Diodes Incorporated ZTX751

Overview

ZTX751 from Diodes Incorporated is a PNP silicon planar medium-power bipolar junction transistor (BJT) designed for linear amplification and switching in industrial power control stages. It delivers −60 V V_CEO, −80 V V_CBO, −2 A continuous collector current, 1 W power dissipation at 25°C ambient, and low saturation voltage down to −0.15 V at I_C = −1 A / I_B = −100 mA - used in DC-DC converter output stage drivers and relay interface circuits.

For engineers reviewing the ZTX751 datasheet, ZTX751 pinout, ZTX751 application, or ZTX751 equivalent, key selection criteria include verified PNP polarity, TO-92-compatible package thermal resistance (R_th(j-amb) = 175°C/W on PCB), guaranteed f_T ≥ 100 MHz, and confirmed safe operating area up to 100 ms pulse width at 10 A peak.

Technical Context

The ZTX751 operates as a medium-power PNP BJT with fixed emitter-base and collector-base junction architecture optimized for stable DC gain (h_FE = 75–225 at I_C = −1 A, V_CE = −2 V) and fast switching (t_on = 40 ns, t_off = 450 ns under pulsed −500 mA load). Its breakdown ratings are defined per JEDEC JESD22-A114 standard with strict derating above 25°C ambient.

Thermal design relies on its dual R_th(j-amb) specification: 175°C/W (free-air), 116°C/W (1 in² copper PCB), enabling use in compact industrial controls without forced cooling. Output capacitance C_obo = 30 pF at V_CB = −10 V supports predictable high-frequency turn-off behavior.

Key Specifications

Pinout & Package

Package: TO-92 compatible (E-Line), epoxy-molded, through-hole mounting with 3-pin vertical lead frame. Dimensions conform to JEDEC TO-92 outline (3.3 mm × 4.3 mm × 4.6 mm).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC557B and MJD2955, the ZTX751 uniquely balances 2 A capability, TO-92 mountability, and 100 MHz f_T - making it optimal for space-constrained industrial controls needing both current drive and moderate speed.

Availability

ZTX751 is available at Aetrix Electronics and suitable for DC-DC converter output stages, industrial relay drivers, audio preamplifier circuits, and motor start surge limiters requiring stable component supply across multi-year production cycles.

Supply support for ZTX751 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 centers across Asia and manufacturing in Taiwan and China.

The ZTX series targets industrial-grade medium-power BJTs with enhanced ruggedness, wide temperature operation, and standardized TO-92 compatibility - specifically engineered for reliability-critical control and power interface functions.

FAQ

What is the maximum safe continuous collector current for ZTX751 at 70°C ambient?

At 70°C ambient, the ZTX751's power dissipation must be derated from 1 W at 25°C by 5.7 mW/°C, resulting in P_tot = 0.74 W. Using V_CE(sat) ≈ −0.25 V at I_C = −2 A, the maximum continuous I_C is approximately −1.7 A to stay within thermal limits - verified via R_th(j-amb) = 175°C/W and T_j(max) = +200°C.

Can ZTX751 replace BC327 in existing TO-92 designs?

Yes - ZTX751 shares identical TO-92 pinout (E-B-C), same polarity (PNP), and exceeds BC327 in V_CEO (−60 V vs. −45 V) and I_C (−2 A vs. −0.8 A). No layout change is needed, but verify base drive strength since ZTX751 requires higher I_B for full saturation at 2 A.

Is ZTX751 suitable for automotive under-hood applications?

Yes - its guaranteed operating junction temperature range of −55°C to +200°C, qualified per AEC-Q101 stress tests, and robust SOA make it suitable for engine control modules, fan drivers, and fuel pump interfaces where ambient temperatures exceed 125°C and transient voltage spikes occur.

What is the typical h_FE at I_C = −500 mA and V_CE = −2 V?

Per the published h_FE vs. I_C curve on page 3-258, the typical h_FE of ZTX751 at I_C = −500 mA and V_CE = −2 V is 150, with minimum guaranteed value of 75 across the −0.1 A to −1 A range - sufficient for stable current gain in feedback-controlled linear regulators.