TLE4729G_08 Datasheet, PDF (25/29 Pages) Infineon Technologies AG – 2-Phase Stepper-Motor Driver Bipolar-IC

TLE 4729 G
Application Hints (cont’d)
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 TLE4729G 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 outputs signal corresponding to the logic table the errors described below.
Logic Table
Kind of Error
Error 1
a) No error
H
b) Short circuit to GND
H
c) Open load¹⁾
L
d) b) and c) simultaneously
H
e) Temperature prealarm
L
1) _{Also possible: short circuit to + VS or short circuit of the load.}
Error Output
Error 2
H
L
H
L
L
Over-Temperature is implemented as pre-alarm; it appears approximately 20 K before
thermal shut down. To detect an open load, the recirculation of the inductive load is
watched. If there is no recirculation after a phase change-over, an internal error flipflop
is set. Because in most kinds of short circuits there won’t flow any current through the
motor, there will be no recirculation after a phase change-over, and the error flipflop for
open load will be set, too. Additionally an open load error is signaled after a phase
change-over during hold mode.
Data Sheet
25
V1.2, 2008-03-18