LV8804V Sanyo Semiconductor Corporation, LV8804V Datasheet - Page 9

• Manufacturer Part Number: LV8804V
• Description: PC and Server Fan Motor Driver
• Manufacturer: Sanyo Semiconductor Corporation

*5. RF pins
*6. SOFTST pin
*7. OSC pin
*8. MINSP pin
*9. VG, CP, and CPC pins
*10. VREG pins
These pins are used to set the current limit.
When the pin voltage exceeds 0.25V, the current is limited, and regeneration mode is established. In the application
circuit, this voltage is set in such a way that the current limit will be established at 1A.
The calculation formula is given below.
RF resistance = 0.25V/target current limit value
All the RF pins (pins 24, 26 and 27) must be short-circuited on the print pattern.
This pin is used to set the soft start.
By connecting a capacitor between this pin and GND, the motor speed can be increased gradually.
When the pin voltage exceeds 2.5V, the soft start is released, and the LV8804V is switched to normal control.
If the soft start function is not going to be used, connect the pin to the VREG pin.
This pin is used to connect the capacitor for setting the startup frequency.
A capacitor with a capacitance ranging from about 500pF to 2,200pF (reference value) must be connected between
this pin and GND.
The OSC pin determines the motor startup frequency, so be sure to connect a capacitor to it.
<How to select the capacitance>
Select a capacitance value that will result in the shortest possible startup time for achieving the target speed and
produce minimal variations in the startup time. If the capacitance is too high, variations in the startup time will
increase; conversely, if it is too low, the motor may idle. The optimum OSC constant depends on the motor
characteristics and startup current, so be sure to recheck them when the type of motor used or circuit specifications are
changed.
This pin is used to input the voltage to set the minimum speed.
The minimum speed can be set by resistor-dividing the VREG voltage (5V) to create a voltage of 1 to 3V, and
inputting this voltage to the MINSP pin.
If the minimum speed is not going to be set, the MINSP pin and CTL pin (pin 8) must be short-circuited.
These pins are used to connect the capacitors to generate the pre-drive voltage and stabilize the pre-drive power
supply.
Be sure to connect these capacitors in order to generate the drive voltage for the high-side (upper) output DMOS
transistor.
These are the control system power supply pin and regulator output pin, which create the power supply of the control
unit. Be sure to connect a capacitor between this pin and GND in order to stabilize control system operation.
Since these pins are used to supply current for control and generate the charge pump voltage, connect a capacitor with
a capacitance that is higher than that of the capacitor connected to the charge pump.
Both the VREG pins (pins 3 and 4) must be short-circuited on the print pattern.
LV8804V
No.A1407-9/10