lv8104v Sanyo Semiconductor Corporation, lv8104v Datasheet - Page 17

• Manufacturer Part Number: lv8104v
• Description: Three-phase Brushless Motor Predriver
• Manufacturer: Sanyo Semiconductor Corporation

8. Braking circuit
9. Forward/Reverse switching circuit
10. Constraint protection circuit
When the BR pin is set to the high level or open, the brake is on. Inversely, when the BR pin is set to the low level, the
brake is released. The brake becomes a short brake that turns on the upper side output transistors for all phases (the UH,
VH and WH side) and turns off the lower side output transistors for all phases (the UL, VL and WL side). Note that the
current limiter does not operate during braking. The current that flows in the output transistors during braking is
determined by the motor back EMF voltage and the coil resistance. 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 braking is applied, the
more severe this problem becomes).
The BR pin can be switching at the start mode. (This IC is designed to avoid through currents at changeover.) This
means that motor startup and stop control can be performed using the BR pin with the S/S pin held at the low level (the
start mode). If the startup time becomes excessive, it can be reduced by controlling the motor startup and stop with the
BR pin rather than with the S/S pin (Since the IC will be in the power save state at the stop mode, enough time for the
VCO circuit to stabilize will be required at the beginning of the motor start operation).
The motor rotation direction can be switched by using the F/R pin. However, the following notes must be observed if
the F/R pin is switched while the motor is rotating.
• This IC is designed to avoid through currents at changeover. However, the rise in the motor supply voltage (due to
• If the motor current after direction switching exceeds the current limit value, the PWM drive side outputs will be
This IC includes the constraint protection circuit to protect the motor and the output transistors in the motor constrained
state. 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 value (C) 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.
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 does not operate too. And, the synchronous rectification does not operate in
any of the following cases.
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.
instantaneous return of the motor current to the power supply) during direction switching may cause problems. If this
rise is a problem, the value of the capacitor inserted between power and ground must be increased.
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.)
• Put the S/S pin into the start state again after the stop mode (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 motor does not rotate in the motor constrained state since the motor is started up by the S/S or the BR
input, 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)
LV8104V
No.A1677-17/19