Integrated Darlington pairs come packaged singly in transistor-like packages or as an array of devices (usually eight) in an integrated circuit.Ī third transistor can be added to a Darlington pair to give even higher current gain, making a Darlington triplet. Integrated devices can take less space than two individual transistors because they can use a shared collector. A typical integrated power device is the 2N6282, which includes a switch-off resistor and has a current gain of 2400 at I C=10 A. The maximum collector current I C(max) of the pair is that of Q 2. The Darlington pair has more phase shift at high frequencies than a single transistor and hence can more easily become unstable with negative feedback (i.e., systems that use this configuration can have poor performance due to the extra transistor delay).ĭarlington pairs are available as integrated packages or can be made from two discrete transistors Q 1, the left-hand transistor in the diagram, can be a low power type, but normally Q 2 (on the right) will need to be high power. This resistor provides a low-impedance discharge path for the charge accumulated on the base-emitter junction, allowing a faster transistor turn-off. To alleviate this, the second transistor often has a resistor of a few hundred ohms connected between its base and emitter terminals. The increased low output level can cause troubles when TTL logic circuits are driven.Īnother problem is a reduction in switching speed or response, because the first transistor cannot actively inhibit the base current of the second one, making the device slow to switch off. For equal collector currents, this drawback translates to an increase in the dissipated power for the Darlington transistor over a single transistor. Β D a r l i n g t o n = β 1 ⋅ β 2 + β 1 + β 2 always.) Thus the 'saturation' voltage of a Darlington transistor is one V BE (about 0.65 V in silicon) higher than a single transistor saturation voltage, which is typically 0.1 - 0.2 V in silicon. It typically creates a high current gain (approximately the product of the gains of the two transistors, due to the fact that their β values multiply together).Ī general relation between the compound current gain and the individual gains is given by: It does not store any personal data.A Darlington pair behaves like a single transistor, meaning it has one base, collector, and emitter. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. The cookie is used to store the user consent for the cookies in the category 'Performance'. This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category 'Other.

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