TABLE 2. Duty Cycle to Current Conversion Table

Duty Cycle

(%)

Sense Current

(Amps)

Duty Cycle

(%)

Sense Current

(Amps)

95.5

0.990

50.0

-0.000

92.5

0.935

47.5

-0.055

90.0

0.880

45.0

-0.110

87.5

0.825

42.5

-0.165

85.0

0.770

40.0

-0.220

82.5

0.715

37.5

-0.275

80.0

0.660

35.0

-0.330

77.5

0.605

32.5

-0.385

75.0

0.550

30.0

-0.440

72.5

0.495

27.5

-0.495

70.0

0.440

25.0

-0.550

67.5

0.385

22.5

-0.605

65.0

0.330

20.0

-0.660

62.5

0.275

17.5

-0.715

60.0

0.220

15.0

-0.770

57.5

0.165

12.5

-0.825

55.0

0.110

10.0

-0.880

52.5

0.055

7.5

-0.935

50.0

0.000

5.0

-0.990

The sense current should be multiplied by 10 for LM3812-7.0 and LM3813-7.0.

Timing Diagram

DS100122-11

Duty cycle of the PWM waveform during any sampling interval indicates the current magnitude (average) and direction during the previous sampling interval.

FIGURE 9. Typical Timing Diagram for Mostly Positive Current

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