SPINDLE MOTOR DRIVER

M56784FP

MITSUBISHI <CONTROL / DRIVER IC>

HALL AMPLIFIER INPUT AND COMMUTATION

The relationship between the hall amplifier inputs voltage and the motor current outputs is shown in Figure 2.

Hu+

Hv+

Hw+

SINK

SOURSE

Output

current

Hall

inputs

U

V

W

V

U

V

W

W

U

Figure 2.

HALL AMPLIFIER INPUT SENSITIVITY SELECT

Figure 3 shows the hall amplifier input sensitivity select function.

You are able to select a sensitivity of a hall amplifier out of two

levels which is suitable for the hall elements type.

If the output minimum level of the hall elements is lower than

50mVp-p, please connect the MODE4 pin to external GND. In this

case, the output current changes shaply. If the output minimum

level of the hall elements is higher than 50mVp-p, please make the

MODE4 pin open, then the output current is commutated softly.

We recommend that the output level of the hall elements be set

between 80mVp-p and 120mVp-p, and the MODE4 pin is an open.

Figure 3.

MODE4

OPEN or HIGH

GND

120 degree

soft switching

120 degree switching

** Io current

changes sharply.

The hall amp

minimum input

voltage is

50mVp-p.

The hall amp

minimum input

voltage is

35mVp-p.

W

Hall elements

Outer loator

FORWARD

EC < ECR

U

W

V

U

W

W

V

U

V

U

V

REVERSE

EC > ECR

SLEEP MODE FUNCTION

Figure 4.

Figure 4 shows the sleep mode function. If the

pin [S/S] is set to

be open or low, the motor drive outputs have high impedance and

the motor stops. Then, the IC bias current will be a slight current

(please refer to the electrical characteristics), and the hall bias

output will be cut off. When the

pin input is high, all the circuits

will work.

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41

START / STOP (

pin)

LOW or OPEN

HIGH

Motor Stop

Bias off

Hall-Bias off

Motor on

Bias on

Hall-Bias on

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