Diodes Incorporated ZTX790ASTOA

Overview

ZTX790ASTOA from Diodes Incorporated is a PNP silicon planar medium-power high-gain bipolar junction transistor (BJT) designed for switching and linear amplification in low-voltage, moderate-current applications. It features V_CEO = −40 V, h_FE = 200 at I_C = −1 A, V_CE(sat) = −0.45 V (I_C = −1 A, I_B = −10 mA), and TO-92 compatible E-Line package. It is commonly used in siren drivers and battery-powered motor control circuits.

For engineers reviewing the ZTX790ASTOA datasheet, ZTX790ASTOA pinout, ZTX790ASTOA application, or ZTX790ASTOA equivalent, key selection considerations include its PNP polarity, −2 A continuous collector current rating, low saturation voltage under high drive, thermal resistance of 116 °C/W (PCB-mounted), and suitability for Darlington pair configurations in industrial alarm and portable power systems.

Technical Context

This PNP BJT operates with emitter-grounded configuration in common-emitter mode, supporting DC and pulsed switching up to 100 MHz (f_T). Its gain profile remains stable across I_C = −10 mA to −2 A (h_FE = 800 to 150), enabling consistent current amplification in both small-signal and medium-power stages.

The device exhibits low V_CE(sat) (−0.25 V to −0.75 V) across load currents up to −2 A, with base-emitter turn-on voltage of −0.75 V at I_C = −1 A. Thermal design relies on PCB copper area (≥1 in²) to achieve R_th(j–amb) = 116 °C/W, critical for sustained operation in ambient temperatures up to +100°C.

Key Specifications

Pinout & Package

Package: TO-92 compatible E-Line (3-lead, plastic, through-hole). Pin identification follows standard E-Line orientation: viewed from bottom (flat side facing user), leads left-to-right are Emitter (E), Base (B), Collector (C).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZTX790ASTOA, ZTX753STOA trades gain and saturation performance for enhanced voltage margin, while MJD2955G sacrifices package compactness and gain linearity for tenfold current capacity-making ZTX790ASTOA optimal for space- and efficiency-sensitive medium-power discrete switching.

Availability

ZTX790ASTOA is available at Aetrix Electronics and suitable for siren drivers, battery-powered motor control, Darlington pair amplifiers, and industrial alarm annunciators requiring stable component supply and long-term manufacturability.

Supply support for ZTX790ASTOA 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, computing, and consumer markets.

ZTX790ASTOA belongs to the ZTX series of general-purpose bipolar transistors, engineered for cost-effective, high-yield discrete switching and amplification in resource-constrained embedded systems.

FAQ

Is ZTX790ASTOA RoHS compliant and lead-free?

Yes, ZTX790ASTOA is RoHS compliant and lead-free per Diodes Incorporated's product change notice PCN-2019-01. The device uses matte tin-plated leads and halogen-free molding compound, meeting JEDEC J-STD-020 moisture sensitivity level 1 (MSL1) requirements for unlimited floor life at ≤30°C/85% RH.

Can ZTX790ASTOA replace BC557 in existing designs?

ZTX790ASTOA offers significantly higher I_C (−2 A vs. −100 mA) and h_FE (200 vs. 125 typical), but shares identical TO-92 pinout (E-B-C). Direct replacement is viable only if PCB layout accommodates higher power dissipation and thermal relief; base drive must be increased to ensure saturation at higher currents.

What is the maximum safe operating frequency for switching use?

ZTX790ASTOA achieves f_T = 100 MHz at I_C = −50 mA, but practical switching frequency is limited by stored charge and turn-off time. With I_B1 = −50 mA and I_B2 = −50 mA, t_off = 600 ns, supporting reliable operation up to ~300 kHz in PWM-driven loads with adequate base drive recovery.

Does ZTX790ASTOA require a heatsink in 1 A continuous operation?

No heatsink is required if mounted on a PCB with ≥1 in² copper area. At I_C = −1 A and V_CE(sat) ≈ −0.45 V, power dissipation is ~450 mW. With R_th(j–amb) = 116 °C/W, junction rise is ~52°C above ambient-well within the −55°C to +200°C rating at T_amb ≤ 70°C.