an44066a Panasonic Corporation of North America, an44066a Datasheet - Page 24

• Manufacturer Part Number: an44066a
• Description: Driver Ic For Stepping Motor
• Manufacturer: Panasonic Corporation of North America

AN44066A
9. VREF voltage
10. Notes on the interface
8. Pulse blanking time
Usage Notes (continued)
When VREF voltage is set to lower, an error detection of motor current might be caused by noise because Comp threshold voltage
(No.31, 32, 33 in the “Electrical Characteristics” / P.10) becomes low. Use this IC after confirming there is no error detection
when VREF voltage is less than the set value.
Absolute maximum ratings of Pin 19, 20, 22 and Pin 24 to Pin31 are –0.3 V to 6 V. When the current setting for a motor is large
and the lead line of GND is long, the potential of GND in this LSI will rise. Take notice that there is a possibility that potential of
the interface pin is negative compared with that of GND in this LSI even if 0 V is applied to the interface pin. At that time, pay
attention so that the input voltage of these pins might not exceed the values which are set in the allowable voltage range.
In order to prevent mistakes in current detection resulting noise, this IC is provided with a pulse blanking time of 0.75 μs (typ.).
The motor current will not be less than the current determined by the pulse blanking time. Pay utmost attention at the time of
minute current control.
Fig.1 shows the relationship between the pulse blanking time and minimum current value.
The increase or decrease in the motor current is determined by a load and a resistance of a internal winding in the motor, induced
voltage, and PWM on-duty.
Normal operation
The set current is
less than the
minimum current.
Fig. 1
T
B
1/f
PWM
RCS current waveform
SDL00014AEB
Set current
Minimum current
Set current
f
T
PWM
B
: PWM frequency
: Pulse blanking time
(Refer to No. 28 to No. 30 of
Electrical Characteristics)
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