lv8732v ON Semiconductor, lv8732v Datasheet - Page 19

• Manufacturer Part Number: lv8732v
• Description: Bi-cmos Lsi Pwm Constant-current Control Stepping Motor Driver
• Manufacturer: ON Semiconductor

(4) Current limit reference voltage setting function
By setting a current limit, this IC automatically exercises short braking control to ensure that when the motor current
has reached this limit, the current will not exceed it.
(Current limit control time chart)
The limit current is set as calculated on the basis of the voltage input to the VREF pin and the resistance between the
RF pin and GND using the formula given below.
The voltage applied to the VREF pin can be switched to any of the four setting levels depending on the statuses of the
two inputs, ATT1 and ATT2.
Function for attenuating VREF input voltage
The formula used to calculate the output current when using the function for attenuating the VREF input voltage is
given below.
Example : At VREF of 1.5V, a reference voltage setting of 100% [(ATT1, ATT2) = (L, L)] and an RF resistance of
ATT1
High
High
Low
Low
0.3Ω, the output current is set as shown below.
If, in this state, (ATT1, ATT2) has been set to (H, H), Ilimit will be as follows :
Ilimit = (VREF/5) /RF resistance
Ilimit = (VREF/5) × (attenuation ratio) /RF resistance
Ilimit = 1.5V/5 × 100%/0.3Ω = 1.0A
Ilimit = 1.0A × 20% = 200mA
Coil current
fchop
Current mode
ATT2
High
High
Low
Low
Set current
Current setting reference voltage attenuation ratio
CHARGE
Forced CHARGE
section
Current mode
LV8732V
SLOW
100%
80%
50%
20%
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