MC3479 데이터 시트보기 (PDF) - ON Semiconductor

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MC3479

Stepper Motor Driver

ON Semiconductor 

MC3479

3.0 V

Clk

0

PWCLKH

1.5 V

tPCD

L1 - L4

Outputs

6.0 V

3.0 V

F/HS,

CW/CCW

Inputs 0

Phase A

Output

PWCLKL

tsu th

1.5 V

tPHLA

1.5 V

tPLHA

Figure 4. Clock Timing

(Refer to Figure 2)

Note: tr, tf (10% to 90%) for

input signals are p 10 ns.

VM

VD

B/S

RB

IBS

I′BS

Current

Drivers

and

Logic

QH

QH

Motor Coil

L1

QL

L2

QL

Parasitic

Diodes

To L3, L4

Transistors

Logic Decoding

Circuit

CW / CCW

OIC

F/HS

Clk

Inputs

Figure 5. Output Stages

The maximum sink current available at the outputs is a

function of the resistor connected between Pin 6 and ground

(see section on Bias/Set operation). Whenever the outputs

are to be in a high impedance state, both transistors (QH and

QL of Figure 5) of each output are off.

VD

This pin allows for provision of a current path for the

motor coil current during switching, in order to suppress

back–EMF voltage spikes. VD is normally connected to VM

(Pin 16) through a diode (zener or regular), a resistor, or

directly. The peaks instantaneous voltage at the outputs must

not exceed VM by more than 6.0 V. The voltage drop across

the internal clamping diodes must be included in this portion

of the design (see Figure 6). Note the parasitic diodes

(Figure 5) across each QL of each output provide for a

complete circuit path for the switched current.

3.0

2.0

1.0

0

0

100

200

300

ID (mA)

Figure 6. Clamp Diode Characteristics

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