13

4575D–BCD–09/05

ATA6830

In addition to the actual step frequency there is a maximum step frequency up to which the

actual step frequency can rise. To secure a correct operation at low supply voltages the maxi-

mum value for the stepping frequency is smaller at low voltages. If the supply voltage falls below

the 9V threshold, travel operation will suspend. To restart operation, the supply voltage has to

rise above 10.5V. The relation of the maximum step frequency and the supply voltage during

operation is shown in Table 3-4.

If the chip temperature exceeds the overtemperature warning threshold, the step speed is

reduced to 300 Hz. If the chip temperature rises further the output driver is shut off.

3.9

Step Operation

The stepping motor is operated in halfstep-compensation mode. The current for both coils is

shown in Figure 3-10. The current levels are increased when the temperature is below 0°C to

secure operation. For final tests at the end of the application production line the currents are

reduced.

Figure 3-10. Compensated Halfstep Operation

Table 3-4.

Maximum Step Frequency

Maximum Step Frequency

at Rising Voltage

Maximum Step Frequency

< 9V

No operation

No operation

9V to 9.5V

No operation

300 Hz (3.33 ms)

9.5V to 10V

No operation

500 Hz (2.03 ms)

10V to 10.5V

No operation

680 Hz (1,47 ms)

10.5V to 11V

850 Hz (1.17 ms)

850 Hz (1.17 ms)

> 11V

1000 Hz (1 ms)

1000 Hz (1 ms)

> 20V

No operation

No operation

700mA

500mA

-500mA

-700mA

700mA

500mA

-500mA

-700mA

12345

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coil A

coil B

half steps

half steps