122-28176 Parallax Inc, 122-28176 Datasheet - Page 149

• Manufacturer Part Number: 122-28176
• Description: GUIDE STUDENT PROCESS CONTROL
• Manufacturer: Parallax Inc

Specifications of 122-28176

• Accessory Type: Manual
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Propeller Education (PE) Kit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Rs-on is typically less than 1 ohm. Applying a low (0 V) to the gate places the device in
cutoff. In this state there is virtually no load current and the MOSFET acts as an open
switch.
The power MOSFET is very easy to drive with the BASIC Stamp. A metal oxide (MOS)
layer between the source and the gate acts as an excellent insulator. The extremely high
input impedance provided by this MOS layer means that no gate current is required to
control this device. Since no current is required to drive the gate, a single output from the
BASIC Stamp can control multiple MOSFETs. With proper heat sinks, the BS170 can
handle load currents up to 5 amps, or 500 mA continuous without heat sinks. These
features make the power MOSFET very easy to apply in industrial applications such as
driving relays, solenoids, and small DC motors.
It should be noted that these types of loads are inductive. When switching off the load,
this inductance can produce a reverse voltage transient that may be damaging to
MOSFETs and BJTs. A diode is often used to provide protection for the transistor when
driving inductive loads such as these. However, a diode is not necessary for the small
brushless motor used in our experiments.
BJTs and MOSFETs are compared in Table 5-1.
While the MOSFET makes an excellent electronic switch, it is not suited for small signal
amplification where linear control is required, such as in audio.
Power MOSFETs, like their CMOS cousins, are susceptible to damage from static
discharge and reverse voltage transients. Care should be taken when handling and
installing the device. Hold the device by its body, avoid touching its leads, and be sure that
the work surface and soldering equipment is properly grounded.
Switching Speed
Linear Response
Control Current
Characteristic
Table 5-1: Comparison of BJT and MOSFET Transistors
Load Current
Load Voltage
Higher
Lower
Lower
Lower
Good
BJT
Practically zero
MOSFET
Higher
Higher
Higher
Poor