lb11692jh Sanyo Semiconductor Corporation, lb11692jh Datasheet - Page 9

• Manufacturer Part Number: lb11692jh
• Description: 24v Fan Motor Driver Ic
• Manufacturer: Sanyo Semiconductor Corporation

LB11692JH Overview
1. Output Drive Circuit
2. Power Supply Stabilization
3. VREG Pin
4. FC Pin
5. VD Pin
6. Hall Effect Sensor Input Signals
7. Current Limiter Circuit
The LB11692JH uses a direct PWM drive technique. Since the motor speed can be controlled by holding the supply
voltage constant and changing the output duty, the power supply design can be simplified compared to designs used
with techniques that vary the supply voltage (such as PAM drive). The low side output transistor is switched with a
pulse-width modulated signal and the drive output is adjusted by changing the duty. The LB11692JH includes built-
in output diodes for the regenerative currents that occur when the PWM signal is off and during phase switching.
Since the LB11692JH 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 V CC
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 (V CC , 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.
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.
The capacitor connected to the FC pin is required to correct the control loop's frequency characteristics.
(It should be about 0.1µF.)
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 V CC 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 V CC and VD pins when the LB11692JH is used with V CC = 24V.
Signals with amplitudes greater than 80mVp-p are required for the Hall effect sensor inputs. If possible, we
recommend providing signal amplitudes in excess of 100mVp-p to minimize the effects of noise. Add capacitors
across the Hall inputs (between the + and - sides of each input) if the output waveforms are disrupted by noise during
phase switching.
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.
LB11692JH
No.A0333-9/12