lv8105w ETC-unknow, lv8105w Datasheet - Page 19

• Manufacturer Part Number: lv8105w
• Description: For Variable Speed Control Three-phase Brushless Motor Predriver
• Manufacturer: ETC-unknow

10. Forward/Reverse switching circuit
11. Constraint protection circuit
12. Clock disconnection protection circuit
13. Thermal shutdown circuit
The motor rotation direction can be switched by using the F/R pin. However, the following notes must be observed if
the motor direction is switched while the motor is turning.
• This IC is designed to avoid through currents when switching directions. However, increases in the motor supply
• If the motor current after direction switching exceeds the current limit value, the PWM drive side outputs will be
The LV8105W includes an on-chip constraint protection circuit to protect the motor and the output transistors in motor
constraint mode. If the LD output remains high (indicating the unlocked state) for a fixed period in the motor drive state
(the S/S pin : start, the BR pin : brake release), the lower side output transistors (the UL, VL and WL side) are turned off.
This time can be set by adjusting the oscillation frequency of the CSD pin by using a external capacitor. By the
capacitance of the capacitor attached to the CSD pin, the set time is calculated as follows.
When a 0.047µF capacitor is connected with the CSD pin, the set time becomes about 2.9sec.
By the variance of the IC, “60.8” of the above formula has varied from 40.8 to 80.8.
To restart a motor by cancelling the constraint protection function, any of the following operation is necessary.
• Put the S/S pin into the start state again after the stop state (about 1ms or more).
• Put the BR pin into the brake release state again after the braking state (about 1ms or more).
• Turn on the power supply again after the turn off state.
When the clock disconnect protection function, the thermal shutdown function and the low-voltage protection function
are operating, the constraint protection function does not operate even if the motor does not rotate.
The oscillation waveform of the CSD pin is used as the reference signal for some circuits in addition to the motor
constraint protection circuit. Therefore, it is desirable to oscillate the CSD pin even if the constraint protection function
is unnecessary. If the constraint protection circuit is not used, the oscillation of the CSD pin must be stopped by
connecting a 220kΩ resistor and a 0.01µF capacitor in parallel between the CSD pin and GND. However, in that case,
the clock disconnection protection circuit will no longer function. Also, the synchronous rectification does not operate
in any of the following cases.
• When the motor does not rotate in the motor constrained state since the motor is started up by the S/S or the BR input,
The CSD pin combines also functions as the initial reset pin. The time that the CSD pin voltage is charged to about
1.25V is determined as the initial reset. At the initial reset, all the outputs will be in the off state.
If the clock input through the CLK pin goes to the no input state in the motor drive state (the S/S pin : start, the BR pin :
brake release), the lower side output transistors (the UL, VL and WL side) are turned off. If the clock is resupplied, the
clock disconnection protection function is cancelled.
When the clock period is longer than about thirty-fourth part of the constraint protection set time, the clock
disconnection protection circuit judges the clock input to be the no input state and this protection function will operate.
If the junction temperature rises to the specified temperature (TSD) in the motor drive state (the S/S pin : start, the BR
pin : brake release), the lower side output transistors (the UL, VL and WL side) are turned off. If the junction
temperature falls to more than the hysteresis width (∆TSD), the thermal shutdown function is cancelled.
voltage (due to instantaneous return of the motor current to the power supply) during direction switching may cause
problems. The values of the capacitors inserted between power and ground must be increased if this increase is
excessive.
turned off, but the opposite side output will be in the short-circuit braking state, and a current determined by the motor
back EMF voltage and the coil resistance will flow. Applications must be designed so that this current does not exceed
the ratings of the output transistors used. (The higher the motor speed at which the direction is switched, the more
severe this problem becomes.)
the PWM switching is performed by using the current limiter circuit. But, the synchronous rectification does not
operate when the oscillation of the CSD pin is stopped.
The set time (sec) = 60.8 × C (µF)
LV8105W
No.A1271-19/21