BC847 is a common surface mount SMD transistor. Transistor is commonly labelled as 1E, 1F and 1G. In this article I’m sharing the information’s about this transistor pinout, specifications and equivalent transistors for replacement. i would like to share some additional information like comparisons and differences also.
What is the BC847 Transistor?
BC847 is a SOT-23 SMD type of surface mount NPN transistor. This can be using for general purposes like signal amplification, switching purpose and relay control circuit. This transistor is mainly designed for the low power, low noise and low signal distortion. This transistor collector emitter voltage is about 45V and current capacity about 100mA.
How to Read the BC847 Marking Code (Not Just ‘BC847’)
The BC847 transistor is visible in the circuit board in marking codes not like the old numbering method. The two character are used to numbering the SOT-23 transistor. the transistor with 3 number means the third one represents the manufacturer. The common marking code is given below,
| Part Number | Marking Code | Gain Group (hFE) | Gain Level |
|---|---|---|---|
| BC847A | 1E | 110 – 220 | Low |
| BC847B | 1F | 200 – 450 | Medium |
| BC847C | 1G | 420 – 800 | High |
| BC847 (Generic) | 1H | Not specified | General use |
BC847 Pinout
In SOT-23 transistor package, the transistor has three pins arranged with two pins on one side and one pin on the other side. When we viewed from the top hold the flat surface facing you and the the single pin at the top is usually the collector.
while the two pins at the bottom are the base and emitter pins. Specifically, the bottom-left pin is the base, and the bottom-right pin is the emitter in common NPN transistors like the BC847 series. This compact arrangement is designed for surface-mount circuits and it is easy to identify the connections once you know the orientation.
Specifications
- Type is NPN
- SOT-23 package
- Maximum Voltage is 45V
- Maximum Current is 100mA
- Gain is Generally 110 to 800, which varies with the suffix.
- Operating Temperature is around -65 to +150 degree celcius.
Transistor Pinout Configuration
| Pin Number | Position | Function |
|---|---|---|
| 1 | Bottom Left | Base (B) |
| 2 | Bottom Right | Emitter (E) |
| 3 | Top (Single Pin) | Collector (C) |
Equivalent Transistor for Replacement
If you can not find the transistor you can use the direct SMD alternative of BC847A, BC847B, BC847C. You can also use other SMD transistors of BCW71R, BCW72R, MMBT3904, BC846. There are some through hole type transistors can be used if no way to get the SMD which are, BC547, BC548, 2N2222, 2N3904.
✔Note: Make sure that the features like voltage and current are same or your requirement. always check the specifications and pinout configuration before replacing the transistior.
Working of BC847 Transistor
This transistor is a NPN type of transistor, it can control the large current by using a small voltage applying on the base pin of the transistor. When a small current is passed though the base emitter pins, that time large current allow to pass through the collector to emitter pins.
In practical circuit, this Turn ON and OFF referee the switching action of the transistor. The base pin has no positive voltage that time the transistor is in OFF state. This called its cut OFF region. The transistor only pass the current through collector to emitter if the sufficient positive voltage received in the base pin of the transistor.
BC847 vs BC547 what is the difference
The BC847 and BC547 transistors are similar to its electrical characteristics but some differences rea present, which are listed below,
| Feature | BC847 | BC547 |
|---|---|---|
| Transistor Type | NPN | NPN |
| Package Type | SMD (SOT-23) | Through-hole (TO-92) |
| Mounting Style | Surface Mount | Through Hole |
| Size | Very small | Larger |
| Pin Configuration | 2 pins bottom, 1 pin top | 3 pins in a row |
| Typical Use | Compact circuits, PCB SMD designs | Breadboards, general-purpose circuits |
| Collector Current | ~100 mA | ~100 mA |
| Collector-Emitter Voltage | ~45 V | ~45 V |
| Gain Groups | A, B, C (like BC847A/B/C) | A, B, C (like BC547A/B/C) |
| Marking Code | Short SMD codes (e.g., 1E, 1F, 1G) | Full part number printed |
Advantage of using BC847
- Compact in size so very less space is needed to place and total board size reduced.
- Complementary pair is available to build push pull circuits.
- It has low noise and high voltage handling capacity, so perfect for audio amplification and pre signal amplification.
BC847 vs BC817: When to Upgrade for Higher Current
The BC847 transistor has the maximum collector current of 100mA. If the circuit want more current then i prefer to use BC817 as the alternative way of placing in the same space. The BC817 provides high gain than the 847 transistor so it can be a considerable for the replacement. you can check the quick comparison table i given below,
| Feature | BC847 | BC817 |
|---|---|---|
| Max Collector Current (Ic) | 100 mA | 500 mA – 800 mA |
| Collector-Emitter Voltage (Vce) | 45 V | 45 V |
| Primary Usage | Low-power / Small-signal | Medium-power / Driving loads |
| Package | SOT-23 | SOT-23 |
| Transition Frequency (fT) | ~100–150 MHz | ~100 MHz |
Common Applications
- Signal amplification
- Switching circuit
- Small signal regulation circuits.
