Datasheet

Power_LSB=20Current_LSB
Power_LSB=400 10´
-6
Max_Current=Current_LSB 32767´
Max_Current=0.65534
Max_ShuntVoltage=Max_Current_Before_Overflow R´
SHUNT
Max_ShuntVoltage=0.32
MaximumPower=Max_Current_Before_Overflow V´
BUS_MAX
MaximumPower=20.48
Corrected_Full_Scale_Cal=trunc
Cal MeasShuntCurrent
TMP513_Current
´
Corrected_Full_Scale_Cal=3548
TMP512
TMP513
www.ti.com SBOS491A –JUNE 2010– REVISED MAY 2011
6. Calculate the Power LSB with Equation 10. Equation 10 shows a general formula; because the bus voltage
measurement LSB is always 4mV, the power formula reduces to the calculated result.
(10)
7. Compute the maximum current and shunt voltage values (before overflow), as shown by Equation 11 and
Equation 12. Note that both Equation 11 and Equation 12 involve an If - then condition:
(11)
If Max_Current ≥ MaxPossible_I then
Max_Current_Before_Overflow = MaxPossible_I
Else
Max_Current_Before_Overflow = Max_Current
End If
(Note that Max_Current is greater than MaxPossible_I in this example.)
Max_Current_Before_Overflow = 0.64
(12)
If Max_ShuntVoltage ≥ V
SHUNT_MAX
Max_ShuntVoltage_Before_Overflow = V
SHUNT_MAX
Else
Max_ShuntVoltage_Before_Overflow= Max_ShuntVoltage
End If
(Note that Max_ShuntVoltage is greater than V
SHUNT_MAX
in this example.)
Max_ShuntVoltage_Before_Overflow = 0.32
8. Compute the maximum power with Equation 13.
(13)
9. (Optional second Calibration step.) Compute corrected full-scale calibration value based on measured
current.
TMP513_Current = 0.63484
MeaShuntCurrent = 0.55
(14)
Figure 32 illustrates how to perform the same procedure discussed in this example using the automated
TMP512/13EVM software. Note that the same numbers used in this nine-step example are used in the software
example. Note also that Figure 32 illustrates which results correspond to which step (for example, the information
entered in Step 1 is enclosed in a box in Figure 32 and labeled).
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