LB11693JH Datasheet, PDF (9/12 Pages) Sanyo Semicon Device – Monolithic Digital IC 24V Fan Motor Driver IC

LB11693JH
LB11693JH Overview
1. Output Drive Circuit
The LB11693JH reduces motor vibration and noise by switching the output current smoothly when switching phases.
Since the Hall input waveform is used for the change in (slope of) the output current during phase switching, if the
slope of the Hall input waveform is too steep, the change in the output current during phase switching will also be too
steep and the effectiveness of this technique at lowering vibration and noise effect will be reduced. Thus the slope of
the Hall input waveform requires attention during application design.
Low side output transistor PWM switching is used for motor speed control. The drive output is adjusted by changing
the duty. The diodes between the outputs and VM used for the regenerative current when the PWM signal is in the
off state are built in.
If the slope (amplitude) of the Hall input waveform is large, and if used with a high current, the parasitic diodes
between the outputs and ground will operate due to the low side kickback during phase switching. If problems such
as disruption of the waveforms occur, connect either rectifying diodes or Schottky diodes between the outputs and
ground.
2. Power Supply Stabilization
Since the LB11693JH uses a control method based on PWM switching, the power supply lines are susceptible to
disruption. Electrolytic capacitors with an adequate capacitance for stabilization must be connected between VCC
and ground. If diodes are inserted in the power supply lines to prevent destruction of the equipment if the power
supply is connected in reverse, the power supply lines will be particularly susceptible to disruption. In this case, even
larger capacitors must be used. The connected electrolytic capacitors must be located as close as possible to the IC
pins (VCC, VM, and GND2). If the electrolytic capacitors cannot be attached close to the pins due to problems with
the heat sink or other issues, ceramic capacitors of about 0.1µF must be attached close to the pins.
3. VREG Pin
At the same time as being the 5V regulator output, the VREG pin is also the power supply for the IC internal control
circuits. Therefore, a capacitor of at least 0.1µF must be connected between the VREG pin and ground to stabilize the
control circuit power supply. The ground side of the connected capacitor must be connected to the GND1 pin with as
short a line as possible.
4. FC Pin
The capacitor connected to the FC pin is required to correct the control loop's frequency characteristics.
(It should be about 0.1μF.)
5. VD Pin
The VD pin supplies the low side output transistor drive current (a maximum of about 0.1A).
The IC internal power consumption is suppressed by connecting a resistor between the VCC and VD pins and
dividing power consumption due to the low side output transistor drive current with that resistor. Although the IC
internal power consumption due to the drive current can be reduced by lowering the VD pin voltage, a voltage of at
least 4V must be assured at the VD pin. Use a resistor in the range from about 50Ω (0.5W) to about 100Ω (1W)
between the VCC and VD pins when the LB11693JH is used with VCC = 24V.
6. Hall Effect Sensor Input Signals
Signal inputs with an amplitude (differential) of at least 50mVp-p are required for the Hall inputs. If the output
waveforms are disrupted by noise, capacitors must be connected between the Hall input pins (the + and - sides).
7. Current Limiter Circuit
The current limiter circuit limits the peak value of the output current to a current determined by the equation I =
VRF/Rf (where VRF = 0.5V (typical), Rf = current detection resistor value). When the limiter operates, it suppresses
the current by PWM control of the low side output transistor at the PWM frequency determined by the external
capacitor connected to the PWM pin, in particular, by reducing the on duty.
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