STMicroelectronics STX690A

Overview

STX690A from STMicroelectronics is a high-performance, low-voltage NPN bipolar junction transistor optimized for switching and power management. It delivers V_CE(sat) as low as 0.08 V at I_C = 0.5 A / I_B = 5 mA, h_FE ≥ 100 at I_C = 10 mA, 3 A continuous collector current, and 40 V V_(BR)CER breakdown rating-used in battery charger switching regulators and portable equipment bias supplies.

For engineers reviewing the STX690A datasheet, STX690A pinout, STX690A application, or STX690A equivalent, key selection criteria include saturation voltage under heavy load, DC gain stability across I_C = 10 mA–3 A, thermal resistance (139 °C/W), TO-92 mechanical compatibility, and R_BE-assisted breakdown margin (V_(BR)CER = 40 V).

Technical Context

This NPN transistor employs ST's "Base Island" planar layout to simultaneously maximize h_FE and minimize V_CE(sat). Its V_(BR)CER = 40 V (with 47 Ω base-emitter resistor) enables robust operation in regulated bias rails where transient overvoltage may occur without external clamping.

Switching performance is characterized with resistive load: t_d = 50 ns, t_r = 120 ns, t_s = 465 ns, t_f = 80 ns at I_C = 3 A, confirming suitability for medium-frequency (<100 kHz) hard-switching applications such as linear-mode battery charge control and load switching.

Key Specifications

Pinout & Package

STX690A is housed in a standard TO-92 plastic package (JEDEC TO-226AA), with lead finish compliant with RoHS and ECOPACK® environmental standards. Dimensions conform to ST's mechanical drawings for bulk and ammopack variants.

Key Features

Applications

Availability

STX690A is available at Aetrix Electronics and suitable for battery charger switching regulators, portable equipment power management, and voltage regulation in bias supply circuits requiring stable component supply and legacy-compatible TO-92 sourcing.

Supply support for STX690A 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The STX690A belongs to ST's legacy low-voltage power transistor family, engineered specifically for high-efficiency, low-saturation switching in space-constrained portable and battery-operated systems.

FAQ

What is the maximum safe collector-emitter voltage for STX690A in standard switching use?

The absolute maximum V_CEO is 30 V with open-base condition. However, with a 47 Ω resistor between base and emitter (R_BE), V_(BR)CER rises to 40 V-this configuration is recommended for improved ruggedness in regulator and charger applications where transient overvoltage may occur.

Can STX690A replace BC337-40 in existing designs?

Yes, STX690A is pin-compatible with BC337-40 in TO-92 and offers superior specs: lower V_CE(sat) (0.08 V vs. typical 0.2 V), higher h_FE consistency at high current, and enhanced V_(BR)CER. No circuit changes are needed, but thermal performance should be verified due to higher P_tot (0.9 W vs. 0.625 W).

Is STX690A suitable for linear amplifier applications?

No-it is optimized for switching and saturated operation, not linear amplification. Its h_FE variation across V_CE and limited f_T linearity make it unsuitable for audio or precision analog gain stages. Use dedicated small-signal transistors like BC547 or PN2222 for such roles.

Does STX690A have lead-free and RoHS-compliant packaging?

Yes, STX690A is manufactured in ECOPACK®-compliant TO-92 packages meeting RoHS Directive 2011/65/EU. Both bulk (STX690A) and ammopack (STX690A-AP) variants use lead-free terminations and halogen-free molding compounds per ST's environmental specifications.