Diodes Incorporated BCX19TA

Overview

BCX19TA from Diodes Incorporated is an NPN silicon planar medium-power transistor in SOT23 package, rated for V_CEO = 45 V, I_C = 500 mA, P_TOT = 330 mW at T_amb = 25°C, with h_FE = 100–600 (IC = 100 mA), and f_T = 200 MHz - used in low-voltage switching and linear amplification stages of portable power management circuits.

For engineers reviewing the BCX19TA datasheet, BCX19TA pinout, BCX19TA application, or BCX19TA equivalent, key selection criteria include DC current gain consistency across 100–500 mA, V_CE(sat) ≤ 620 mV at I_B = 50 mA, thermal stability up to +150°C junction temperature, and SOT23 footprint compatibility with space-constrained PCB layouts.

Technical Context

This NPN transistor operates in active, saturation, and cutoff regions with verified DC current gain (h_FE) spanning 100–600 depending on collector current (100 mA to 500 mA) and V_CE = 1 V. Its transition frequency of 200 MHz at I_C = 10 mA / V_CE = 5 V supports RF-coupled pre-amplifier and oscillator buffer roles up to ~35 MHz.

Thermal design is constrained by 330 mW total power dissipation at ambient 25°C and a maximum junction temperature of +150°C. The device exhibits low output capacitance (C_obo = 5.0 pF at V_CB = 10 V, f = 1 MHz), enabling fast switching transitions in pulse-width modulated load control.

Key Specifications

Pinout & Package

SOT23 plastic surface-mount package with gull-wing leads; 3-terminal configuration optimized for automated placement and reflow soldering on dense PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BCX19TA, BC817-40 offers higher minimum h_FE for improved low-current linearity, while MMBT2222ALT1G trades 5 V V_CEO headroom for broader h_FE consistency - both retain SOT23 compatibility but differ in thermal derating curves and pulse current capability.

Availability

BCX19TA is available at Aetrix Electronics and suitable for LED driver stages, low-voltage switch-mode circuits, audio pre-amplifiers, and industrial sensor interfaces requiring stable component supply and SOT23 footprint continuity.

Supply support for BCX19TA 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 power management, signal integrity, and protection.

The BCX19TA belongs to Diodes' general-purpose bipolar transistor product line, designed for cost-effective, thermally robust switching and amplification in space-constrained industrial and portable applications.

FAQ

What is the maximum continuous collector current for BCX19TA?

The BCX19TA is rated for 500 mA continuous collector current (I_C) at ambient temperature 25°C. Derating is required above 25°C per the thermal resistance curve in the official datasheet; at 70°C ambient, maximum I_C drops to approximately 350 mA to maintain junction temperature ≤150°C.

Is BCX19TA suitable for switching inductive loads like relays?

Yes, BCX19TA can switch inductive loads such as relays, provided external flyback protection (e.g., a reverse-biased diode across the coil) is used. Its V_CEO = 45 V and I_CM = 1000 mA peak allow safe operation with typical 5–12 V relay coils drawing ≤500 mA, assuming proper base drive and thermal layout.

How does BCX19TA's h_FE vary with collector current?

h_FE is specified as min 100 at I_C = 100 mA, min 70 at I_C = 300 mA, and min 40 at I_C = 500 mA (all at V_CE = 1 V). This intentional roll-off reflects silicon process characteristics and ensures stable operation across its full rated current range without thermal runaway.

Can BCX19TA replace BCX17 in complementary pair circuits?

No - BCX17 is the PNP complement to BCX19, with mirrored parameters (e.g., V_ECO = 45 V, I_C = −500 mA). While BCX19TA and BCX17 share package and voltage/current ratings, their polarity prevents direct substitution; using BCX19TA in place of BCX17 would invert circuit function and likely cause failure.