2SC1815 NPN-Transistor : Pinout, Equivalents and Datasheet

The 2SC1815 is a 50V 150mA general purpose NPN low-power silicon transistor with a maximum gain value of 700.  It is produced by Central Semiconductor. The tube withstand voltage is 40V, Pcm=400mW, Icm=150mA, and it adopts TO-92 package. The transistor polarity is NPN. This makes the transistor suitable for amplifier applications.

2SC1815 Pinout

2SC1815 Pin Description

Symbol

Footprint

3D Model

●General Purpose NPN Transistor

●DC Current Gain (hFE) 70 to 700

●Continuous Collector current (IC) is 150mA

●Collector-Emitter voltage (VCE) is 50V

●Collector-Base voltage (VCB) is 60V

●Emitter-base breakdown voltage (VEBO): 5V

●Collector-emitter saturation voltage drop (VCE): 0.25V

●Transition Frequency: 80MHz

●Base current (IB): 50mA

●Power dissipation (PC): 400mW

●Available in To-92 Package

Central Semiconductor 2SC1815 technical specifications, attributes, parameters and parts with similar specifications to Central Semiconductor 2SC1815.

The 2SC1815 is a general-purpose NPN transistor that is commonly used in Amplifier applications. There are four variants, the 2SC1815O will have a gain value of 70 to 140 and the 2SC1815Y will have 1020 to 240, the 2SC1815GR will have 200 to 400 and the 2SC1815L will have a gain range from 350 to 700.

This NPN transistor also has its counterpart PNP transistor the 2SC1015, which makes it ideal for Push-pull and class B amplifier designs. Apart from this, the transistor can also be used for switching low power devices.

Differential Amplifier Schematic

1. The sum of Tr1 and Tr2 emitter current is a fixed value

As shown in the figure, assuming that Tr1 and Tr2 are exactly the same when there is no input signal, the respective emitter currents Ie1 and Ie2 are the same, and both are half of the emitter current of the constant current source Tr3. When a voltage is applied to input 1, Ie1 increases by ΔIe. Because Ie1+Ie2 is controlled by the constant current source Tr3, Ie2 decreases by ΔIe, that is, Ie1 and Ie2 have the same amount of change, but the direction of increase and decrease is different.

2. Amplify the difference of the input signal

The output of this circuit is taken out by the change in collector current (=emitter current) and the voltage drop on the collector resistance.

ΔIe is determined by the difference between the Vbe of Tr1 and Tr2. When the two input signals are the same, the Vbe of Tr1 and Tr2 is the same, and the difference between the two is zero, so there is no output.

When the two input signals are different, the changes of Ie1 and Ie2 are equal in magnitude and opposite in direction, so Vo1 and Vo2 are signaling with the same amplitude and opposite phase.

Therefore, the differential amplifier circuit only amplifies the difference between the two input signals and does not amplify the same input signal, so it can play a role in suppressing temperature drift.

3. The gain of the differential amplifier

The input of the differential amplifier has two forms of single-ended input and double-ended input, and the output also has two forms of single-ended output and double-ended output.

The gain of the double-ended output is: AV=RC/RE

The gain of single-ended output is: AV=RC/2RE

That is, the single-ended output gain is half of the double-ended output.

It can be seen that the gain of the differential amplifier is the same as that of the single-tube common emission amplifier. The addition of a tube does not increase the gain, but the temperature drift is well restrained.

Simulation Circuit

The differential input voltage Vid≤100mV, the amplifier circuit gain≥20dB, that is 10 times, because the actual gain is always smaller than the theoretical calculation value, so the theoretical calculation gain is positioned at 20 times, and the maximum output voltage is 100mV×20=2V.

The power supply voltage of the differential amplifier is larger than the maximum output voltage plus the voltage drop on the emitter resistor Re3 of Tr3 working as a constant current source.

If the voltage drop of Re3 is 2V, the power supply voltage should be above 4V. In order to make the base voltage of Tr1 and Tr2 0V, remove the coupling capacitance on the input side and simplify the circuit, so a ±5V dual power supply is used.

The collector current of Tr1 and Tr2 is generally 0.1 to several milliamperes. Here is set to 1mA, then the emitter current of the constant current source Tr3 is set to 2mA. Let the voltage drop on Re3 be 2V and the current flows through 2mA, so

Re3=2V/2mA=1kΩ

In order to make the voltage drop on Re3 2V, set Vbe to 0.6V, then the voltage drop on R2 is 2.6V, so the voltage drop on R1 is 7.4V.

In order to make the base current on Tr3 negligible, the current flowing on R1 and R2 must be more than 10 times larger than the base current. If β=100, the base current of Tr3 is

Ib3=2mA/100=0.02mA

So the current flowing through R1 and R2 is 0.2mA.　R1=7.4V/0.2mA=36kΩ　R2=2.6V/0.2mA=13kOΩ

▲Use in general-purpose switching

▲Use in class B amplifiers

▲Use in pre-amplifier circuits

▲Use in push-Pull configuration circuits

Central Semiconductor is a leading provider of superior discrete semiconductors that have been applied in electronic products all over the world since 1974. Nowadays, the company's products lines contain MOSFETs, bridge rectifiers, silicon carbide devices, protection devices, rectifiers, current limiting diodes, bipolar power transistors, standard, and custom small-signal transistors, and thyristors. 

Except for the industry-standard surface mount, the company's products also support bare die, MDMs (Multi Discrete Modules™), through-hole packages. With the loyal and high-quality brand image it has built, Central keeps leveraging its service capability and benefit more and more customers through exclusive high-tech products.

Download datasheets and manufacturer documentation for Central Semiconductor 2SC1815.