LV8210W Datasheet, PDF (12/15 Pages) Sanyo Semicon Device – A Spindle + CD-ROM Actuator

LV8210W
2. Soft Switching Circuit
This IC performs “soft switching”, which is a technique that varies the duty and achieves quieter motor operation by
reducing the level of motor drive noise. This IC provides a “current application on/off dual sided soft switching” type
soft switching function.
3. Current Limiter Circuit
The current limit value of the current limiter circuit is determined by RF in the equation I = VRF/Rf (here, VRF =
0.20V, typical).
The current limiter circuit detects the RF1 pin (pin 1) peak current at the RF2 pin (pin 2) and turns the sink side
transistor off.
4. VCO Circuit Constants
The LV8210W spindle block adopts a sensorless drive technique. Sensorless drive is implemented by detecting the
back EMF signal generated by the motor and setting the commutation timing accordingly. Thus the timing control
uses the VCO signal. We recommend using the following procedure to determine the values of the VCO circuit’s
external components.
1) Connect components with provisional values.
Connect a 2.2μF capacitor between the VCOIN pin (pin 16) and ground, connect a 68kΩ resistor between the
RMAX pin (pin 14) and ground, and connect a 2200pF capacitor between the VCO pin (pin 15) and ground.
2) Determine the value of the VCO pin (pin 13) capacitor.
Select a value such that the startup time to the target speed is the shortest and such that the variations in startup
time are minimized. If the value of this capacitor is too large, the variations in the startup time will be excessive,
and if too small, the motor may fail to turn. Since the optimal value of the VCO pin constant differs with the motor
characteristics and the startup current, the value of this component must be verified again if the motor used or any
circuit specifications are changed.
3) Determine the value of the RMAX pin (pin 14) resistor.
Select a resistor value such that the VCOIN pin voltage is about VCC – 1.1V or lower with the motor operating at
the target maximum speed. If the value of this resistor is too large, the VCOIN pin voltage may rise excessively.
4) Determine the value of the VCOIN pin (pin 16) capacitor.
If the FG output (pin 9 and 10) pulse signal becomes unstable at the lowest motor speed that will be used, increase
the value of the VCOIN pin capacitor.
5. S/S and MUTE Circuit
The S/S pin (pin 30) functions as the spindle motor driver’s and the actuators motor driver’s start/stop pin ; a
high-level input specifies that the operation is in the start state. The MUTE pin (pin 32) operates on all driver blocks
other than the spindle block; a low-level input mutes these outputs. In the muted state, the corresponding drivers (H
bridge) all go to the high-impedance state, regardless of the states of the logic inputs.
A low level input must be applied to the S/S pin to set the IC to the standby state (power saving mode).
When power is supplied to VCC, set either S/S pin or MUTE pin (or both) to low-level.
6. BRK Circuit
The BRK pin (pin 31) switches between reverse torque and short-circuit braking; a high level selects short-circuit
braking and a low level selects reverse torque breaking. When the motor speed becomes adequately slow in the reverse
torque braking state, the application must switch to the short-circuit braking state to stop the motor. (Note: The IC
must not be in the power saving state at this point.)
When stopping the motor in the state where the control voltage, VCTL, is less than VCREF (when a low level is input
to the BRK pin), if the timing of the switch to short-circuit braking is too early, and remaining motor rotation is a
problem, reduce the value of the RMAX pin (pin 14) resistor. Also, if motor oscillation continues when the motor is
nearly stopped, and a switch to short braking mode does not occur, insert a resistor with a value of a few kΩ at the
COM pin. (Note: Verify that inserting this resistor does not adversely affect the startup characteristics.)
7. FG Output Circuit
The FG3 pin (pin 10) is the spindle block FG output pin. It provides a pulse signal equivalent to that provided by
systems that use three Hall-effect sensors. The FG1 pin (pin 9) outputs a signal that follows the spindle output U phase
back EMF voltage. The FG1 and the FG3 pins both have a MOS open-drain output circuit structure.
This means that external pull-up resistors must be provided. Connect the power supply from the FG signal input side
as the pull-up resistor power supply. We recommended using a resistor of about 10kΩ.
No.7461-12/15