LB11822 Datasheet, PDF (10/11 Pages) Sanyo Semicon Device – Three-Phase Brushless Motor Driver for OA Products

LB11822
4. Power save circuit
This IC enters the power save condition to decrease the current dissipation in the stop mode. In this condition, the bias
current of most of circuits is cut off. Even in the power save condition, the 5 V regulator output is given.
5. Reference clock
This is entered from the external signal source (1 MHz max) via a resistor (reference: about 5.1 kΩ) in series with the
XI pin. The XO pin is left open.
Input signal source levels:
Low-level voltage: 0 to 0.8 V
High-level voltage: 2.5 to 5.0 V
6. Speed lock range
The speed lock range is ±6.25% of the constant speed. If the motor speed falls inside the lock range, the LD pin goes
to “L” (open collector output). When the motor speed falls outside the lock range, the on-duty ratio of motor drive
output changes according to the speed error, causing control to keep the motor speed within the lock range.
7. PWM frequency
PWM frequency is determined from the capacity C (F) of capacitor connected to the PWM pin.
f_PWM ≈ 1/(14,400 × C)
It is recommended to keep the PWM frequency at 15 kHz to 25 kHz
8. Hall input signal
The Hall input requires the signal input with an amplitude exceeding the hysteresis width (42 mV max). Considering
the effect of noise, the input with the amplitude of 100 mV or more is recommended.
9. F/R changeover
Motor rotation direction can be changed over with the F/R pin. When changing F/R while the motor is running, pay
attention to following points.
• For the through current at a time of changeover, the countermeasure is taken using a circuit. However, it is
necessary to prevent exceeding of the rated voltage (30 V) due to rise of V_CC voltage at a time of changeover
(because the motor current returns instantaneously to the power supply). When this problem exists, increase the
capacity of a capacitor between V_CC and GND.
• When the motor current exceeds the current limit value after changeover, the lower-side Tr is turned OFF. But, the
upper-side Tr enters the short-brake condition and the current determined from the motor counter electromotive
voltage and coil resistance flows. It is necessary to prevent this current from exceeding the rated current (3.1 A).
(F/R changeover at high speed is dangerous.)
10. Motor lock protection circuit
A motor lock protection circuit is incorporated for protection of IC and motor when the motor is locked.
When the LD output is “H” (unlocked) for a certain period in the start condition, the lower-side Tr is turned OFF. This
time is set with the capacity of the capacitor connected to the CSD pin. The time can be set to about 3.3 seconds with
the capacity of 10 µF (variance about ±30%).
Set time (s) ≈ 0.33 × C (µF)
When the capacitor used has a leak current, due consideration is necessary because it may cause error in the set time,
etc.
Cancelling requires either the stop condition or re-application of power supply (in the stop condition). When the lock
protection circuit is not to be used, connect the CSD pin to GND.
When the stop period during which lock protection is to be cancelled is short, the charge of capacitor cannot be
discharged completely and the lock protection activation time at restart becomes shorter than the set value. It is
necessary to provide the stop time with an allowance while referring to the following equation. (The same applies to
restart in the motor start transient condition.)
No. 7105-10/11