BC557 transistor

BC557 transistor
BC557 transistor

BC557 transistor specifications

  • It is a Bipolar PNP Transistor
  • DC Current Gain range is 125 to 800hFE
  • Collector current (IC) is -100mA
  • Collector to base Voltage (VCB) is -50V
  • Collector to emitter voltage (VCE) is -45v
  • Emitter to base voltage (VEB) is -5V
  • Junction temperature (TJ) is 150°C
  • Power dissipation at the transistor is 500mW
  • Transition frequency (FT) is 100MHz

 BC557 pinout

Pin Number Pin Name Description
1 Collector Current flows through the collector terminal
2 Base The base terminal triggers the transistor
3 Emitter Current flows through the emitter
 BC557 pinout
BC557 pinout

TO-92 package

The package used to build the BC557 transistor is the TO-92, the package is made with a mixture of plastic and epoxy.

The BC557 transistor is a general-purpose transistor type, which had more applications at the common electronic appliance, due to this the cost for a transistor is the problem. One of the advantages of TO-92 is it is less expensive and compatible with circuits.

BC557 Description

A BC557 transistor had general-purpose applications, this is the reason why the BC557 transistor has low voltage and low current specifications.

The current gain on the BC557 transistor is starting at 125 to 800Hfe, the gain value is very important at applications like an amplifier and the BC557 transistor had high gain values.

The collector current at the BC557 transistor is -100Ma, the negative value is the indication of it is a PNP transistor, the maximum load current at BC557 is lower this is because BC557 is a general-purpose transistor.

The power dissipation at the bc557 transistor device is 625mW, this dissipation value indicates the maximum power dissipation on a device, and the BC557 transistor only had low power applications.

The transition frequency value on the BC557 transistor is 100MHZ, it is important at switching applications

The junction temperature of the BC557 transistor is 150°C.

Bc557 transistor datasheet 

Bc557 transistor datasheet
Bc557 transistor datasheet

If you need the datasheet in pdf please click this link

BC557 transistor Equivalent 

The transistor equivalent for BC557 is BC157, BC558, TIP127, BC327, and BC560.

The equivalent transistors at this list are equivalent, so we can replace the BC557 with these transistors.

The electrical specifications of the BC557 transistor and these transistors are almost the same, but at the practical circuits we need accurate value, so on the replacement, we need to cross-check the voltage and current specifications.

BC557 vs BC547 vs 2n3906 vs BC327

The table below is used to compare each transistor’s special specifications, at the table we include transistors similar to BC557 and the complementary pairs.

The list of transistors is BC557 vs BC547 and 2n3906 vs BC327, the table comparison of transistors is really useful for the replacement process.

Characteristics BC557 Bc547 (NPN) 2N3906 BC327
Collector to base voltage (VCB)-50V50V-40V-50V
Collector to emitter voltage (VCE) -45V45V-40V-45V
Emitter to base voltage (VEB)-5V6V-5V-5V
Collector current (IC)-100mA100mA-200mA-800mA
Power dissipation 500mW500mW625mW625mW
Junction temperature (TJ)150°C150°C150°C150°C
Transition frequency (FT)100MHZ300MHZ250MHZ260MHZ
Noise (N)10dB10dB4dB-
Gain (hFE)125to 800hFE110 to 800hFE30 to 300hFE40 to 630Hfe
Package TO-92TO-92TO-92TO-92

 BC557 transistor uses

  • Used to drive loads up to 100Ma.
  • Preamp amplifiers
  • Relay driver circuits
  • Small signal amplifiers
  • Motor driver circuits

Bc557 transistor as a switch

Bc557 transistor as a switch
Bc557 transistor as a switch

The figure shows a model circuit of BC557 transistor as a switch, the very nature of a transistor is the switching operation.

The figure shows the idea behind the working of the BC557 transistor as a switch, when the voltage passes to the transistor, it triggers ON and passes a tiny signal to the LED.

The ON and OFF time will be control with the resistors combined with the transistor and make it an operating switch.

BC557 relay circuit

BC557 relay circuit
BC557 relay circuit

The figure shows the circuit of relay driver using BC557 transistor, we know the operation of the relay at circuits.

In most of the applications, the relay is dealing with higher voltage and current specifications, and at the operation, the relay coil sometimes generates electrical sparks.

The operation of transistors at the relay driver circuits is to prevent the high voltage strike at the circuits, the BC557 transistor makes an alternative for the high current generate on the relay switching.

BC557 transistor price

The BC557 is a general-purpose transistor device, which had more applications at common applications.

The price for a BC557 transistor had a price of 10rupees for 5 pieces or 0.13USD dollars.

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