LV8731V
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13
Blanking Period
If, when exercising PWM constant−current chopping
control over the motor current, the mode is switched from
decay to charge, the recovery current of the parasitic diode
may flow to the current sensing resistance, causing noise to
be carried on the current sensing resistance pin, and this may
result in erroneous detection. To prevent this erroneous
detection, a blanking period is provided to prevent the noise
occurring during mode switching from being received.
During this period, the mode is not switched from charge to
decay even if noise is carried on the current sensing
resistance pin.
In the stepper motor driver mode (DM = Low or Open) of
this IC, the blanking time is fixed at approximately 1μs.
In the DC motor driver mode (DM = High), the blanking
time can be switched to one of two levels using the
RST/BLK pin. (Refer to “Blanking Time Switching
Function.”)
Reset Function
RST Operating Mode
Low Normal operation
High Reset state
Figure 7. Reset Function
RESET
RST
STEP
MONI
1ch output
2ch output
0%
Initial state
When the RST pin is set to High, the excitation position
of the output is forcibly set to the initial state, and the MONI
output is placed in the ON state. When RST is then set to
Low, the excitation position is advanced by the next STEP
input.
Output Enable Function
OE Operating Mode
Low Output ON
High Output OFF
Figure 8. Output Enable Function
OE
STEP
MONI
1ch output
2ch output
0%
Output is high−impedance
Power safe mode
When the OE pin is set High, the output is forced OFF and
goes to high impedance.
However, the internal logic circuits are operating, so the
excitation position proceeds when the STEP signal is input.
Therefore, when OE is returned to Low, the output level
conforms to the excitation position proceeded by the STEP
input.
