A684 Transistor Pinout, Equivalent, Uses, Features, Explanation and Other Info

This post contains all the details about 2SA684 or A684 transistor pinout, equivalent, uses, features, explanation and other info.


A684 Transistor Pinout, Equivalent, Uses, Features, Explanation and Other Info



Features / Technical Specifications

  • Package Type: TO-92L
  • Transistor Type:  NPN
  • Max Collector Current(IC): -1A
  • Max Peak Collector Current(ICP): -5A
  • Max Collector-Emitter Voltage (VCE): -50V
  • Max Collector-Base Voltage (VCB): -60V
  • Max Emitter-Base Voltage (VEBO): -5V
  • Max Collector Dissipation (PC): 1 Watt
  • Max Transition Frequency (fT): 200 MHz
  • Minimum & Maximum DC Current Gain (hFE): 85 – 340
  • Max Storage & Operating temperature Should Be: -55 to +150 Centigrade


NPN Complementary:

NPN Complementary of 2SA684 is 2SC1384


Replacement and Equivalent

2SA0683 2SA0684, 2SA683


2SA684 Transistor Explained / Description

2SA684 or A684 is a silicon planar epitaxial transistor designed to be used in applications such as driver and power amplification for low frequency, but it can also be used in other applications which we will discuss later in this article. The transistor is available in TO-92L package. The TO-92L package is slightly taller than the common TO-92 package.

Looking at the absolute max ratings of the transistor the collector-emitter voltage of the transistor is -50V, collector-base voltage is -60V, emitter-base voltage is -5V, collector power dissipation is 1W, minimum to maximum DC current gain is 85 to 340, max collector current is -1A and peak collector current is 1.5A.

Electrical Characteristics of the transistor are collector-emitter saturation voltage is -0.2V to -0.4V, transition frequency is 200MHz, collector output capacitance is 20 typical and 30pF max.

The transistor is manufactured in three different gain values and can be determined by the alphabet written after the part number. So if that alphabet is “Q” then its hFE  will be 85 to 170, if the alphabet is “R” then its hFE will be 120 to 240 and if “S” then its hFE will be 170 to 340.


Where & How to Use

2SA684 transistor is designed for low frequency power and driver amplification but due to its versatile features and specs, this transistor can be used in variety of other applications too such as switching circuits, drive applications, power supplies, solar etc.



Driver Amplification

Audio Amplifiers

Power Supplies

LED Driver Circuits

Radio and RF Circuits

Switching Applications


Variety of General Purpose Applications


Safe Operating Guidelines

All electronic components have some limits so the transistors too have limits and using them under their limits is important for their long term and stable performance, therefore for getting long term performance use them atleast 20% below from their limits. According to the data of 2SA684 transistor it’s max collector current is -1A therefore do not drive load of more than 800mA, the max collector to emitter voltage is -50V therefore do not drive load of more than 30V and always store or operate at temperature above -55 °C.



To Download the datasheet just copy and paste the below link in your browser.


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