Book Analog Interfacing to Embedded Microprocessors
possible without making sensing difficult. As already mentioned, Interna-
tional Rectifier makes a series of MOSFETs known as SENSEFETs with an
extra pin that mirrors a fraction of the transistor current. This can be used
for current sensing.
174 Analog Interfacing to Embedded Microprocessors
Figure 7.14
H-bridge current sensing.
There are a number of ICs that can control and drive stepper motors. The
L6201 from SGS-Thompson is a typical part. The L6201 can drive motors up
to 5A with supply voltages up to 48v. The L6201 includes internal flyback pro-
tection diodes and includes a thermal shutdown that turns the motors off if
the part overheats. The L6201 is available in DIP, SMT, and multiwatt pack-
ages (Figure 7.15).
The LM18200 from National is another motor driver IC. This part includes
a pin that provides a thermal warning when the device is about to overheat.
Unlike the L6201, the LMD18200 does not require a sense resistor in the
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