BC547 AlternativesĪ complete modern equivalent of BC547 is BC550. The complementary pair with the PNP structure for it is BC557. This is due to the widespread use of such devices in the primary amplification stages in the pair. The Complementary PairĪ low-noise transistor designed to amplify weak high-frequency signals almost always has a complementary pair with a different conductivity type and a similar hFE gain. A higher hFE level simply assigns more sensitivity to a particular device, which means that it can start at the lowest base currents but still switch heavier loads through its collector. These values are essential for a bipolar and are one of the first criteria for its selection. For example, group “C”, according to the hFE U classification, starts at 420 and ends at 800. The BC547 has a fairly large current amplification factor (hFE). Usually, the tests are performed at an ambient temperature of 77 degrees Fahrenheit (25 degrees Celsius) or less. A separate column (test condition) indicates the values at which the manufacturer tested the device in these characteristics. The device manufacturer specifies them right after the description of the limit values. Now let’s look at the electrical parameters of the BC547. The following is a complete list of BC547 operating limits taken from Fairchild Semiconductor’s datasheet. The addition “max”, in the parameter limits, indicates the maximum values, but sometimes it is omitted from the description. This value is quite consistent with, and interrelated to, IC(max) and is 500 mW or half a watt for the entire group. PC (max) is the maximum power of the devices or the nominal load that can be connected through its collector-emitter.Therefore, it is recommended to use it at values less than half of IC (max). ![]() So you can see that it starts to heat up well even before reaching this limit, already at 60 mA. The BC547 should not be more than 100mA because this value will be the breakdown limit, above which the device will surely burn out.
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