GS-D200 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
GS-D200 Datasheet PDF : 17 Pages
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GS-D200/GS-D200S
Figure 10: Two-Phase-on (Normal Mode) Drive Figure 11: One-Phase-on (Wave Mode) Drive
RESET, ENABLE AND HOME SIGNALS
The RESET is an asynchronous reset input which
restores the module to the home position (state 1 :
ABCD = 0101). Reset is active when low.
The HOME output signals this condition and it is
intended to be ANDed with the output of a mechani-
cal home position sensor.
The ENABLE input is used to start up the module
after the system initialization. ENABLE is active
when high or unconnected.
MOTOR CURRENT REGULATION
The two bipolar winding currents are controlled by
two internal choppers in a PWM mode to obtain
good speed and torque characteristics.
An internal oscillator supplies pulses at the chopper
frequency to both choppers.
When the outputs are enabled, the current through
the windings raises until a peak value set by Ioset
and Rsense (see the equivalent block diagram) is
reached. At this moment the outputs are disabled
and the current decays until the next oscillator pulse
arrives.
The decay time of the current can be selected by
the CONTROL input (pin 10). If the CONTROL input
is kept high or open the decay is slow, as shown in
fig. 12, where the equivalent power stage of GS-
D200, the voltages on A and B are shown as well
as the current waveform on winding AB.
When the CONTROL input is forced low, the decay
is fast as shown in fig. 13.
The CONTROL input is provided on GS-D200 and
GS-D200S to allow maximum flexibility in applica-
tion.
If the modules must drive a large motor that does
not store much energy in the windings, the chopper
frequency must be decreased: this is easily ob-
tained by connecting an external capacitor between
OSC pin and GND1.
In these conditions a fast decay (CONTROL LOW)
would impose a low average current and the torque
could be inadequate. By selecting CONTROL
HIGH, the average current is increased thanks to
the slow decay.
When the GS-D200S is used in the fast-decay
mode it is recommended to connect external fast
recovery, low drop diodes between each phase
output and the supply return (GND). The slow-de-
cay should be the preferred operating recirculation
mode because of the lower power dissipation and
low noise operations.
9/17
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