Rev0.7 May. 29, 2009(LF)

Technology

FS211F

APPLICATION NOTE

The Example of Typical Application Circuit

Figure 9 is the example of typical application circuit. The red, yellow, and black wires are the

input points of the motor system: red, the inputs of power supply; yellow, the output of FG; black,

the ground signal. Rc is an external pull-up resistance for the use of measuring FG signal. In

The formula is:

For example:

Vc = +5V for TTL level.

Ic = 5mA at 0.5V saturation voltage (IC specification.)

The safety value of Rc= 1KΩ

D1 is the reverse protection diode. As if the red and black wires reversely connect with the

power source, the current will flow through the ground via IC and coils L1 and L2 to power

supply. Under such kind of circumstances, the IC and coils are easy to be burned out.

Therefore, D1, the reverse protection diode, is necessary for the design. However, D1 will also

cause an extra voltage drop on the supply voltage.

C1 is a capacitor to reduce the ripple noise caused during the transient of the output stages.

The volume of the ripple noise depends on the coil impedance and characteristics.

L1

L2

D1

VC

RC

FG

OUTPUT

C1

B wire

Y wire

R wire

IC

FG

NO

SO

Internal circuit of 2-phase DC motor

VCC

FS211F

Fig.9 Application Circuit