for controlled avalanche operation. Its V_(BR)CEO = −300 V is a breakdown limit-not an avalanche energy rating-and repeated operation near this voltage without current limiting may cause irreversible second breakdown or parametric shift.

Is ZTX757 RoHS compliant and lead-free?

Yes, ZTX757 is RoHS compliant and lead-free, meeting Directive 2011/65/EU Annex II substance restrictions. Diodes Incorporated's product change notification (PCN) #14-003 confirms halogen-free molding compound and lead-free termination finish for all ZTX75x devices manufactured after Q3 2014.

Does ZTX757 require a base resistor in switching applications?

Yes, a base resistor is mandatory to limit I_B and ensure saturation. For I_C = −100 mA and h_FE = 40, minimum I_B = −2.5 mA is required. With V_BE(sat) = −1.0 V and a −5 V drive, R_B ≈ 1.6 kΩ provides appropriate margin while avoiding excessive base current.