NCV70522MN(2012) 데이터 시트보기 (PDF) - ON Semiconductor

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NCV70522MN
(Rev.:2012)

Micro-Stepping Motor Driver

ON Semiconductor 

NCV70522MN

Automatic Duty Cycle Adaptation

In case the supply voltage is lower than 2*Bemf, then the

duty cycle of the PWM is adapted automatically to >50% to

Icoil

Duty Cycle

< 50%

Duty Cycle > 50%

maintain the requested average current in the coils. This

process is completely automatic and requires no additional

parameters for operation.

Duty Cycle < 50%

Actual value

Set value

t

TPWM

Figure 8. Automatic Duty Cycle Adaptation

Step Translator

Step Mode

The Step Translator provides the control of the motor by

means of SPI register Stepmode: SM[2:0], SPI register

DIRCNTRL and input pins DIR and NXT. It is translating

consecutive steps in corresponding currents in both motor

coils for a given stepmode.

One out of 7 possible stepping modes can be selected

through SPI−bits SM[2:0] (Table 12).

After power−on or hard reset, the coil−current translator

is set to the default 1/32 micro−stepping at position ‘0’.

Upon changing the Step Mode, the translator jumps to

position 0* of the corresponding stepping mode. When

remaining in the same Step Mode, subsequent translator

positions are all in the same column and increased or

decreased with 1. Table 10 lists the output current vs. the

translator position.

As shown in Figure 9 the output current−pairs can be

projected approximately on a circle in the (Ix,Iy) plane.

There are however two exceptions: uncompensated half step

and full step. In these stepmodes the currents are not

regulated to a fraction of Imax but are in all intermediate steps

regulated at 100%. In the (Ix,Iy) plane the current−pairs are

projected on a square. Table 9 lists the output current vs. the

translator position for these cases.

Table 9. SQUARE TRANSLATOR TABLE FOR FULL STEP AND UNCOMPENSATED HALF STEP

Stepmode ( SM[2:0] )

101

110

% of Imax

MSP[6:0]

Uncompensated Half−Step

Full Step

Coil x

000 0000

0*

−

0

001 0000

1

1

100

010 0000

2

−

100

011 0000

3

2

100

100 0000

4

−

0

101 0000

5

3

−100

110 0000

6

−

−100

111 0000

7

0

−100

Coil y

100

100

0

−100

−100

−100

0

100

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