Motor Selection

Some stepper motor have such high core losses

that they are not suitable for switch mode current

regulation. Furthermore, some stepper motors are

not designed for continuous operating at maximum

current. Since the circuit can drive a constant cur-

rent through the motor, its temperature might ex-

ceed, both at low and high speed operation.

Unused Inputs

Unused inputs should be connected to the proper

voltage levels in order to get the highest noise im-

munity.

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 accord-

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%

OPERATION MODE TIME DIAGRAMS

Figure 5: Full step operation mode timing diagram (Phase - DAC input and Motor Current)

I3

I2

I1

I0

Current level

00

00

100

00

01

98.4

00

10

95.2

00

11

92.1

01

00

88.9

01

01

82.5

01

10

77.8

01

11

71.4

10

00

63.5

10

01

55.6

10

10

47.6

10

11

38.1

11

00

28.6

11

01

19.1

11

10

9.5

1

1

1

1

No Current

L6258

14/18