MC3479

http://onsemi.com

7

Figure 7. Output Sequence

Phase A

Output

(a) Full Step Mode

A

CW/CCW

A

A

A

A

Bias/Set

Clk

Phase A

Output

Phase A

A

(c) Half Step Mode

CD

L3

L4

F

L1

E

C

L1

L2

L2

L3

L4

BD

L1

CD

B

H

G

D

BC

E

F

(b) Half Step Mode

L2

L3

L4

GH

B

B

C

D

B

C

B

= Logic 0"

= Logic 1"

= Logic 1"

= High Impedance

CW/CCW

= Logic 0"

F/HS

= Logic 1", OIC = Logic 0"

D

BC

= High Impedance

= Logic 0"

= Don

′t Care

F/HS

OIC

CW/CCW

F/HS

OIC

determined by:

R

B +

V

M *

0.7 V

I

BS

< 5.0

mA, the internal logic is set to the Phase A condition, and

the four driver outputs are put into a high impedance state.

The Phase A output (Pin 11) goes active (low), and input

signals at the controls are ignored during this time. Upon

controls.

The Set function (opening this pin) can be used as a

powerup reset while supply voltages are settling. A CMOS

shown in Figure 12.

c) Whenever the motor is not being stepped, power

dissipation in the IC and in the motor may be lowered by

not reset the internal logic as described above. See Figure 13

for a suggested circuit.

Power Dissipation

The power dissipated by the MC3479 must be such that

power dissipated can be expressed as:

where

After the power dissipation is calculated, the junction

temperature can be calculated using:

where

(52

°C/W for the DIP, 72°C/W for the FN Package);