BC857 SMD transistor
BC857 transistor electrical specification
- BC857 is a PNP general-purpose SMD transistor device
- Collector to emitter voltage is -45V
- Collector to base voltage is –50V
- Emitter to base voltage is –5V
- Collector current is -0.1A
- Power dissipation is 250mW
- DC current gain is 125 to 800hFE
- Current gain-transition frequency (FT) is 100MHz
- Junction temperature is between -65 to 150℃
- Collector to emitter saturation voltage (VCE (SAT)) is -0.65 to -0.3V
- Noise figure (NF) is 2 to 10dB
- Output capacitance (Cob) is 5pF
- Low current
- Low voltage
- Low power surface mount transistor
BC857 transistor Pinout
| Pin Number | Pin Name | Description |
| 1 | Base | Base is used to trigger the transistor device |
| 2 | Emitter | Current flows through the emitter |
| 3 | Collector | Current flow through the collector |
BC857 transistor package
The BC857 SMD transistor had a SOT-23/SC-70 surface-mount package, it is a common SMD package used at circuits.
The SOT-23 package is made with epoxy material for higher heat resistance and it is very compact and has less weight.
BC857 transistor electrical specification description/ application
In this section, we try to explain the electrical specifications of the BC857 SMD transistor.
Voltage specs
The terminal voltage specs of the BC857 transistor are collector to base voltage is -50V, collector to emitter voltage is -45V, and emitter to base voltage is -5V.
The collector to emitter saturation voltage is -0.65V to -0.3V, it is a voltage value less than the base voltage and switching voltage of the transistor device.
Overall the voltage specification of BC857 SMD transistor shows that it is a medium power PNP transistor device that has more applications for general-purpose devices.
Current specs
The collector current value of the transistor is -0.1A, it is a device having less current driver applications.
Dissipation specs
The power dissipation of the BC857 transistor is 250mW, and the dissipation value of this surface mount device is less than the equivalent through-hole model
Current gain specs
The current gain value of the BC857 transistor is 125 to 800hFE, and the DC current value is been mainly useful for amplification applications.
Transition frequency
The bandwidth transition frequency value of the BC857 transistor is 100MHz, it is the frequency range of the transistor used in audio applications.
Junction temperature
With the junction temperature and operating temperature of this device being -65 to 150℃, the heat capacity of the transistor is mainly dependent on the case and operating temperature limit of the component.
Noise figure
The noise figure value of the transistor is 2 to 10dB
Output capacitance
The output capacitance value of the BC857 transistor is 4.5pF
BC857 SMD transistor DATASHEET
If you need the datasheet in pdf please click this link
BC857 transistor equivalent
The transistor devices such as BC856, FMMTA56, KST55, PMBTA92, 2SA1519, BC860, MMBTA56, SMBTA56, and KST92 are the equivalent transistor devices of BC857. The electrical specifications of these transistor devices are the same.
BC857 SMD transistor complementary pair
The complementary pair for BC857 PNP transistors are BC847 and BC846 NPN transistors.
BC857 vs 2SA1518 vs BC860
In this table, we try to compare the electrical specifications of three SMD transistor devices such as BC857, 2SA1518, and BC860.
This comparison table will help us to know more about these devices for the replacement process.
| Characteristics | BC857 | 2SA1518 | BC860 |
|---|---|---|---|
| Collector to base voltage (VCB) | -50V | -50V | -45V |
| Collector to emitter voltage (VCE) | -45V | -50V | -50V |
| Emitter to base voltage (VEB) | -5V | -10V | -5V |
| Collector to emitter saturation voltage (VCE (SAT)) | -0.65V to -0.3V | -0.25V | -5V |
| Collector current (IC) | -0.1A | -0.5A | -0.1A |
| Power dissipation | 250mW | 0.2W | 0.25W |
| Junction temperature (TJ) | -65 to +150°C | -55 to +150°C | -65 to +150°C |
| Transition frequency (FT) | 100MHZ | 200MHZ | 150MHz |
| Gain (hFE) | 125 to 800hFE | 50hFE | 110 to 800hFE |
| Output capacitance | 4.5pF | - | - |
| Noise figure | 2 to 10dB | - | 1dB |
| Package | SOT-23/ SC-70 | SOT-23/ TO-92 | SOT-23 |
Most of the electrical specs of these three transistor devices such as BC857, 2SA1518, and BC860 are the same, but each of them had its specialties.
The voltage specs, current specs, and power dissipation wise BC857 and BC860 transistors had the same values, so we can replace each of them and use them for almost the same applications.
The 2SA1518 transistor had a different electrical specs value compared to the other two transistors.
BC857 SMD transistor applications
- General-purpose switching applications
- Amplifier circuit applications
- Automotive applications
Characteristics curves of BC857 SMD transistor
The figure shows the DC current gain characteristics of BC857 SMD transistor, the graph is plotted with dc gain vs collector current.
At a fixed collector to the emitter voltage value and different junction temperature values, the gain values of the transistor will start at a higher will temperature is high.
The figure shows the collector to emitter saturation voltage characteristics of the BC857 transistor, the graph is plotted with the collector to emitter saturation voltage vs collector current.
