When using a BJT as a switch, power consumption is the product of Ic and Vce(sat)?
I'm looking at using a TIP127 to power a 26w resistive load @12v.
26w/12v = 2.17A
TIP127 Max Ic = 5A, so it "should" be able to switch this. But when I start figuring if it can handle the power, i'm not sure this is right.
TIP127 Pmax = 2W
Vce(sat) = 2v (max) @ 12ma Ib, Ic=3A
Vce(sat) x Ic = 2v X 2.17 A = 4.34W
Is this just a bad choice of transistor? or am I calculating the power dissipation wrong?
Should I just use a Logic Level Mosfet instead?
The load is a small heater, the transistor is to be driven by a MCU, and if necessary I can use another small transistor to drive the base, but the TIP127 should be driveable straight from MCU pin.
I'm looking at using a TIP127 to power a 26w resistive load @12v.
26w/12v = 2.17A
TIP127 Max Ic = 5A, so it "should" be able to switch this. But when I start figuring if it can handle the power, i'm not sure this is right.
TIP127 Pmax = 2W
Vce(sat) = 2v (max) @ 12ma Ib, Ic=3A
Vce(sat) x Ic = 2v X 2.17 A = 4.34W
Is this just a bad choice of transistor? or am I calculating the power dissipation wrong?
Should I just use a Logic Level Mosfet instead?
The load is a small heater, the transistor is to be driven by a MCU, and if necessary I can use another small transistor to drive the base, but the TIP127 should be driveable straight from MCU pin.