17/22

L6258EP

5.2 Motor Selection

Some stepper motor have such high core losses that they are not suitable for switch mode current regulation. Fur-

thermore, some stepper motors are not designed for continuous operating at maximum current. Since the circuit

can drive a constant current through the motor, its temperature might exceed, both at low and high speed operation.

5.3 Unused Inputs

Unused inputs should be connected to the proper voltage levels in order to get the highest noise immunity.

5.4 Notes on PCB Design

We recommend to observe the following layout rules to avoid application problems with ground and anomalous

recirculation current.

The by-pass capacitors for the power and logic supply must be kept as near as possible to the IC.

It's important to separate on the PCB board the logic and power grounds and the internal charge pump circuit

ground avoiding that ground traces of the logic signals cross the ground traces of the power signals.

Because the IC uses the board as a heat sink, the dissipating copper area must be sized in accordance with the

6

OPERATION MODE TIME DIAGRAMS

Figure 12. Full step operation mode timing diagram (Phase - DAC input and Motor Current)

Ph2

FULL Step Vector

0

23

1

0

3

2

1

0

Position

DAC 2

Inputs

0

Motor drive

Current 2

0

Motor drive

Current 1

I3_2

I2_2

I1_2

I3_1

0

0

5V

0

5V

0

5V

0

5V

0

5V

0

5V

0

5V

0

5V

0

5V

DAC 1

Inputs

Phase

2

Phase

1

I0_2

I2_1

I1_1

I0_1

0

3

2

1

Ph1

Ph2

Ph1

D97IN629A

95.2%

19.1%

95.2%

19.1%

I3

I2

I1

I0

Current level

0000

100

0001

98.4

0010

95.2

0011

92.1

0100

88.9

0101

82.5

0110

77.8

0111

71.4

1000

63.5

1001

55.6

1010

47.6

1011

38.1

1100

28.6

1101

19.1

1110

9.5

1111

No Current