TB6575FNG Datasheet, PDF (6/13 Pages) Toshiba Semiconductor – PWM Sensorless Controller for 3-Phase Full-Wave BLDC Motors

TB6575FNG
6. Fault protection
When a signal indicating the following faults is applied to the WAVE pin, the output transistors are
disabled. After about one second, the motor is restarted. This operation is repeated as long as a fault is
detected.
• The maximum commutation frequency is exceeded.
• The rotation speed falls below the forced commutation frequency.
V_SP (Pin5)
Output pin
ON
START (Pin8)
IP (Pin9)
SC (Pin9)
OFF
(a)
Fault detected
V_SP = 1 V or higher
When the SC pin capacitor = 0.47 µF
ON
and V_SP = 4 V
(a):
T_OFF
=
C_SC
×
(V_SP
i
−1)
= ^{0.47 µF × (4 − 1)}
1.5 µA
= 940 ms (typ.)
V_SP
1V
7. Motor position detection error
A position detection is synchronized with the PWM signal generated in the IC. Thus, a position detection
error relative to the PWM signal frequency may occur. Keep this in mind especially when the TB6575FNG
is used for a high-speed motor.
A detection is performed on the falling edge of the PWM signal. An error is recognized when the pin
voltage exceeds the reference voltage.
Detection error time < 1/fp
fp: PWM frequency = fXT/256
Output ON
fXT: Crystal oscillator frequency
Internal PWM signal
Pin voltage
Reference voltage
Pin voltage
Position sensing input
Ideal detection timing
6
Actual detection timing
2004/03/15