Rainbow Electronics LM3813 - Manual (Page 12)

Look-Up Tables
The following tables show how to convert the duty cycle of
the PWM output to a current value, and vice versa. The
quantization error of 1 ⁄
2
bit is not shown in these tables.
Please see the “PWM Output and Current Accuracy” section
for more details.
TABLE 1. Current to Duty Cycle Conversion Table
Sense Current
(Amps)*
Duty Cycle
(%)
Sense Current
(Amps)*
Duty Cycle
(%)
1.00 95.5 -1.00 4.5
0.95 93.2 -0.95 6.8
0.90 90.9 -0.90 9.1
0.85 88.6 -0.85 11.4
0.80 86.4 -0.80 13.6
0.75 84.1 -0.75 15.9
0.70 81.8 -0.70 18.2
0.65 79.5 -0.65 20.5
0.60 77.3 -0.60 22.7
0.55 75.0 -0.55 25.0
0.50 72.7 -0.50 27.3
0.45 70.5 -0.45 29.5
0.40 68.2 -0.40 31.8
0.35 65.9 -0.35 34.1
0.30 63.6 -0.30 36.4
0.25 61.4 -0.25 38.6
0.20 59.1 -0.20 40.9
0.15 56.8 -0.15 43.2
0.10 54.5 -0.10 45.5
0.05 52.3 -0.05 47.7
0.00 50.0 -0.00 50.0
*Maximum Sense Current = 1.0 Amps for LM3812-1.0 and LM3813-1.0.
The sense current should be multiplied by 10 for LM3812-7.0 and LM3813-7.0.
LM3812/LM3813
www.national.com 12