Diodes Incorporated BST15TA

Overview

BST15TA from Nexperia is a PNP silicon planar high-voltage transistor in SOT89 package, rated for VCEO = -200 V and IC = -500 mA, with VCE(sat) = -0.5 V at IC = -30 mA / IB = -3 mA, used in high-voltage switching and relay driver circuits.

For engineers reviewing the BST15TA datasheet, BST15TA pinout, BST15TA application, or BST15TA equivalent, key selection criteria include verified high-voltage blocking capability, low saturation voltage under pulsed drive, thermal performance in SOT89, and complementary pairing with BST40 for push-pull stages.

Technical Context

This PNP bipolar junction transistor operates in active and saturation regions with guaranteed breakdown voltages up to -200 V across both collector–base and collector–emitter terminals. Its hFE ranges from 30 to 150 at IC = -50 mA and VCE = -10 V, supporting stable current amplification in linear and switching modes.

The device exhibits fT = 15 MHz at IC = -10 mA and VCE = -10 V, enabling moderate-frequency switching up to ~10 MHz in practical designs. Cobo = 15 pF at VCB = -10 V confirms low output capacitance suitable for fast turn-off in high-voltage DC-DC and interface drivers.

Key Specifications

Pinout & Package

SOT89 package: 3-pin surface-mount plastic case with exposed emitter pad for thermal dissipation; pin 1 = Collector, pin 2 = Base, pin 3 = Emitter (C-B-E sequence as marked on top-side silkscreen).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC807-40 and MMBT4403LT1G, BST15TA delivers unique high-voltage robustness (-200 V) and SOT89 thermal capability (1 W), making it irreplaceable in mains-connected industrial controls without redesign.

Availability

BST15TA is available at Aetrix Electronics and suitable for industrial relay drivers, AC-DC interface protection circuits, and high-voltage DC-DC feedback loops requiring stable component supply across long-lifecycle programs.

Supply support for BST15TA 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

Nexperia is a global semiconductor expert focused on high-volume, high-reliability discrete and logic devices for automotive, industrial, and consumer applications.

BST15TA belongs to Nexperia's high-voltage bipolar transistor product line, engineered specifically for robust switching in mains-connected equipment and industrial control interfaces.

FAQ

What is the maximum continuous collector current for BST15TA?

The BST15TA is rated for -500 mA continuous collector current at Tamb = 25°C. Derating is required above 25°C ambient: approximately -5 mA/°C above 25°C, reaching zero at ~125°C case temperature. This rating assumes proper PCB copper area for thermal conduction from the exposed emitter pad.

Is BST15TA pin-compatible with BST15?

Yes - BST15TA shares identical SOT89 pinout (C-B-E), absolute maximum ratings, and electrical characteristics with BST15. The "TA" suffix denotes tape-and-reel packaging per JEDEC standard; no electrical or mechanical differences exist between BST15 and BST15TA.

Can BST15TA replace BST40 in a circuit?

No - BST15TA is a PNP transistor while BST40 is its complementary NPN counterpart. They serve opposite polarity roles: BST15TA sinks current from a positive rail, whereas BST40 sources current to ground. Swapping them would invert logic and likely cause malfunction or damage.

What is the recommended base resistor value when driving BST15TA from a 5 V microcontroller?

For saturation at IC = -30 mA, use IB = -3 mA (10× rule). With VBE(sat) ≈ -0.85 V and 5 V GPIO, R_B = (5 V − 0.85 V) / 3 mA ≈ 1.4 kΩ. A standard 1.5 kΩ resistor ensures reliable turn-on while limiting base current to safe levels under all operating conditions.