Hello
I need to drive a little haptic vibrating motor from the output of a MCU. I'm running the circuit off 3V (a CR2032 coin cell). The motor works OK when directly connected to the battery and draws about 35mA. But I can't get enough current to it through a transistor. I first of all tried driving it through a MOSFET (a 2N7000) but it barely turns over, if at all. I tried it with a NPN transistor (2n3904) but again the motor only just works. Thinking it might be a problem of insufficient gain, I tried a Darlington, but again with no luck.
I guess that in the case of the MOSFET, the gate voltage from the MCU is just not quite enough to switch it on, or possibly at this gate voltage, the drain-source resistance is too high. If so, can anyone recommend something better (preferably small, cheap, easily available and in SMT). In the case of the NPN, my guess is that the voltage drop across the transistor is too much to power the motor, and the drop would be even greater with the Darlington.
I don't know much about all this or whether my guesses might be right, so would appreciate advice.
I need to drive a little haptic vibrating motor from the output of a MCU. I'm running the circuit off 3V (a CR2032 coin cell). The motor works OK when directly connected to the battery and draws about 35mA. But I can't get enough current to it through a transistor. I first of all tried driving it through a MOSFET (a 2N7000) but it barely turns over, if at all. I tried it with a NPN transistor (2n3904) but again the motor only just works. Thinking it might be a problem of insufficient gain, I tried a Darlington, but again with no luck.
I guess that in the case of the MOSFET, the gate voltage from the MCU is just not quite enough to switch it on, or possibly at this gate voltage, the drain-source resistance is too high. If so, can anyone recommend something better (preferably small, cheap, easily available and in SMT). In the case of the NPN, my guess is that the voltage drop across the transistor is too much to power the motor, and the drop would be even greater with the Darlington.
I don't know much about all this or whether my guesses might be right, so would appreciate advice.