TLE4727 Datasheet, PDF (21/22 Pages) Siemens Semiconductor Group – 2-Phase Stepper-Motor Driver

TLE 4727
Optimizing Noise Immunity
Unused inputs should always be wired to proper voltage levels in order to obtain highest
possible noise immunity.
To prevent crossconduction of the output stages the TLE 4727 uses a special break
before make timing of the power transistors. This timing circuit can be triggered by short
glitches (some hundred nanoseconds) at the Phase inputs causing the output stage to
become high resistive during some microseconds. This will lead to a fast current decay
during that time. To achieve maximum current accuracy such glitches at the Phase
inputs should be avoided by proper control signals.
To lower EMI a ceramic capacitor of max. 3 nF is advisable from each output to GND.
Thermal Shut Down
To protect the circuit against thermal destruction, thermal shut down has been
implemented.
Error Monitoring
The error output signals with low-potential one of the following errors:
overtemperature implemented as pre-alarm; appears approximately 20 K before
thermal shut down.
short circuit
a connection of one output to GND for longer than 30 µs sets an
internal error flipflop. A phase change-over of the affected bridge
resets the flipflop. Being a separate flipflop for each bridge, the
error can be located in such way.
underload
the recirculation of the inductive load is watched. If there is no
recirculation after a phase change-over, the internal error flipflop is
set. Additionally an error is signaled after a phase change-over
during hold-mode.
Semiconductor Group
21
1998-12-16