1. Field of the Invention
The present invention relates to a motor driving apparatus capable of operating in a normal mode or a sleep mode.
2. Description of the Related Art
In general, there has been increasing demand for electric or electronic devices in domestic, industrial and commercial settings in recent times.
In electric or electronic devices, a driving circuit for controlling a specific operation may be used, and as an example of a device using such a circuit, there is provided a motor.
A brushless direct current (BLDC) motor generally refers to a DC motor having a function of conducting current to a motor coil or adjusting a direction in which current flows in the motor coil, using a non-contact position detector and a semiconductor device, rather than a mechanical contact unit such as a brush, a commutator, or the like, in a DC motor.
In order to drive a BLCD motor, a driving apparatus may be used.
FIG. 1 is a schematic circuit diagram of a general motor driving apparatus.
Referring to FIG. 1, the general motor driving apparatus 10 may include a controlling unit 11 and a driving unit 12.
The controlling unit 11 may control driving of the motor, and the driving unit 12 may drive the motor by turning four field effect transistors (FETs) on or off in response to driving signals of the controlling unit 11 POUT1, POUT2, NOUT1, and NOUT2. In addition, as shown in FIG. 1, driving power VDD, required for motor driving, may be supplied.
FIG. 2 is a diagram showing driving signals of the motor driving apparatus shown in FIG. 1.
Referring to FIGS. 1 and 2, driving signals transferred from the controlling unit 11 to the driving unit 12 may be divided into four types and may be transferred in a sequence of identification numerals {circle around (1)}, {circle around (2)}, {circle around (3)}, and {circle around (4)}.
That is, a first PMOS FET P1 and a second NMOS FET N2 may be turned on in response to a driving signal represented by identification numeral {circle around (1)}, and the first PMOS FET P1 and the second NMOS FET N2 may be turned off and a second PMOS FET P2 and a first NMOS FET N1 may be turned on in response to a driving signal represented by identification numeral {circle around (2)}.
Again, the second PMOS FET P2 and the first NMOS FET N1 may be turned off and the first PMOS FET P1 and the second NMOS FET N2 may be turned on in response to a driving signal represented by identification numeral {circle around (3)}, and the first PMOS FET P1 and the second NMOS FET N2 may be turned off and the second PMOS FET P2 and the first NMOS FET N1 may be turned on in response to a driving signal represented by identification numeral {circle around (4)}.
In this driving scheme, when the first PMOS FET P1 and the second PMOS FET P2 are turned on, pulse width modulation (PWM) signals (oblique line portions of FIG. 2) are generated, whereby a speed of the motor may be controlled.
The motor driving apparatus as described above may have a function of operating normally in a normal mode and waiting for operation in a sleep mode in order to reduce consumption of current used in the invention disclosed in the Related Art Document.
As in the Related Art Document below, the normal mode and the sleep mode may be determined by the PWM signal.
FIG. 3 is a diagram showing operation conversion between the normal mode and the sleep mode.
Referring to FIG. 3, in the case in which the PWM signal is present for a preset time (for example, 1 ms), the motor driving apparatus may be operated in the normal mode N-M, and in the case in which the PWM signal is not present, the motor driving apparatus may be operated in the sleep mode S-M. Thereafter, in the case in which the PWM signal is present again, the motor driving apparatus may be returned to the normal mode.
Meanwhile, FIG. 4 is a diagram showing operation conversion between the normal mode and the sleep mode by noise.
As shown in FIG. 4, in the motor driving apparatus, conversion between the normal mode and the sleep mode may be frequently generated by unintended noise, which may increase power consumption of the motor driving apparatus.