#2n2222 transistor max current full

You can find a good technical app note on PWM DAC design from TI here. You will either have to sacrifice the range you can control, or the max current you can use, or change the PWM voltage, or change the LED source voltage.

#2n2222 transistor max current full

So you may not find an optimal solution that gets you full scale dimming. (5-3)/R2 = Max Current (not accounting for Vce of the transistor to make it simple). If you are using a white LED with a 3V drop at the current you need: To utilize the full PWM voltage range 0-3.3V or 0-5V, to give you the largest range of current control, you want the voltage across R2 to be the max PWM voltage 100% duty cycle at the max current you want.īut you need to make sure that the resistor that gives you that value actually allows that current. So this particular circuit will need to be adjusted to your needs. Really what the forward voltage is at the currents you want. Now we don't know your specific setup, but the values of R1, R2 and the filter values will depend on: Make sure this is small enough to not be an issue for your application. Also, even with a 4pole filter, you may get a small amount of ripple on the output. So if you need to change the brightness quickly, you may want to use a real DAC. Note that this will be rather slow depending on your PWM frequency. Also since you are using 2n2222, I will assume relatively low LED current. If you are trying to turn on the LED as fast as the shutter, like a flash setup, this will not work. I will assume you just want to set the brightness and leave it on, then take the picture. You can use something like the following.

It can also be used in the various switching applications.ĢD dimensions will help you in placing this component at the time of making circuit on perf board or a PCB.You can indeed filter the PWM to control a current source.

Can be used to switch high current (upto 800mA) loads.

Note that the motor here draws about 500mA from the 12V power source, since the 2N2222 has collector current rating upto 800mA this circuit is possible had it been a BC547 the transistor should have been burnt. I have used a base voltage of 5V and a value of 1K as current limiting resistor. In actual circuit modifications might be required. To make things simple, I have shown a simplified circuit to make a transistor as switch. The value for this resistor can be calculated using the formula As the name suggests this resistor will limit the current flowing through the transistor to prevent it from damaging. However one important thing to notice is the Base resistor a.k.a current limiting resistor. This transistor will make it forward biased and thus closes the connection between collector and emitter.

The Base-Emitter voltage of this transistor is 6V so you just have to supply this voltage across the base and emitter of the transistor to induce a base current into the transistor. This transistor like all can be used either as a switch or as an amplifier. So if you looking for an NPN transistor that could switch loads of higher current, then 2N2222A might the right choice for your project. 2N2222A can allow collector current upto 800mA and also has power dissipation of 652mW which can be used to drive larger loads than compared with BC547. But there are two important features that distinguish both. The 2N2222A transistor is very much similar to the commonly used NPN transistor BC547. When base current is removed the transistor becomes fully off, this stage is called as the Cut-off Region and the Base Emitter voltage could be around 660 mV. This stage is called Saturation Region and the typical voltage allowed across the Collector-Emitter (V CE) or Base-Emitter (V BE) could be 200 and 900 mV respectively. When this transistor is fully biased, then it can allow a maximum of 800mA to flow across the collector and emitter. To bias a transistor we have to supply current to base pin, this current (I B) should be limited to 5mA. The maximum amount of current that could flow through the Collector pin is 800mA, hence we cannot connect loads that consume more than 800mA using this transistor. 2N2222A has a gain value of 110 to 800, this value determines the amplification capacity of the transistor. Note: Complete Technical Details can be found in the 2N2222A datasheet, given at the end of this page.īC549, BC636, BC639, BC547, 2N2369, 2N3055, 2N3904, 2N3906, 2SC5200 2N2222A Equivalent TransistorsĢN2907(PNP), 2N3904(PNP), 2N3906 (PNP), BC637, S9014, BC148, 2N4403, MPS2222, PN2222, KN2222, KTN2222ĢN2222A is a NPN transistor hence the collector and emitter will be left open (Reverse biased) when the base pin is held at ground and will be closed (Forward biased) when a signal is provided to base pin. Collector Emitter Voltage (V CE) is 30V.Continuous Collector current (I C) is 800mA.