LV8712T

No.A1674-10/14

(10) Chopping frequency setting

For constant-current control, this IC performs chopping operations at the frequency determined by the capacitor

(Cchop) connected between the CHOP pin and GND.

The chopping frequency is set as shown below by the capacitor (Cchop) connected between the CHOP pin and GND.

Tchop ≒ C × V × 2 / I (s)

V : Width of suresshu voltage, typ 0.5V

I : Charge/discharge current, typ 10

μA

For instance, when Cchop is 200pF, the chopping frequency will be as follows :

Fchop ≒ 1 / Tchop (Hz)

(11) Output current vector locus (one step is normalized to 90 degrees)

Setting current ration in each excitation mode

2W1-2 phase (%)

W1-2 phase (%)

1-2 phase (%)

2-phase (%)

STEP

Channel 1

Channel 2

Channel 1

Channel 2

Channel 1

Channel 2

Channel 1

Channel 2

θ0

100

0

100

0

100

0

θ1

98

20

θ2

92

38

92

38

θ3

83

55

θ4

70

70

70

70

70

70

100

100

θ5

55

83

θ6

38

92

38

92

θ7

20

98

θ8

0

100

0

100

0

100

Channel 2 current ratio (%)

θ4' (2-phase)

0.0

33.3

66.7

100.0

0.0

33.3

66.7

100.0

θ 0

θ 1

θ 3

θ 5

θ 6

θ 7

θ 8

θ 2

θ 4